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27f6cfa7b0
* Add an environement variable to control stdio mode stdio descriptors (stdin, stdout and stderr) can be operated in various modes by win32compat code. The behavior is set very early in fd_table_initialize() by setting pio->type. In https://github.com/PowerShell/Win32-OpenSSH/issues/1427 it was chosen to set pio->type to NONSOCK_SYNC_FD to resolve an I/O hang problem. Unfortunately this introduce problems for other ssh usage. sshfs-wiun uses ssh and has at leas 6 open issues for the same problem introduced by this NONSOCK_SYNC_FD change: https://github.com/winfsp/sshfs-win/issues?q=is%3Aissue+cb+%3A87 The sshfs-win workaround it to use an older ssh.exe from cygwin, which is bundled with sshfs-win. This program is unable to use ssh-agent, which is quite frustrating. And if PATH is not set to use it, sshfs-win cannot work. This change introduce an OPENSSH_STDIO_MODE environment variable that can be set to the following values: unknown, sock, nonsock, nonsock_sync. It cause pio->type to be set to UNKNOWN_FD, SOCK_FD, NONSOCK_FD, and NONSOCK_SYNC_FD respecitively. The default behavior when the variable is not set is unchanged (which means NONSOCK_SYNC_FD). Setting OPENSSH_STDIO_MODE="nonsock" lets sshfs-win work again with openssh-portable ssh.exe. ssh-agent can be used, and this is good. * Leave out UNKNOWN_FD as the possible rtpes for stdio descriptors An assert(pio->type != UNKNOWN_FD) in fd_table_set() causes that case to fail early anyway.
Portable OpenSSH
OpenSSH is a complete implementation of the SSH protocol (version 2) for secure remote login, command execution and file transfer. It includes a client ssh and server sshd, file transfer utilities scp and sftp as well as tools for key generation (ssh-keygen), run-time key storage (ssh-agent) and a number of supporting programs.
This is a port of OpenBSD's OpenSSH to most Unix-like operating systems, including Linux, OS X and Cygwin. Portable OpenSSH polyfills OpenBSD APIs that are not available elsewhere, adds sshd sandboxing for more operating systems and includes support for OS-native authentication and auditing (e.g. using PAM).
Documentation
The official documentation for OpenSSH are the man pages for each tool:
Stable Releases
Stable release tarballs are available from a number of download mirrors. We recommend the use of a stable release for most users. Please read the release notes for details of recent changes and potential incompatibilities.
Building Portable OpenSSH
Dependencies
Portable OpenSSH is built using autoconf and make. It requires a working C compiler, standard library and headers.
libcrypto from either LibreSSL or OpenSSL may also be used. OpenSSH may be built without either of these, but the resulting binaries will have only a subset of the cryptographic algorithms normally available.
zlib is optional; without it transport compression is not supported.
FIDO security token support needs libfido2 and its dependencies and will be enabled automatically if they are found.
In addition, certain platforms and build-time options may require additional dependencies; see README.platform for details about your platform.
Building a release
Releases include a pre-built copy of the configure script and may be built using:
tar zxvf openssh-X.YpZ.tar.gz
cd openssh
./configure # [options]
make && make tests
See the Build-time Customisation section below for configure options. If you plan on installing OpenSSH to your system, then you will usually want to specify destination paths.
Building from git
If building from git, you'll need autoconf installed to build the configure script. The following commands will check out and build portable OpenSSH from git:
git clone https://github.com/openssh/openssh-portable # or https://anongit.mindrot.org/openssh.git
cd openssh-portable
autoreconf
./configure
make && make tests
Build-time Customisation
There are many build-time customisation options available. All Autoconf destination path flags (e.g. --prefix) are supported (and are usually required if you want to install OpenSSH).
For a full list of available flags, run ./configure --help but a few of the more frequently-used ones are described below. Some of these flags will require additional libraries and/or headers be installed.
| Flag | Meaning |
|---|---|
--with-pam |
Enable PAM support. OpenPAM, Linux PAM and Solaris PAM are supported. |
--with-libedit |
Enable libedit support for sftp. |
--with-kerberos5 |
Enable Kerberos/GSSAPI support. Both Heimdal and MIT Kerberos implementations are supported. |
--with-selinux |
Enable SELinux support. |
Development
Portable OpenSSH development is discussed on the openssh-unix-dev mailing list (archive mirror). Bugs and feature requests are tracked on our Bugzilla.
Reporting bugs
Non-security bugs may be reported to the developers via Bugzilla or via the mailing list above. Security bugs should be reported to openssh@openssh.com.