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openssh-portable
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- OpenBSD CVS updates: 

- [atomicio.c auth-krb4.c bufaux.c channels.c compress.c fingerprint.c]
     [packet.h radix.c rsa.c scp.c ssh-agent.c ssh-keygen.c sshconnect.c]
     [sshd.c]
     pedantic: signed vs. unsigned, void*-arithm, etc
   - [ssh.1 sshd.8]
     Various cleanups and standardizations.
This commit is contained in:
Damien Miller 2000-03-17 23:40:15 +11:00
parent d6121d2972
commit 7684ee17ee
17 changed files with 377 additions and 260 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
ChangeLog
View File

@ -5,6 +5,13 @@
<jmknoble@pobox.com> <jmknoble@pobox.com>
- Checks for 64 bit int types. Problem report from Mats Fredholm - Checks for 64 bit int types. Problem report from Mats Fredholm
<matsf@init.se> <matsf@init.se>
- OpenBSD CVS updates:
- [atomicio.c auth-krb4.c bufaux.c channels.c compress.c fingerprint.c]
[packet.h radix.c rsa.c scp.c ssh-agent.c ssh-keygen.c sshconnect.c]
[sshd.c]
pedantic: signed vs. unsigned, void*-arithm, etc
- [ssh.1 sshd.8]
Various cleanups and standardizations.
20000316 20000316
- Fixed configure not passing LDFLAGS to Solaris. Report from David G. - Fixed configure not passing LDFLAGS to Solaris. Report from David G.

7
atomicio.c
View File

@ -24,7 +24,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: atomicio.c,v 1.9 2000/03/09 10:27:50 damien Exp $"); RCSID("$Id: atomicio.c,v 1.10 2000/03/17 12:40:15 damien Exp $");
#include "xmalloc.h" #include "xmalloc.h"
#include "ssh.h" #include "ssh.h"
@ -33,12 +33,13 @@ RCSID("$Id: atomicio.c,v 1.9 2000/03/09 10:27:50 damien Exp $");
* ensure all of data on socket comes through. f==read || f==write * ensure all of data on socket comes through. f==read || f==write
*/ */
ssize_t ssize_t
atomicio(f, fd, s, n) atomicio(f, fd, _s, n)
ssize_t (*f) (); ssize_t (*f) ();
int fd; int fd;
void *s; void *_s;
size_t n; size_t n;
{ {
char *s = _s;
ssize_t res, pos = 0; ssize_t res, pos = 0;
while (n > pos) { while (n > pos) {

9
auth-krb4.c
View File

@ -186,19 +186,20 @@ auth_krb4(const char *server_user, KTEXT auth, char **client)
KTEXT_ST reply; KTEXT_ST reply;
char instance[INST_SZ]; char instance[INST_SZ];
int r, s; int r, s;
socklen_t slen;
u_int cksum; u_int cksum;
Key_schedule schedule; Key_schedule schedule;
struct sockaddr_in local, foreign; struct sockaddr_in local, foreign;
s = packet_get_connection_in(); s = packet_get_connection_in();
r = sizeof(local); slen = sizeof(local);
memset(&local, 0, sizeof(local)); memset(&local, 0, sizeof(local));
if (getsockname(s, (struct sockaddr *) & local, &r) < 0) if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
debug("getsockname failed: %.100s", strerror(errno)); debug("getsockname failed: %.100s", strerror(errno));
r = sizeof(foreign); slen = sizeof(foreign);
memset(&foreign, 0, sizeof(foreign)); memset(&foreign, 0, sizeof(foreign));
if (getpeername(s, (struct sockaddr *) & foreign, &r) < 0) { if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
debug("getpeername failed: %.100s", strerror(errno)); debug("getpeername failed: %.100s", strerror(errno));
fatal_cleanup(); fatal_cleanup();
} }

8
bufaux.c
View File

@ -15,7 +15,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: bufaux.c,v 1.7 1999/11/25 00:54:58 damien Exp $"); RCSID("$Id: bufaux.c,v 1.8 2000/03/17 12:40:15 damien Exp $");
#include "ssh.h" #include "ssh.h"
@ -39,7 +39,7 @@ buffer_put_bignum(Buffer *buffer, BIGNUM *value)
{ {
int bits = BN_num_bits(value); int bits = BN_num_bits(value);
int bin_size = (bits + 7) / 8; int bin_size = (bits + 7) / 8;
char *buf = xmalloc(bin_size); char unsigned *buf = xmalloc(bin_size);
int oi; int oi;
char msg[2]; char msg[2];
@ -53,7 +53,7 @@ buffer_put_bignum(Buffer *buffer, BIGNUM *value)
PUT_16BIT(msg, bits); PUT_16BIT(msg, bits);
buffer_append(buffer, msg, 2); buffer_append(buffer, msg, 2);
/* Store the binary data. */ /* Store the binary data. */
buffer_append(buffer, buf, oi); buffer_append(buffer, (char *)buf, oi);
memset(buf, 0, bin_size); memset(buf, 0, bin_size);
xfree(buf); xfree(buf);
@ -75,7 +75,7 @@ buffer_get_bignum(Buffer *buffer, BIGNUM *value)
bytes = (bits + 7) / 8; bytes = (bits + 7) / 8;
if (buffer_len(buffer) < bytes) if (buffer_len(buffer) < bytes)
fatal("buffer_get_bignum: input buffer too small"); fatal("buffer_get_bignum: input buffer too small");
bin = buffer_ptr(buffer); bin = (unsigned char*) buffer_ptr(buffer);
BN_bin2bn(bin, bytes, value); BN_bin2bn(bin, bytes, value);
buffer_consume(buffer, bytes); buffer_consume(buffer, bytes);

6
channels.c
View File

@ -16,7 +16,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: channels.c,v 1.18 2000/03/11 09:45:41 damien Exp $"); RCSID("$Id: channels.c,v 1.19 2000/03/17 12:40:15 damien Exp $");
#include "ssh.h" #include "ssh.h"
#include "packet.h" #include "packet.h"
@ -1041,7 +1041,7 @@ channel_input_port_open(int payload_len)
int remote_channel, sock = 0, newch, i; int remote_channel, sock = 0, newch, i;
u_short host_port; u_short host_port;
char *host, *originator_string; char *host, *originator_string;
int host_len, originator_len; unsigned int host_len, originator_len;
struct addrinfo hints, *ai, *aitop; struct addrinfo hints, *ai, *aitop;
char ntop[NI_MAXHOST], strport[NI_MAXSERV]; char ntop[NI_MAXHOST], strport[NI_MAXSERV];
int gaierr; int gaierr;
@ -1341,7 +1341,7 @@ x11_input_open(int payload_len)
int remote_channel, display_number, sock = 0, newch; int remote_channel, display_number, sock = 0, newch;
const char *display; const char *display;
char buf[1024], *cp, *remote_host; char buf[1024], *cp, *remote_host;
int remote_len; unsigned int remote_len;
struct addrinfo hints, *ai, *aitop; struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV]; char strport[NI_MAXSERV];
int gaierr; int gaierr;

12
compress.c
View File

@ -14,7 +14,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: compress.c,v 1.3 1999/11/25 00:54:59 damien Exp $"); RCSID("$Id: compress.c,v 1.4 2000/03/17 12:40:16 damien Exp $");
#include "ssh.h" #include "ssh.h"
#include "buffer.h" #include "buffer.h"
@ -75,13 +75,13 @@ buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
return; return;
/* Input is the contents of the input buffer. */ /* Input is the contents of the input buffer. */
outgoing_stream.next_in = buffer_ptr(input_buffer); outgoing_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
outgoing_stream.avail_in = buffer_len(input_buffer); outgoing_stream.avail_in = buffer_len(input_buffer);
/* Loop compressing until deflate() returns with avail_out != 0. */ /* Loop compressing until deflate() returns with avail_out != 0. */
do { do {
/* Set up fixed-size output buffer. */ /* Set up fixed-size output buffer. */
outgoing_stream.next_out = buf; outgoing_stream.next_out = (unsigned char *)buf;
outgoing_stream.avail_out = sizeof(buf); outgoing_stream.avail_out = sizeof(buf);
/* Compress as much data into the buffer as possible. */ /* Compress as much data into the buffer as possible. */
@ -124,10 +124,10 @@ buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
char buf[4096]; char buf[4096];
int status; int status;
incoming_stream.next_in = buffer_ptr(input_buffer); incoming_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
incoming_stream.avail_in = buffer_len(input_buffer); incoming_stream.avail_in = buffer_len(input_buffer);
incoming_stream.next_out = buf; incoming_stream.next_out = (unsigned char *) buf;
incoming_stream.avail_out = sizeof(buf); incoming_stream.avail_out = sizeof(buf);
for (;;) { for (;;) {
@ -136,7 +136,7 @@ buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
case Z_OK: case Z_OK:
buffer_append(output_buffer, buf, buffer_append(output_buffer, buf,
sizeof(buf) - incoming_stream.avail_out); sizeof(buf) - incoming_stream.avail_out);
incoming_stream.next_out = buf; incoming_stream.next_out = (unsigned char *) buf;
incoming_stream.avail_out = sizeof(buf); incoming_stream.avail_out = sizeof(buf);
break; break;
case Z_STREAM_END: case Z_STREAM_END:

4
fingerprint.c
View File

@ -28,7 +28,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: fingerprint.c,v 1.4 1999/11/24 16:15:25 markus Exp $"); RCSID("$Id: fingerprint.c,v 1.5 2000/03/16 20:56:14 markus Exp $");
#include "ssh.h" #include "ssh.h"
#include "xmalloc.h" #include "xmalloc.h"
@ -51,7 +51,7 @@ fingerprint(BIGNUM *e, BIGNUM *n)
static char retval[80]; static char retval[80];
MD5_CTX md; MD5_CTX md;
unsigned char d[16]; unsigned char d[16];
char *buf; unsigned char *buf;
int nlen, elen; int nlen, elen;
nlen = BN_num_bytes(n); nlen = BN_num_bytes(n);

6
packet.h
View File

@ -13,7 +13,7 @@
* *
*/ */
/* RCSID("$Id: packet.h,v 1.9 2000/01/14 04:45:51 damien Exp $"); */ /* RCSID("$Id: packet.h,v 1.10 2000/03/17 12:40:16 damien Exp $"); */
#ifndef PACKET_H #ifndef PACKET_H
#define PACKET_H #define PACKET_H
@ -151,7 +151,7 @@ char *packet_get_string(unsigned int *length_ptr);
* The error message should not contain a newline. The total length of the * The error message should not contain a newline. The total length of the
* message must not exceed 1024 bytes. * message must not exceed 1024 bytes.
*/ */
void packet_disconnect(const char *fmt,...) __attribute__((format(printf, 1, 2)));; void packet_disconnect(const char *fmt,...) __attribute__((format(printf, 1, 2)));
/* /*
* Sends a diagnostic message to the other side. This message can be sent at * Sends a diagnostic message to the other side. This message can be sent at
@ -163,7 +163,7 @@ void packet_disconnect(const char *fmt,...) __attribute__((format(printf, 1,
* remote side protocol flags do not indicate that it supports SSH_MSG_DEBUG, * remote side protocol flags do not indicate that it supports SSH_MSG_DEBUG,
* this will do nothing. * this will do nothing.
*/ */
void packet_send_debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));; void packet_send_debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));
/* Checks if there is any buffered output, and tries to write some of the output. */ /* Checks if there is any buffered output, and tries to write some of the output. */
void packet_write_poll(void); void packet_write_poll(void);

4
radix.c
View File

@ -213,7 +213,7 @@ creds_to_radix(CREDENTIALS *creds, unsigned char *buf)
p += creds->ticket_st.length; p += creds->ticket_st.length;
len = p - temp; len = p - temp;
return (uuencode(temp, len, buf)); return (uuencode((unsigned char *)temp, len, (char *)buf));
} }
int int
@ -225,7 +225,7 @@ radix_to_creds(const char *buf, CREDENTIALS *creds)
char version; char version;
char temp[2048]; char temp[2048];
if (!(len = uudecode(buf, temp, sizeof(temp)))) if (!(len = uudecode(buf, (unsigned char *)temp, sizeof(temp))))
return 0; return 0;
p = temp; p = temp;

6
rsa.c
View File

@ -35,7 +35,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: rsa.c,v 1.10 2000/03/09 10:27:51 damien Exp $"); RCSID("$Id: rsa.c,v 1.11 2000/03/17 12:40:16 damien Exp $");
#include "rsa.h" #include "rsa.h"
#include "ssh.h" #include "ssh.h"
@ -145,7 +145,7 @@ rsa_generate_key(RSA *prv, RSA *pub, unsigned int bits)
void void
rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key) rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
{ {
char *inbuf, *outbuf; unsigned char *inbuf, *outbuf;
int len, ilen, olen; int len, ilen, olen;
if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e)) if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))
@ -173,7 +173,7 @@ rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
void void
rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key) rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
{ {
char *inbuf, *outbuf; unsigned char *inbuf, *outbuf;
int len, ilen, olen; int len, ilen, olen;
olen = BN_num_bytes(key->n); olen = BN_num_bytes(key->n);

6
scp.c
View File

@ -45,7 +45,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: scp.c,v 1.17 2000/03/09 10:27:51 damien Exp $"); RCSID("$Id: scp.c,v 1.18 2000/03/17 12:40:16 damien Exp $");
#include "ssh.h" #include "ssh.h"
#include "xmalloc.h" #include "xmalloc.h"
@ -1008,7 +1008,7 @@ run_err(const char *fmt,...)
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE. * SUCH DAMAGE.
* *
* $Id: scp.c,v 1.17 2000/03/09 10:27:51 damien Exp $ * $Id: scp.c,v 1.18 2000/03/17 12:40:16 damien Exp $
*/ */
char * char *
@ -1120,7 +1120,7 @@ alarmtimer(int wait)
} }
void void
updateprogressmeter(int sig) updateprogressmeter(int ignore)
{ {
int save_errno = errno; int save_errno = errno;

9
ssh-agent.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: ssh-agent.c,v 1.25 2000/01/02 21:51:03 markus Exp $ */ /* $OpenBSD: ssh-agent.c,v 1.26 2000/03/16 20:56:14 markus Exp $ */
/* /*
* Author: Tatu Ylonen <ylo@cs.hut.fi> * Author: Tatu Ylonen <ylo@cs.hut.fi>
@ -9,7 +9,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$OpenBSD: ssh-agent.c,v 1.25 2000/01/02 21:51:03 markus Exp $"); RCSID("$OpenBSD: ssh-agent.c,v 1.26 2000/03/16 20:56:14 markus Exp $");
#include "ssh.h" #include "ssh.h"
#include "rsa.h" #include "rsa.h"
@ -417,6 +417,7 @@ after_select(fd_set *readset, fd_set *writeset)
{ {
unsigned int i; unsigned int i;
int len, sock; int len, sock;
socklen_t slen;
char buf[1024]; char buf[1024];
struct sockaddr_un sunaddr; struct sockaddr_un sunaddr;
@ -426,8 +427,8 @@ after_select(fd_set *readset, fd_set *writeset)
break; break;
case AUTH_SOCKET: case AUTH_SOCKET:
if (FD_ISSET(sockets[i].fd, readset)) { if (FD_ISSET(sockets[i].fd, readset)) {
len = sizeof(sunaddr); slen = sizeof(sunaddr);
sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len); sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
if (sock < 0) { if (sock < 0) {
perror("accept from AUTH_SOCKET"); perror("accept from AUTH_SOCKET");
break; break;

5
ssh-keygen.c
View File

@ -7,7 +7,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: ssh-keygen.c,v 1.11 2000/03/09 10:27:51 damien Exp $"); RCSID("$Id: ssh-keygen.c,v 1.12 2000/03/17 12:40:17 damien Exp $");
#include "rsa.h" #include "rsa.h"
#include "ssh.h" #include "ssh.h"
@ -85,6 +85,7 @@ do_fingerprint(struct passwd *pw)
RSA *public_key; RSA *public_key;
char *comment = NULL, *cp, *ep, line[16*1024]; char *comment = NULL, *cp, *ep, line[16*1024];
int i, skip = 0, num = 1, invalid = 1; int i, skip = 0, num = 1, invalid = 1;
unsigned int ignore;
struct stat st; struct stat st;
if (!have_identity) if (!have_identity)
@ -142,7 +143,7 @@ do_fingerprint(struct passwd *pw)
*cp++ = '\0'; *cp++ = '\0';
} }
ep = cp; ep = cp;
if (auth_rsa_read_key(&cp, &i, e, n)) { if (auth_rsa_read_key(&cp, &ignore, e, n)) {
invalid = 0; invalid = 0;
comment = *cp ? cp : comment; comment = *cp ? cp : comment;
printf("%d %s %s\n", BN_num_bits(n), printf("%d %s %s\n", BN_num_bits(n),

490
ssh.1
View File

@ -9,7 +9,7 @@
.\" .\"
.\" Created: Sat Apr 22 21:55:14 1995 ylo .\" Created: Sat Apr 22 21:55:14 1995 ylo
.\" .\"
.\" $Id: ssh.1,v 1.18 2000/03/09 10:27:52 damien Exp $ .\" $Id: ssh.1,v 1.19 2000/03/17 12:40:17 damien Exp $
.\" .\"
.Dd September 25, 1999 .Dd September 25, 1999
.Dt SSH 1 .Dt SSH 1
@ -52,9 +52,11 @@
.Sh DESCRIPTION .Sh DESCRIPTION
.Nm .Nm
(Secure Shell) is a program for logging into a remote machine and for (Secure Shell) is a program for logging into a remote machine and for
executing commands on a remote machine. It is intended to replace executing commands on a remote machine.
It is intended to replace
rlogin and rsh, and provide secure encrypted communications between rlogin and rsh, and provide secure encrypted communications between
two untrusted hosts over an insecure network. X11 connections and two untrusted hosts over an insecure network.
X11 connections and
arbitrary TCP/IP ports can also be forwarded over the secure channel. arbitrary TCP/IP ports can also be forwarded over the secure channel.
.Pp .Pp
.Nm .Nm
@ -76,15 +78,16 @@ or
exists in the user's home directory on the exists in the user's home directory on the
remote machine and contains a line containing the name of the client remote machine and contains a line containing the name of the client
machine and the name of the user on that machine, the user is machine and the name of the user on that machine, the user is
permitted to log in. This form of authentication alone is normally not permitted to log in.
This form of authentication alone is normally not
allowed by the server because it is not secure. allowed by the server because it is not secure.
.Pp .Pp
The second (and primary) authentication method is the The second (and primary) authentication method is the
.Pa rhosts .Pa rhosts
or or
.Pa hosts.equiv .Pa hosts.equiv
method combined with RSA-based host authentication. It method combined with RSA-based host authentication.
means that if the login would be permitted by It means that if the login would be permitted by
.Pa \&.rhosts , .Pa \&.rhosts ,
.Pa \&.shosts , .Pa \&.shosts ,
.Pa /etc/hosts.equiv , .Pa /etc/hosts.equiv ,
@ -97,10 +100,10 @@ and
.Pa $HOME/.ssh/known_hosts .Pa $HOME/.ssh/known_hosts
in the in the
.Sx FILES .Sx FILES
section), only then login is section), only then login is permitted.
permitted. This authentication method closes security holes due to IP This authentication method closes security holes due to IP
spoofing, DNS spoofing and routing spoofing. [Note to the spoofing, DNS spoofing and routing spoofing.
administrator: [Note to the administrator:
.Pa /etc/hosts.equiv , .Pa /etc/hosts.equiv ,
.Pa \&.rhosts , .Pa \&.rhosts ,
and the rlogin/rsh protocol in general, are inherently insecure and should be and the rlogin/rsh protocol in general, are inherently insecure and should be
@ -112,34 +115,39 @@ supports RSA based authentication.
The scheme is based on public-key cryptography: there are cryptosystems The scheme is based on public-key cryptography: there are cryptosystems
where encryption and decryption are done using separate keys, and it where encryption and decryption are done using separate keys, and it
is not possible to derive the decryption key from the encryption key. is not possible to derive the decryption key from the encryption key.
RSA is one such system. The idea is that each user creates a public/private RSA is one such system.
key pair for authentication purposes. The The idea is that each user creates a public/private
server knows the public key, and only the user knows the private key. key pair for authentication purposes.
The server knows the public key, and only the user knows the private key.
The file The file
.Pa $HOME/.ssh/authorized_keys .Pa $HOME/.ssh/authorized_keys
lists the public keys that are permitted for logging lists the public keys that are permitted for logging
in. When the user logs in, the in.
When the user logs in, the
.Nm .Nm
program tells the server which key pair it would like to use for program tells the server which key pair it would like to use for
authentication. The server checks if this key is permitted, and if authentication.
The server checks if this key is permitted, and if
so, sends the user (actually the so, sends the user (actually the
.Nm .Nm
program running on behalf of the user) a challenge, a random number, program running on behalf of the user) a challenge, a random number,
encrypted by the user's public key. The challenge can only be encrypted by the user's public key.
decrypted using the proper private key. The user's client then decrypts the The challenge can only be
decrypted using the proper private key.
The user's client then decrypts the
challenge using the private key, proving that he/she knows the private challenge using the private key, proving that he/she knows the private
key but without disclosing it to the server. key but without disclosing it to the server.
.Pp .Pp
.Nm .Nm
implements the RSA authentication protocol automatically. The user implements the RSA authentication protocol automatically.
creates his/her RSA key pair by running The user creates his/her RSA key pair by running
.Xr ssh-keygen 1 . .Xr ssh-keygen 1 .
This stores the private key in This stores the private key in
.Pa \&.ssh/identity .Pa \&.ssh/identity
and the public key in and the public key in
.Pa \&.ssh/identity.pub .Pa \&.ssh/identity.pub
in the user's home directory. The user should then in the user's home directory.
copy the The user should then copy the
.Pa identity.pub .Pa identity.pub
to to
.Pa \&.ssh/authorized_keys .Pa \&.ssh/authorized_keys
@ -148,24 +156,28 @@ in his/her home directory on the remote machine (the
file corresponds to the conventional file corresponds to the conventional
.Pa \&.rhosts .Pa \&.rhosts
file, and has one key file, and has one key
per line, though the lines can be very long). After this, the user per line, though the lines can be very long).
can log in without giving the password. RSA authentication is much After this, the user can log in without giving the password.
RSA authentication is much
more secure than rhosts authentication. more secure than rhosts authentication.
.Pp .Pp
The most convenient way to use RSA authentication may be with an The most convenient way to use RSA authentication may be with an
authentication agent. See authentication agent.
See
.Xr ssh-agent 1 .Xr ssh-agent 1
for more information. for more information.
.Pp .Pp
If other authentication methods fail, If other authentication methods fail,
.Nm .Nm
prompts the user for a password. The password is sent to the remote prompts the user for a password.
The password is sent to the remote
host for checking; however, since all communications are encrypted, host for checking; however, since all communications are encrypted,
the password cannot be seen by someone listening on the network. the password cannot be seen by someone listening on the network.
.Pp .Pp
When the user's identity has been accepted by the server, the server When the user's identity has been accepted by the server, the server
either executes the given command, or logs into the machine and gives either executes the given command, or logs into the machine and gives
the user a normal shell on the remote machine. All communication with the user a normal shell on the remote machine.
All communication with
the remote command or shell will be automatically encrypted. the remote command or shell will be automatically encrypted.
.Pp .Pp
If a pseudo-terminal has been allocated (normal login session), the If a pseudo-terminal has been allocated (normal login session), the
@ -182,19 +194,22 @@ the session blocks waiting for forwarded X11 or TCP/IP
connections to terminate, it can be backgrounded with connections to terminate, it can be backgrounded with
.Ic ~& .Ic ~&
(this should not be used while the user shell is active, as it can cause the (this should not be used while the user shell is active, as it can cause the
shell to hang). All available escapes can be listed with shell to hang).
All available escapes can be listed with
.Ic ~? . .Ic ~? .
.Pp .Pp
A single tilde character can be sent as A single tilde character can be sent as
.Ic ~~ .Ic ~~
(or by following the tilde by a character other than those described above). (or by following the tilde by a character other than those described above).
The escape character must always follow a newline to be interpreted as The escape character must always follow a newline to be interpreted as
special. The escape character can be changed in configuration files special.
The escape character can be changed in configuration files
or on the command line. or on the command line.
.Pp .Pp
If no pseudo tty has been allocated, the If no pseudo tty has been allocated, the
session is transparent and can be used to reliably transfer binary session is transparent and can be used to reliably transfer binary
data. On most systems, setting the escape character to data.
On most systems, setting the escape character to
.Dq none .Dq none
will also make the session transparent even if a tty is used. will also make the session transparent even if a tty is used.
.Pp .Pp
@ -210,7 +225,8 @@ environment variable is set), the connection to the X11 display is
automatically forwarded to the remote side in such a way that any X11 automatically forwarded to the remote side in such a way that any X11
programs started from the shell (or command) will go through the programs started from the shell (or command) will go through the
encrypted channel, and the connection to the real X server will be made encrypted channel, and the connection to the real X server will be made
from the local machine. The user should not manually set from the local machine.
The user should not manually set
.Ev DISPLAY . .Ev DISPLAY .
Forwarding of X11 connections can be Forwarding of X11 connections can be
configured on the command line or in configuration files. configured on the command line or in configuration files.
@ -220,7 +236,8 @@ The
value set by value set by
.Nm .Nm
will point to the server machine, but with a display number greater will point to the server machine, but with a display number greater
than zero. This is normal, and happens because than zero.
This is normal, and happens because
.Nm .Nm
creates a creates a
.Dq proxy .Dq proxy
@ -232,7 +249,8 @@ will also automatically set up Xauthority data on the server machine.
For this purpose, it will generate a random authorization cookie, For this purpose, it will generate a random authorization cookie,
store it in Xauthority on the server, and verify that any forwarded store it in Xauthority on the server, and verify that any forwarded
connections carry this cookie and replace it by the real cookie when connections carry this cookie and replace it by the real cookie when
the connection is opened. The real authentication cookie is never the connection is opened.
The real authentication cookie is never
sent to the server machine (and no cookies are sent in the plain). sent to the server machine (and no cookies are sent in the plain).
.Pp .Pp
If the user is using an authentication agent, the connection to the agent If the user is using an authentication agent, the connection to the agent
@ -240,25 +258,29 @@ is automatically forwarded to the remote side unless disabled on
command line or in a configuration file. command line or in a configuration file.
.Pp .Pp
Forwarding of arbitrary TCP/IP connections over the secure channel can Forwarding of arbitrary TCP/IP connections over the secure channel can
be specified either on command line or in a configuration file. One be specified either on command line or in a configuration file.
possible application of TCP/IP forwarding is a secure connection to an One possible application of TCP/IP forwarding is a secure connection to an
electronic purse; another is going trough firewalls. electronic purse; another is going trough firewalls.
.Pp .Pp
.Nm .Nm
automatically maintains and checks a database containing RSA-based automatically maintains and checks a database containing RSA-based
identifications for all hosts it has ever been used with. The identifications for all hosts it has ever been used with.
database is stored in The database is stored in
.Pa \&.ssh/known_hosts .Pa \&.ssh/known_hosts
in the user's home directory. Additionally, the file in the user's home directory.
Additionally, the file
.Pa /etc/ssh_known_hosts .Pa /etc/ssh_known_hosts
is automatically checked for known hosts. Any new hosts are is automatically checked for known hosts.
automatically added to the user's file. If a host's identification Any new hosts are automatically added to the user's file.
If a host's identification
ever changes, ever changes,
.Nm .Nm
warns about this and disables password authentication to prevent a warns about this and disables password authentication to prevent a
trojan horse from getting the user's password. Another purpose of trojan horse from getting the user's password.
Another purpose of
this mechanism is to prevent man-in-the-middle attacks which could this mechanism is to prevent man-in-the-middle attacks which could
otherwise be used to circumvent the encryption. The otherwise be used to circumvent the encryption.
The
.Cm StrictHostKeyChecking .Cm StrictHostKeyChecking
option (see below) can be used to prevent logins to machines whose option (see below) can be used to prevent logins to machines whose
host key is not known or has changed. host key is not known or has changed.
@ -270,7 +292,8 @@ also be specified on a per-host basis in the configuration file.
.It Fl c Ar blowfish|3des .It Fl c Ar blowfish|3des
Selects the cipher to use for encrypting the session. Selects the cipher to use for encrypting the session.
.Ar 3des .Ar 3des
is used by default. It is believed to be secure. is used by default.
It is believed to be secure.
.Ar 3des .Ar 3des
(triple-des) is an encrypt-decrypt-encrypt triple with three different keys. (triple-des) is an encrypt-decrypt-encrypt triple with three different keys.
It is presumably more secure than the It is presumably more secure than the
@ -282,22 +305,24 @@ is a fast block cipher, it appears very secure and is much faster than
.It Fl e Ar ch|^ch|none .It Fl e Ar ch|^ch|none
Sets the escape character for sessions with a pty (default: Sets the escape character for sessions with a pty (default:
.Ql ~ ) . .Ql ~ ) .
The escape character is only recognized at the beginning of a line. The The escape character is only recognized at the beginning of a line.
escape character followed by a dot The escape character followed by a dot
.Pq Ql \&. .Pq Ql \&.
closes the connection, followed closes the connection, followed
by control-Z suspends the connection, and followed by itself sends the by control-Z suspends the connection, and followed by itself sends the
escape character once. Setting the character to escape character once.
Setting the character to
.Dq none .Dq none
disables any escapes and makes the session fully transparent. disables any escapes and makes the session fully transparent.
.It Fl f .It Fl f
Requests Requests
.Nm .Nm
to go to background just before command execution. This is useful to go to background just before command execution.
if This is useful if
.Nm .Nm
is going to ask for passwords or passphrases, but the user is going to ask for passwords or passphrases, but the user
wants it in the background. This implies wants it in the background.
This implies
.Fl n . .Fl n .
The recommended way to start X11 programs at a remote site is with The recommended way to start X11 programs at a remote site is with
something like something like
@ -306,11 +331,13 @@ something like
Allows remote hosts to connect to local forwarded ports. Allows remote hosts to connect to local forwarded ports.
.It Fl i Ar identity_file .It Fl i Ar identity_file
Selects the file from which the identity (private key) for Selects the file from which the identity (private key) for
RSA authentication is read. Default is RSA authentication is read.
Default is
.Pa \&.ssh/identity .Pa \&.ssh/identity
in the user's home directory. Identity files may also be specified on in the user's home directory.
a per-host basis in the configuration file. It is possible to have Identity files may also be specified on
multiple a per-host basis in the configuration file.
It is possible to have multiple
.Fl i .Fl i
options (and multiple identities specified in options (and multiple identities specified in
configuration files). configuration files).
@ -318,16 +345,17 @@ configuration files).
Disables forwarding of Kerberos tickets and AFS tokens. This may Disables forwarding of Kerberos tickets and AFS tokens. This may
also be specified on a per-host basis in the configuration file. also be specified on a per-host basis in the configuration file.
.It Fl l Ar login_name .It Fl l Ar login_name
Specifies the user to log in as on the remote machine. This may also Specifies the user to log in as on the remote machine.
be specified on a per-host basis in the configuration file. This also may be specified on a per-host basis in the configuration file.
.It Fl n .It Fl n
Redirects stdin from Redirects stdin from
.Pa /dev/null .Pa /dev/null
(actually, prevents reading from stdin). (actually, prevents reading from stdin).
This must be used when This must be used when
.Nm .Nm
is run in the background. A common trick is to use this to run X11 is run in the background.
programs in a remote machine. For example, A common trick is to use this to run X11 programs on a remote machine.
For example,
.Ic ssh -n shadows.cs.hut.fi emacs & .Ic ssh -n shadows.cs.hut.fi emacs &
will start an emacs on shadows.cs.hut.fi, and the X11 will start an emacs on shadows.cs.hut.fi, and the X11
connection will be automatically forwarded over an encrypted channel. connection will be automatically forwarded over an encrypted channel.
@ -342,10 +370,11 @@ option.)
.It Fl o Ar option .It Fl o Ar option
Can be used to give options in the format used in the config file. Can be used to give options in the format used in the config file.
This is useful for specifying options for which there is no separate This is useful for specifying options for which there is no separate
command-line flag. The option has the same format as a line in the command-line flag.
configuration file. The option has the same format as a line in the configuration file.
.It Fl p Ar port .It Fl p Ar port
Port to connect to on the remote host. This can be specified on a Port to connect to on the remote host.
This can be specified on a
per-host basis in the configuration file. per-host basis in the configuration file.
.It Fl P .It Fl P
Use a non-privileged port for outgoing connections. Use a non-privileged port for outgoing connections.
@ -356,35 +385,40 @@ Note that this option turns off
and and
.Cm RhostsRSAAuthentication . .Cm RhostsRSAAuthentication .
.It Fl q .It Fl q
Quiet mode. Causes all warning and diagnostic messages to be Quiet mode.
suppressed. Only fatal errors are displayed. Causes all warning and diagnostic messages to be suppressed.
Only fatal errors are displayed.
.It Fl t .It Fl t
Force pseudo-tty allocation. This can be used to execute arbitary Force pseudo-tty allocation.
screen-based programs on a remote machine, which can be very useful This can be used to execute arbitary
e.g. when implementing menu services. screen-based programs on a remote machine, which can be very useful,
e.g., when implementing menu services.
.It Fl v .It Fl v
Verbose mode. Causes Verbose mode.
Causes
.Nm .Nm
to print debugging messages about its progress. This is helpful in to print debugging messages about its progress.
This is helpful in
debugging connection, authentication, and configuration problems. debugging connection, authentication, and configuration problems.
The verbose mode is also used to display The verbose mode is also used to display
.Xr skey 1 .Xr skey 1
challenges, if the user entered "s/key" as password. challenges, if the user entered "s/key" as password.
.It Fl x .It Fl x
Disables X11 forwarding. This can also be specified on a per-host Disables X11 forwarding.
basis in a configuration file. This can also be specified on a per-host basis in a configuration file.
.It Fl X .It Fl X
Enables X11 forwarding. Enables X11 forwarding.
.It Fl C .It Fl C
Requests compression of all data (including stdin, stdout, stderr, and Requests compression of all data (including stdin, stdout, stderr, and
data for forwarded X11 and TCP/IP connections). The compression data for forwarded X11 and TCP/IP connections).
algorithm is the same used by The compression algorithm is the same used by
.Xr gzip 1 , .Xr gzip 1 ,
and the and the
.Dq level .Dq level
can be controlled by the can be controlled by the
.Cm CompressionLevel .Cm CompressionLevel
option (see below). Compression is desirable on modem lines and other option (see below).
Compression is desirable on modem lines and other
slow connections, but will only slow down things on fast networks. slow connections, but will only slow down things on fast networks.
The default value can be set on a host-by-host basis in the The default value can be set on a host-by-host basis in the
configuration files; see the configuration files; see the
@ -392,8 +426,8 @@ configuration files; see the
option below. option below.
.It Fl L Ar port:host:hostport .It Fl L Ar port:host:hostport
Specifies that the given port on the local (client) host is to be Specifies that the given port on the local (client) host is to be
forwarded to the given host and port on the remote side. This works forwarded to the given host and port on the remote side.
by allocating a socket to listen to This works by allocating a socket to listen to
.Ar port .Ar port
on the local side, and whenever a connection is made to this port, the on the local side, and whenever a connection is made to this port, the
connection is forwarded over the secure channel, and a connection is connection is forwarded over the secure channel, and a connection is
@ -401,14 +435,15 @@ made to
.Ar host .Ar host
port port
.Ar hostport .Ar hostport
from the remote machine. Port forwardings can also be specified in the from the remote machine.
configuration file. Only root can forward privileged ports. Port forwardings can also be specified in the configuration file.
Only root can forward privileged ports.
IPv6 addresses can be specified with an alternative syntax: IPv6 addresses can be specified with an alternative syntax:
.Ar port/host/hostport .Ar port/host/hostport
.It Fl R Ar port:host:hostport .It Fl R Ar port:host:hostport
Specifies that the given port on the remote (server) host is to be Specifies that the given port on the remote (server) host is to be
forwarded to the given host and port on the local side. This works forwarded to the given host and port on the local side.
by allocating a socket to listen to This works by allocating a socket to listen to
.Ar port .Ar port
on the remote side, and whenever a connection is made to this port, the on the remote side, and whenever a connection is made to this port, the
connection is forwarded over the secure channel, and a connection is connection is forwarded over the secure channel, and a connection is
@ -416,8 +451,9 @@ made to
.Ar host .Ar host
port port
.Ar hostport .Ar hostport
from the local machine. Port forwardings can also be specified in the from the local machine.
configuration file. Privileged ports can be forwarded only when Port forwardings can also be specified in the configuration file.
Privileged ports can be forwarded only when
logging in as root on the remote machine. logging in as root on the remote machine.
.It Fl 4 .It Fl 4
Forces Forces
@ -436,10 +472,12 @@ command line options, user's configuration file
and system-wide configuration file and system-wide configuration file
.Pq Pa /etc/ssh_config . .Pq Pa /etc/ssh_config .
For each parameter, the first obtained value For each parameter, the first obtained value
will be used. The configuration files contain sections bracketed by will be used.
"Host" specifications, and that section is only applied for hosts that The configuration files contain sections bracketed by
match one of the patterns given in the specification. The matched .Dq Host
host name is the one given on the command line. specifications, and that section is only applied for hosts that
match one of the patterns given in the specification.
The matched host name is the one given on the command line.
.Pp .Pp
Since the first obtained value for each parameter is used, more Since the first obtained value for each parameter is used, more
host-specific declarations should be given near the beginning of the host-specific declarations should be given near the beginning of the
@ -466,10 +504,12 @@ given after the keyword.
and and
.Ql ? .Ql ?
can be used as wildcards in the can be used as wildcards in the
patterns. A single patterns.
A single
.Ql \&* .Ql \&*
as a pattern can be used to provide global as a pattern can be used to provide global
defaults for all hosts. The host is the defaults for all hosts.
The host is the
.Ar hostname .Ar hostname
argument given on the command line (i.e., the name is not converted to argument given on the command line (i.e., the name is not converted to
a canonicalized host name before matching). a canonicalized host name before matching).
@ -482,9 +522,10 @@ or
.It Cm BatchMode .It Cm BatchMode
If set to If set to
.Dq yes , .Dq yes ,
passphrase/password querying will be disabled. This passphrase/password querying will be disabled.
option is useful in scripts and other batch jobs where you have no This option is useful in scripts and other batch jobs where you have no
user to supply the password. The argument must be user to supply the password.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -498,33 +539,37 @@ If the option is set to
.Dq no , .Dq no ,
the check will not be executed. the check will not be executed.
.It Cm Cipher .It Cm Cipher
Specifies the cipher to use for encrypting the session. Currently, Specifies the cipher to use for encrypting the session.
Currently,
.Dq blowfish , .Dq blowfish ,
and and
.Dq 3des .Dq 3des
are supported. The default is are supported.
The default is
.Dq 3des . .Dq 3des .
.It Cm Compression .It Cm Compression
Specifies whether to use compression. The argument must be Specifies whether to use compression.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
.It Cm CompressionLevel .It Cm CompressionLevel
Specifies the compression level to use if compression is enable. The Specifies the compression level to use if compression is enable.
argument must be an integer from 1 (fast) to 9 (slow, best). The The argument must be an integer from 1 (fast) to 9 (slow, best).
default level is 6, which is good for most applications. The meaning The default level is 6, which is good for most applications.
of the values is the same as in The meaning of the values is the same as in
.Xr gzip 1 . .Xr gzip 1 .
.It Cm ConnectionAttempts .It Cm ConnectionAttempts
Specifies the number of tries (one per second) to make before falling Specifies the number of tries (one per second) to make before falling
back to rsh or exiting. The argument must be an integer. This may be back to rsh or exiting.
useful in scripts if the connection sometimes fails. The argument must be an integer.
This may be useful in scripts if the connection sometimes fails.
.It Cm EscapeChar .It Cm EscapeChar
Sets the escape character (default: Sets the escape character (default:
.Ql ~ ) . .Ql ~ ) .
The escape character can also The escape character can also
be set on the command line. The argument should be a single be set on the command line.
character, The argument should be a single character,
.Ql ^ .Ql ^
followed by a letter, or followed by a letter, or
.Dq none .Dq none
@ -539,13 +584,15 @@ fails due to a connection refused error (there is no
listening on the remote host), listening on the remote host),
.Xr rsh 1 .Xr rsh 1
should automatically be used instead (after a suitable warning about should automatically be used instead (after a suitable warning about
the session being unencrypted). The argument must be the session being unencrypted).
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
.It Cm ForwardAgent .It Cm ForwardAgent
Specifies whether the connection to the authentication agent (if any) Specifies whether the connection to the authentication agent (if any)
will be forwarded to the remote machine. The argument must be will be forwarded to the remote machine.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -553,7 +600,8 @@ or
Specifies whether X11 connections will be automatically redirected Specifies whether X11 connections will be automatically redirected
over the secure channel and over the secure channel and
.Ev DISPLAY .Ev DISPLAY
set. The argument must be set.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -572,10 +620,10 @@ The default is
Specifies a file to use instead of Specifies a file to use instead of
.Pa /etc/ssh_known_hosts . .Pa /etc/ssh_known_hosts .
.It Cm HostName .It Cm HostName
Specifies the real host name to log into. This can be used to specify Specifies the real host name to log into.
nicnames or abbreviations for hosts. Default is the name given on the This can be used to specify nicknames or abbreviations for hosts.
command line. Numeric IP addresses are also permitted (both on the Default is the name given on the command line.
command line and in Numeric IP addresses are also permitted (both on the command line and in
.Cm HostName .Cm HostName
specifications). specifications).
.It Cm IdentityFile .It Cm IdentityFile
@ -584,22 +632,26 @@ is read (default
.Pa .ssh/identity .Pa .ssh/identity
in the user's home directory). in the user's home directory).
Additionally, any identities represented by the authentication agent Additionally, any identities represented by the authentication agent
will be used for authentication. The file name may use the tilde will be used for authentication.
syntax to refer to a user's home directory. It is possible to have The file name may use the tilde
syntax to refer to a user's home directory.
It is possible to have
multiple identity files specified in configuration files; all these multiple identity files specified in configuration files; all these
identities will be tried in sequence. identities will be tried in sequence.
.It Cm KeepAlive .It Cm KeepAlive
Specifies whether the system should send keepalive messages to the Specifies whether the system should send keepalive messages to the
other side. If they are sent, death of the connection or crash of one other side.
of the machines will be properly noticed. However, this means that If they are sent, death of the connection or crash of one
of the machines will be properly noticed.
However, this means that
connections will die if the route is down temporarily, and some people connections will die if the route is down temporarily, and some people
find it annoying. find it annoying.
.Pp .Pp
The default is The default is
.Dq yes .Dq yes
(to send keepalives), and the client will notice (to send keepalives), and the client will notice
if the network goes down or the remote host dies. This is important if the network goes down or the remote host dies.
in scripts, and many users want it too. This is important in scripts, and many users want it too.
.Pp .Pp
To disable keepalives, the value should be set to To disable keepalives, the value should be set to
.Dq no .Dq no
@ -619,11 +671,12 @@ or
.Dq no . .Dq no .
.It Cm LocalForward .It Cm LocalForward
Specifies that a TCP/IP port on the local machine be forwarded over Specifies that a TCP/IP port on the local machine be forwarded over
the secure channel to given host:port from the remote machine. The the secure channel to given host:port from the remote machine.
first argument must be a port number, and the second must be The first argument must be a port number, and the second must be
host:port. Multiple forwardings may be specified, and additional host:port.
forwardings can be given on the command line. Only the root can Multiple forwardings may be specified, and additional
forward privileged ports. forwardings can be given on the command line.
Only the superuser can forward privileged ports.
.It Cm LogLevel .It Cm LogLevel
Gives the verbosity level that is used when logging messages from Gives the verbosity level that is used when logging messages from
.Nm ssh . .Nm ssh .
@ -634,25 +687,33 @@ The default is INFO.
Specifies the number of password prompts before giving up. The Specifies the number of password prompts before giving up. The
argument to this keyword must be an integer. Default is 3. argument to this keyword must be an integer. Default is 3.
.It Cm PasswordAuthentication .It Cm PasswordAuthentication
Specifies whether to use password authentication. The argument to Specifies whether to use password authentication.
this keyword must be The argument to this keyword must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
.It Cm Port .It Cm Port
Specifies the port number to connect on the remote host. Default is Specifies the port number to connect on the remote host.
22. Default is 22.
.It Cm ProxyCommand .It Cm ProxyCommand
Specifies the command to use to connect to the server. The command Specifies the command to use to connect to the server.
string extends to the end of the line, and is executed with /bin/sh. The command
In the command string, %h will be substituted by the host name to string extends to the end of the line, and is executed with
connect and %p by the port. The command can be basically anything, .Pa /bin/sh .
and should read from its stdin and write to its stdout. It should In the command string,
eventually connect an .Ql %h
will be substituted by the host name to
connect and
.Ql %p
by the port.
The command can be basically anything,
and should read from its standard input and write to its standard output.
It should eventually connect an
.Xr sshd 8 .Xr sshd 8
server running on some machine, or execute server running on some machine, or execute
.Ic sshd -i .Ic sshd -i
somewhere. Host key management will be done using the somewhere.
Host key management will be done using the
HostName of the host being connected (defaulting to the name typed by HostName of the host being connected (defaulting to the name typed by
the user). the user).
Note that Note that
@ -661,32 +722,37 @@ is not available for connects with a proxy command.
.Pp .Pp
.It Cm RemoteForward .It Cm RemoteForward
Specifies that a TCP/IP port on the remote machine be forwarded over Specifies that a TCP/IP port on the remote machine be forwarded over
the secure channel to given host:port from the local machine. The the secure channel to given host:port from the local machine.
first argument must be a port number, and the second must be The first argument must be a port number, and the second must be
host:port. Multiple forwardings may be specified, and additional host:port.
forwardings can be given on the command line. Only the root can Multiple forwardings may be specified, and additional
forward privileged ports. forwardings can be given on the command line.
Only the superuser can forward privileged ports.
.It Cm RhostsAuthentication .It Cm RhostsAuthentication
Specifies whether to try rhosts based authentication. Note that this Specifies whether to try rhosts based authentication.
Note that this
declaration only affects the client side and has no effect whatsoever declaration only affects the client side and has no effect whatsoever
on security. Disabling rhosts authentication may reduce on security.
Disabling rhosts authentication may reduce
authentication time on slow connections when rhosts authentication is authentication time on slow connections when rhosts authentication is
not used. Most servers do not permit RhostsAuthentication because it not used.
is not secure (see RhostsRSAAuthentication). The argument to this Most servers do not permit RhostsAuthentication because it
keyword must be is not secure (see RhostsRSAAuthentication).
The argument to this keyword must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
.It Cm RhostsRSAAuthentication .It Cm RhostsRSAAuthentication
Specifies whether to try rhosts based authentication with RSA host Specifies whether to try rhosts based authentication with RSA host
authentication. This is the primary authentication method for most authentication.
sites. The argument must be This is the primary authentication method for most sites.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
.It Cm RSAAuthentication .It Cm RSAAuthentication
Specifies whether to try RSA authentication. The argument to this Specifies whether to try RSA authentication.
keyword must be The argument to this keyword must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -696,8 +762,8 @@ running.
.It Cm SkeyAuthentication .It Cm SkeyAuthentication
Specifies whether to use Specifies whether to use
.Xr skey 1 .Xr skey 1
authentication. The argument to authentication.
this keyword must be The argument to this keyword must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -709,16 +775,19 @@ If this flag is set to
.Nm .Nm
ssh will never automatically add host keys to the ssh will never automatically add host keys to the
.Pa $HOME/.ssh/known_hosts .Pa $HOME/.ssh/known_hosts
file, and refuses to connect hosts whose host key has changed. This file, and refuses to connect hosts whose host key has changed.
provides maximum protection against trojan horse attacks. However, it This provides maximum protection against trojan horse attacks.
can be somewhat annoying if you don't have good However, it can be somewhat annoying if you don't have good
.Pa /etc/ssh_known_hosts .Pa /etc/ssh_known_hosts
files installed and frequently files installed and frequently
connect new hosts. Basically this option forces the user to manually connect new hosts.
add any new hosts. Normally this option is disabled, and new hosts Basically this option forces the user to manually
will automatically be added to the known host files. The host keys of add any new hosts.
known hosts will be verified automatically in either case. The Normally this option is disabled, and new hosts
argument must be will automatically be added to the known host files.
The host keys of
known hosts will be verified automatically in either case.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -737,23 +806,26 @@ turns off
and and
.Cm RhostsRSAAuthentication . .Cm RhostsRSAAuthentication .
.It Cm User .It Cm User
Specifies the user to log in as. This can be useful if you have a Specifies the user to log in as.
different user name in different machines. This saves the trouble of This can be useful if you have a different user name on different machines.
This saves the trouble of
having to remember to give the user name on the command line. having to remember to give the user name on the command line.
.It Cm UserKnownHostsFile .It Cm UserKnownHostsFile
Specifies a file to use instead of Specifies a file to use instead of
.Pa $HOME/.ssh/known_hosts . .Pa $HOME/.ssh/known_hosts .
.It Cm UseRsh .It Cm UseRsh
Specifies that rlogin/rsh should be used for this host. It is Specifies that rlogin/rsh should be used for this host.
possible that the host does not at all support the It is possible that the host does not at all support the
.Nm .Nm
protocol. This causes protocol.
This causes
.Nm .Nm
to immediately exec to immediately execute
.Xr rsh 1 . .Xr rsh 1 .
All other options (except All other options (except
.Cm HostName ) .Cm HostName )
are ignored if this has been specified. The argument must be are ignored if this has been specified.
The argument must be
.Dq yes .Dq yes
or or
.Dq no . .Dq no .
@ -764,15 +836,17 @@ will normally set the following environment variables:
.It Ev DISPLAY .It Ev DISPLAY
The The
.Ev DISPLAY .Ev DISPLAY
variable indicates the location of the X11 server. It is variable indicates the location of the X11 server.
automatically set by It is automatically set by
.Nm .Nm
to point to a value of the form to point to a value of the form
.Dq hostname:n .Dq hostname:n
where hostname indicates where hostname indicates
the host where the shell runs, and n is an integer >= 1. Ssh uses the host where the shell runs, and n is an integer >= 1.
this special value to forward X11 connections over the secure .Nm
channel. The user should normally not set DISPLAY explicitly, as that uses this special value to forward X11 connections over the secure
channel.
The user should normally not set DISPLAY explicitly, as that
will render the X11 connection insecure (and will require the user to will render the X11 connection insecure (and will require the user to
manually copy any required authorization cookies). manually copy any required authorization cookies).
.It Ev HOME .It Ev HOME
@ -792,12 +866,14 @@ as specified when compiling
indicates the path of a unix-domain socket used to communicate with the indicates the path of a unix-domain socket used to communicate with the
agent. agent.
.It Ev SSH_CLIENT .It Ev SSH_CLIENT
Identifies the client end of the connection. The variable contains Identifies the client end of the connection.
The variable contains
three space-separated values: client ip-address, client port number, three space-separated values: client ip-address, client port number,
and server port number. and server port number.
.It Ev SSH_TTY .It Ev SSH_TTY
This is set to the name of the tty (path to the device) associated This is set to the name of the tty (path to the device) associated
with the current shell or command. If the current session has no tty, with the current shell or command.
If the current session has no tty,
this variable is not set. this variable is not set.
.It Ev TZ .It Ev TZ
The timezone variable is set to indicate the present timezone if it The timezone variable is set to indicate the present timezone if it
@ -823,7 +899,8 @@ in
See See
.Xr sshd 8 . .Xr sshd 8 .
.It Pa $HOME/.ssh/identity .It Pa $HOME/.ssh/identity
Contains the RSA authentication identity of the user. This file Contains the RSA authentication identity of the user.
This file
contains sensitive data and should be readable by the user but not contains sensitive data and should be readable by the user but not
accessible by others (read/write/execute). accessible by others (read/write/execute).
Note that Note that
@ -834,39 +911,50 @@ generating the key; the passphrase will be used to encrypt the
sensitive part of this file using 3DES. sensitive part of this file using 3DES.
.It Pa $HOME/.ssh/identity.pub .It Pa $HOME/.ssh/identity.pub
Contains the public key for authentication (public part of the Contains the public key for authentication (public part of the
identity file in human-readable form). The contents of this file identity file in human-readable form).
should be added to The contents of this file should be added to
.Pa $HOME/.ssh/authorized_keys .Pa $HOME/.ssh/authorized_keys
on all machines on all machines
where you wish to log in using RSA authentication. This file is not where you wish to log in using RSA authentication.
sensitive and can (but need not) be readable by anyone. This file is This file is not
sensitive and can (but need not) be readable by anyone.
This file is
never used automatically and is not necessary; it is only provided for never used automatically and is not necessary; it is only provided for
the convenience of the user. the convenience of the user.
.It Pa $HOME/.ssh/config .It Pa $HOME/.ssh/config
This is the per-user configuration file. The format of this file is This is the per-user configuration file.
described above. This file is used by the The format of this file is described above.
This file is used by the
.Nm .Nm
client. This file does not usually contain any sensitive information, client.
This file does not usually contain any sensitive information,
but the recommended permissions are read/write for the user, and not but the recommended permissions are read/write for the user, and not
accessible by others. accessible by others.
.It Pa $HOME/.ssh/authorized_keys .It Pa $HOME/.ssh/authorized_keys
Lists the RSA keys that can be used for logging in as this user. The Lists the RSA keys that can be used for logging in as this user.
format of this file is described in the The format of this file is described in the
.Xr sshd 8 .Xr sshd 8
manual page. In the simplest form the format is the same as the .pub manual page.
In the simplest form the format is the same as the .pub
identity files (that is, each line contains the number of bits in identity files (that is, each line contains the number of bits in
modulus, public exponent, modulus, and comment fields, separated by modulus, public exponent, modulus, and comment fields, separated by
spaces). This file is not highly sensitive, but the recommended spaces).
This file is not highly sensitive, but the recommended
permissions are read/write for the user, and not accessible by others. permissions are read/write for the user, and not accessible by others.
.It Pa /etc/ssh_known_hosts .It Pa /etc/ssh_known_hosts
Systemwide list of known host keys. This file should be prepared by the Systemwide list of known host keys.
This file should be prepared by the
system administrator to contain the public host keys of all machines in the system administrator to contain the public host keys of all machines in the
organization. This file should be world-readable. This file contains organization.
This file should be world-readable.
This file contains
public keys, one per line, in the following format (fields separated public keys, one per line, in the following format (fields separated
by spaces): system name, number of bits in modulus, public exponent, by spaces): system name, number of bits in modulus, public exponent,
modulus, and optional comment field. When different names are used modulus, and optional comment field.
When different names are used
for the same machine, all such names should be listed, separated by for the same machine, all such names should be listed, separated by
commas. The format is described on the commas.
The format is described on the
.Xr sshd 8 .Xr sshd 8
manual page. manual page.
.Pp .Pp
@ -878,32 +966,37 @@ does not convert the user-supplied name to a canonical name before
checking the key, because someone with access to the name servers checking the key, because someone with access to the name servers
would then be able to fool host authentication. would then be able to fool host authentication.
.It Pa /etc/ssh_config .It Pa /etc/ssh_config
Systemwide configuration file. This file provides defaults for those Systemwide configuration file.
This file provides defaults for those
values that are not specified in the user's configuration file, and values that are not specified in the user's configuration file, and
for those users who do not have a configuration file. This file must for those users who do not have a configuration file.
be world-readable. This file must be world-readable.
.It Pa $HOME/.rhosts .It Pa $HOME/.rhosts
This file is used in This file is used in
.Pa \&.rhosts .Pa \&.rhosts
authentication to list the authentication to list the
host/user pairs that are permitted to log in. (Note that this file is host/user pairs that are permitted to log in.
(Note that this file is
also used by rlogin and rsh, which makes using this file insecure.) also used by rlogin and rsh, which makes using this file insecure.)
Each line of the file contains a host name (in the canonical form Each line of the file contains a host name (in the canonical form
returned by name servers), and then a user name on that host, returned by name servers), and then a user name on that host,
separated by a space. One some machines this file may need to be separated by a space.
One some machines this file may need to be
world-readable if the user's home directory is on a NFS partition, world-readable if the user's home directory is on a NFS partition,
because because
.Xr sshd 8 .Xr sshd 8
reads it as root. Additionally, this file must be owned by the user, reads it as root.
and must not have write permissions for anyone else. The recommended Additionally, this file must be owned by the user,
and must not have write permissions for anyone else.
The recommended
permission for most machines is read/write for the user, and not permission for most machines is read/write for the user, and not
accessible by others. accessible by others.
.Pp .Pp
Note that by default Note that by default
.Xr sshd 8 .Xr sshd 8
will be installed so that it requires successful RSA host will be installed so that it requires successful RSA host
authentication before permitting \s+2.\s0rhosts authentication. If your authentication before permitting \s+2.\s0rhosts authentication.
server machine does not have the client's host key in If your server machine does not have the client's host key in
.Pa /etc/ssh_known_hosts , .Pa /etc/ssh_known_hosts ,
you can store it in you can store it in
.Pa $HOME/.ssh/known_hosts . .Pa $HOME/.ssh/known_hosts .
@ -923,14 +1016,18 @@ or
.Xr rsh 1 . .Xr rsh 1 .
.It Pa /etc/hosts.equiv .It Pa /etc/hosts.equiv
This file is used during This file is used during
.Pa \&.rhosts authentication. It contains .Pa \&.rhosts authentication.
It contains
canonical hosts names, one per line (the full format is described on canonical hosts names, one per line (the full format is described on
the the
.Xr sshd 8 .Xr sshd 8
manual page). If the client host is found in this file, login is manual page).
If the client host is found in this file, login is
automatically permitted provided client and server user names are the automatically permitted provided client and server user names are the
same. Additionally, successful RSA host authentication is normally same.
required. This file should only be writable by root. Additionally, successful RSA host authentication is normally
required.
This file should only be writable by root.
.It Pa /etc/shosts.equiv .It Pa /etc/shosts.equiv
This file is processed exactly as This file is processed exactly as
.Pa /etc/hosts.equiv . .Pa /etc/hosts.equiv .
@ -962,7 +1059,8 @@ is required for proper operation.
.Sh AUTHOR .Sh AUTHOR
OpenSSH OpenSSH
is a derivative of the original (free) ssh 1.2.12 release by Tatu Ylonen, is a derivative of the original (free) ssh 1.2.12 release by Tatu Ylonen,
but with bugs removed and newer features re-added. Rapidly after the but with bugs removed and newer features re-added.
Rapidly after the
1.2.12 release, newer versions of the original ssh bore successively 1.2.12 release, newer versions of the original ssh bore successively
more restrictive licenses, and thus demand for a free version was born. more restrictive licenses, and thus demand for a free version was born.
This version of OpenSSH This version of OpenSSH

30
sshconnect.c
View File

@ -8,7 +8,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$OpenBSD: sshconnect.c,v 1.56 2000/02/18 08:50:33 markus Exp $"); RCSID("$OpenBSD: sshconnect.c,v 1.57 2000/03/16 20:56:14 markus Exp $");
#ifdef HAVE_OPENSSL #ifdef HAVE_OPENSSL
#include <openssl/bn.h> #include <openssl/bn.h>
@ -638,6 +638,7 @@ try_kerberos_authentication()
char *realm; char *realm;
CREDENTIALS cred; CREDENTIALS cred;
int r, type, plen; int r, type, plen;
socklen_t slen;
Key_schedule schedule; Key_schedule schedule;
u_long checksum, cksum; u_long checksum, cksum;
MSG_DAT msg_data; MSG_DAT msg_data;
@ -680,16 +681,16 @@ try_kerberos_authentication()
/* Zero the buffer. */ /* Zero the buffer. */
(void) memset(auth.dat, 0, MAX_KTXT_LEN); (void) memset(auth.dat, 0, MAX_KTXT_LEN);
r = sizeof(local); slen = sizeof(local);
memset(&local, 0, sizeof(local)); memset(&local, 0, sizeof(local));
if (getsockname(packet_get_connection_in(), if (getsockname(packet_get_connection_in(),
(struct sockaddr *) & local, &r) < 0) (struct sockaddr *) & local, &slen) < 0)
debug("getsockname failed: %s", strerror(errno)); debug("getsockname failed: %s", strerror(errno));
r = sizeof(foreign); slen = sizeof(foreign);
memset(&foreign, 0, sizeof(foreign)); memset(&foreign, 0, sizeof(foreign));
if (getpeername(packet_get_connection_in(), if (getpeername(packet_get_connection_in(),
(struct sockaddr *) & foreign, &r) < 0) { (struct sockaddr *) & foreign, &slen) < 0) {
debug("getpeername failed: %s", strerror(errno)); debug("getpeername failed: %s", strerror(errno));
fatal_cleanup(); fatal_cleanup();
} }
@ -751,7 +752,7 @@ send_kerberos_tgt()
CREDENTIALS *creds; CREDENTIALS *creds;
char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
int r, type, plen; int r, type, plen;
unsigned char buffer[8192]; char buffer[8192];
struct stat st; struct stat st;
/* Don't do anything if we don't have any tickets. */ /* Don't do anything if we don't have any tickets. */
@ -772,11 +773,11 @@ send_kerberos_tgt()
debug("Kerberos V4 ticket expired: %s", TKT_FILE); debug("Kerberos V4 ticket expired: %s", TKT_FILE);
return 0; return 0;
} }
creds_to_radix(creds, buffer); creds_to_radix(creds, (unsigned char *)buffer);
xfree(creds); xfree(creds);
packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
packet_put_string((char *) buffer, strlen(buffer)); packet_put_string(buffer, strlen(buffer));
packet_send(); packet_send();
packet_write_wait(); packet_write_wait();
@ -798,7 +799,7 @@ send_afs_tokens(void)
struct ClearToken ct; struct ClearToken ct;
int i, type, len, plen; int i, type, len, plen;
char buf[2048], *p, *server_cell; char buf[2048], *p, *server_cell;
unsigned char buffer[8192]; char buffer[8192];
/* Move over ktc_GetToken, here's something leaner. */ /* Move over ktc_GetToken, here's something leaner. */
for (i = 0; i < 100; i++) { /* just in case */ for (i = 0; i < 100; i++) { /* just in case */
@ -840,10 +841,10 @@ send_afs_tokens(void)
creds.pinst[0] = '\0'; creds.pinst[0] = '\0';
/* Encode token, ship it off. */ /* Encode token, ship it off. */
if (!creds_to_radix(&creds, buffer)) if (!creds_to_radix(&creds, (unsigned char*) buffer))
break; break;
packet_start(SSH_CMSG_HAVE_AFS_TOKEN); packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
packet_put_string((char *) buffer, strlen(buffer)); packet_put_string(buffer, strlen(buffer));
packet_send(); packet_send();
packet_write_wait(); packet_write_wait();
@ -867,7 +868,9 @@ send_afs_tokens(void)
int int
try_skey_authentication() try_skey_authentication()
{ {
int type, i, payload_len; int type, i;
int payload_len;
unsigned int clen;
char *challenge, *response; char *challenge, *response;
debug("Doing skey authentication."); debug("Doing skey authentication.");
@ -887,7 +890,8 @@ try_skey_authentication()
debug("No challenge for skey authentication."); debug("No challenge for skey authentication.");
return 0; return 0;
} }
challenge = packet_get_string(&payload_len); challenge = packet_get_string(&clen);
packet_integrity_check(payload_len, (4 + clen), type);
if (options.cipher == SSH_CIPHER_NONE) if (options.cipher == SSH_CIPHER_NONE)
log("WARNING: Encryption is disabled! " log("WARNING: Encryption is disabled! "
"Reponse will be transmitted in clear text."); "Reponse will be transmitted in clear text.");

4
sshd.8
View File

@ -9,7 +9,7 @@
.\" .\"
.\" Created: Sat Apr 22 21:55:14 1995 ylo .\" Created: Sat Apr 22 21:55:14 1995 ylo
.\" .\"
.\" $Id: sshd.8,v 1.13 2000/03/09 10:27:53 damien Exp $ .\" $Id: sshd.8,v 1.14 2000/03/17 12:40:18 damien Exp $
.\" .\"
.Dd September 25, 1999 .Dd September 25, 1999
.Dt SSHD 8 .Dt SSHD 8
@ -147,7 +147,7 @@ is normally not run
from inetd because it needs to generate the server key before it can from inetd because it needs to generate the server key before it can
respond to the client, and this may take tens of seconds. Clients respond to the client, and this may take tens of seconds. Clients
would have to wait too long if the key was regenerated every time. would have to wait too long if the key was regenerated every time.
However, with small key sizes (e.g. 512) using However, with small key sizes (e.g., 512) using
.Nm .Nm
from inetd may from inetd may
be feasible. be feasible.

18
sshd.c
View File

@ -11,7 +11,7 @@
*/ */
#include "includes.h" #include "includes.h"
RCSID("$OpenBSD: sshd.c,v 1.91 2000/03/09 19:31:47 markus Exp $"); RCSID("$OpenBSD: sshd.c,v 1.92 2000/03/16 20:56:15 markus Exp $");
#include "xmalloc.h" #include "xmalloc.h"
#include "rsa.h" #include "rsa.h"
@ -1202,7 +1202,8 @@ void
do_authentication() do_authentication()
{ {
struct passwd *pw, pwcopy; struct passwd *pw, pwcopy;
int plen, ulen; int plen;
unsigned int ulen;
char *user; char *user;
/* Get the name of the user that we wish to log in as. */ /* Get the name of the user that we wish to log in as. */
@ -1304,7 +1305,9 @@ do_authloop(struct passwd * pw)
BIGNUM *n; BIGNUM *n;
char *client_user = NULL, *password = NULL; char *client_user = NULL, *password = NULL;
char user[1024]; char user[1024];
int plen, dlen, nlen, ulen, elen; unsigned int dlen;
int plen, nlen, elen;
unsigned int ulen;
int type = 0; int type = 0;
void (*authlog) (const char *fmt,...) = verbose; void (*authlog) (const char *fmt,...) = verbose;
@ -1608,7 +1611,7 @@ do_fake_authloop(char *user)
(void)packet_read(&plen); (void)packet_read(&plen);
#else /* SKEY */ #else /* SKEY */
int type = packet_read(&plen); int type = packet_read(&plen);
int dlen; unsigned int dlen;
char *password, *skeyinfo; char *password, *skeyinfo;
/* Try to send a fake s/key challenge. */ /* Try to send a fake s/key challenge. */
if (options.skey_authentication == 1 && if (options.skey_authentication == 1 &&
@ -1697,6 +1700,8 @@ do_authenticated(struct passwd * pw)
int row, col, xpixel, ypixel, screen; int row, col, xpixel, ypixel, screen;
char ttyname[64]; char ttyname[64];
char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL; char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL;
int plen;
unsigned int dlen;
int n_bytes; int n_bytes;
/* /*
@ -1720,7 +1725,6 @@ do_authenticated(struct passwd * pw)
* or a command. * or a command.
*/ */
while (1) { while (1) {
int plen, dlen;
/* Get a packet from the client. */ /* Get a packet from the client. */
type = packet_read(&plen); type = packet_read(&plen);
@ -1799,7 +1803,7 @@ do_authenticated(struct passwd * pw)
if (display) if (display)
packet_disconnect("Protocol error: X11 display already set."); packet_disconnect("Protocol error: X11 display already set.");
{ {
int proto_len, data_len; unsigned int proto_len, data_len;
proto = packet_get_string(&proto_len); proto = packet_get_string(&proto_len);
data = packet_get_string(&data_len); data = packet_get_string(&data_len);
packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type); packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type);
@ -1881,7 +1885,7 @@ do_authenticated(struct passwd * pw)
goto do_forced_command; goto do_forced_command;
/* Get command from the packet. */ /* Get command from the packet. */
{ {
int dlen; unsigned int dlen;
command = packet_get_string(&dlen); command = packet_get_string(&dlen);
debug("Executing command '%.500s'", command); debug("Executing command '%.500s'", command);
packet_integrity_check(plen, 4 + dlen, type); packet_integrity_check(plen, 4 + dlen, type);