diff --git a/ChangeLog b/ChangeLog
index a55a3b3d7..9b0b3e2af 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 20050215
  - (dtucker) [config.sh.in] Collect oslevel -r too.
+ - (dtucker) [README.platform auth.c configure.ac loginrec.c
+   openbsd-compat/port-aix.c openbsd-compat/port-aix.h] Bug #835: enable IPv6
+   on AIX where possible (see README.platform for details) and work around
+   a misfeature of AIX's getnameinfo.  ok djm@
 
 20050211
  - (dtucker) [configure.ac] Tidy up configure --help output.
@@ -2126,4 +2130,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.3651 2005/02/15 10:26:32 dtucker Exp $
+$Id: ChangeLog,v 1.3652 2005/02/15 10:45:57 dtucker Exp $
diff --git a/README.platform b/README.platform
index 880b83c63..136304a8e 100644
--- a/README.platform
+++ b/README.platform
@@ -13,6 +13,15 @@ Accounts in this state must have their passwords reset manually by the
 administrator.  As a precaution, it is recommended that the administrative
 passwords be reset before upgrading from OpenSSH <3.8.
 
+As of OpenSSH 4.0, configure will attempt to detect if your version
+and maintenance level of AIX has a working getaddrinfo, and will use it
+if found.  This will enable IPv6 support.  If for some reason configure
+gets it wrong, or if you want to build binaries to work on earlier MLs
+than the build host then you can add "-DBROKEN_GETADDRINFO" to CFLAGS
+to force the previous IPv4-only behaviour.
+
+IPv6 known to work: 5.2ML2 5.2ML5
+IPv6 known broken: 4.3.3ML11 5.1ML4
 
 Cygwin
 ------
@@ -27,4 +36,4 @@ Currently, sshd does not support BSM auditting.  This can show up as errors
 when editting cron entries via crontab.  See.
 http://bugzilla.mindrot.org/show_bug.cgi?id=125
 
-$Id: README.platform,v 1.2 2004/04/23 08:57:13 dtucker Exp $
+$Id: README.platform,v 1.3 2005/02/15 10:45:57 dtucker Exp $
diff --git a/auth.c b/auth.c
index e6dcab209..256807683 100644
--- a/auth.c
+++ b/auth.c
@@ -209,7 +209,7 @@ allowed_user(struct passwd * pw)
 	}
 
 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
-	if (!sys_auth_allowed_user(pw))
+	if (!sys_auth_allowed_user(pw, &loginmsg))
 		return 0;
 #endif
 
diff --git a/configure.ac b/configure.ac
index 2df8a5e87..b27f0cf70 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-# $Id: configure.ac,v 1.241 2005/02/11 05:11:49 dtucker Exp $
+# $Id: configure.ac,v 1.242 2005/02/15 10:45:57 dtucker Exp $
 #
 # Copyright (c) 1999-2004 Damien Miller
 #
@@ -135,7 +135,7 @@ case "$host" in
 		[#include <usersec.h>]
 	)
 	AC_CHECK_FUNCS(setauthdb)
-	AC_DEFINE(BROKEN_GETADDRINFO)
+	check_for_aix_broken_getaddrinfo=1
 	AC_DEFINE(BROKEN_REALPATH)
 	AC_DEFINE(SETEUID_BREAKS_SETUID)
 	AC_DEFINE(BROKEN_SETREUID)
@@ -1146,6 +1146,64 @@ main(void)
 	)
 fi
 
+if test "x$ac_cv_func_getaddrinfo" = "xyes" -a "x$check_for_aix_broken_getaddrinfo" = "x1"; then
+	AC_MSG_CHECKING(if getaddrinfo seems to work)
+	AC_TRY_RUN(
+		[
+#include <stdio.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <errno.h>
+#include <netinet/in.h>
+
+#define TEST_PORT "2222"
+
+int
+main(void)
+{
+	int err, sock;
+	struct addrinfo *gai_ai, *ai, hints;
+	char ntop[NI_MAXHOST], strport[NI_MAXSERV], *name = NULL;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = PF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_PASSIVE;
+
+	err = getaddrinfo(name, TEST_PORT, &hints, &gai_ai);
+	if (err != 0) {
+		fprintf(stderr, "getaddrinfo failed (%s)", gai_strerror(err));
+		exit(1);
+	}
+
+	for (ai = gai_ai; ai != NULL; ai = ai->ai_next) {
+		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			continue;
+
+		err = getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop,
+		    sizeof(ntop), strport, sizeof(strport),
+		    NI_NUMERICHOST|NI_NUMERICSERV);
+
+		if (ai->ai_family == AF_INET && err != 0) {
+			perror("getnameinfo");
+			exit(2);
+		}
+	}
+	exit(0);
+}
+		],
+		[
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(AIX_GETNAMEINFO_HACK, [],
+[Define if you have a getaddrinfo that fails for the all-zeros IPv6 address])
+		],
+		[
+			AC_MSG_RESULT(no)
+			AC_DEFINE(BROKEN_GETADDRINFO)
+		]
+	)
+fi
+
 if test "x$check_for_conflicting_getspnam" = "x1"; then
 	AC_MSG_CHECKING(for conflicting getspnam in shadow.h)
 	AC_COMPILE_IFELSE(
diff --git a/loginrec.c b/loginrec.c
index c033582ad..8f5061cdc 100644
--- a/loginrec.c
+++ b/loginrec.c
@@ -164,7 +164,7 @@
 # include <libutil.h>
 #endif
 
-RCSID("$Id: loginrec.c,v 1.65 2005/02/08 10:52:48 dtucker Exp $");
+RCSID("$Id: loginrec.c,v 1.66 2005/02/15 10:45:57 dtucker Exp $");
 
 /**
  ** prototypes for helper functions in this file
@@ -192,6 +192,8 @@ int lastlog_get_entry(struct logininfo *li);
 int wtmp_get_entry(struct logininfo *li);
 int wtmpx_get_entry(struct logininfo *li);
 
+extern Buffer loginmsg;
+
 /* pick the shortest string */
 #define MIN_SIZEOF(s1,s2) (sizeof(s1) < sizeof(s2) ? sizeof(s1) : sizeof(s2))
 
@@ -441,7 +443,7 @@ login_write(struct logininfo *li)
 #endif
 #ifdef CUSTOM_SYS_AUTH_RECORD_LOGIN
 	if (li->type == LTYPE_LOGIN && 
-	   !sys_auth_record_login(li->username,li->hostname,li->line))
+	   !sys_auth_record_login(li->username,li->hostname,li->line, &loginmsg))
 		logit("Writing login record failed for %s", li->username);
 #endif
 #ifdef SSH_AUDIT_EVENTS
diff --git a/openbsd-compat/port-aix.c b/openbsd-compat/port-aix.c
index b16988543..8ab862f98 100644
--- a/openbsd-compat/port-aix.c
+++ b/openbsd-compat/port-aix.c
@@ -34,14 +34,13 @@
 #ifdef _AIX
 
 #include <uinfo.h>
+#include <sys/socket.h>
 #include "port-aix.h"
 
 /* These should be in the system headers but are not. */
 int usrinfo(int, char *, int);
 int setauthdb(const char *, char *);
 
-extern Buffer loginmsg;
-
 # ifdef HAVE_SETAUTHDB
 static char old_registry[REGISTRY_SIZE] = "";
 # endif
@@ -156,7 +155,7 @@ aix_valid_authentications(const char *user)
  * returns 0.
  */
 int
-sys_auth_passwd(Authctxt *ctxt, const char *password)
+sys_auth_passwd(Authctxt *ctxt, const char *password, Buffer *loginmsg)
 {
 	char *authmsg = NULL, *msg, *name = ctxt->pw->pw_name;
 	int authsuccess = 0, expired, reenter, result;
@@ -186,7 +185,7 @@ sys_auth_passwd(Authctxt *ctxt, const char *password)
 		 */
 		expired = passwdexpired(name, &msg);
 		if (msg && *msg) {
-			buffer_append(&loginmsg, msg, strlen(msg));
+			buffer_append(loginmsg, msg, strlen(msg));
 			aix_remove_embedded_newlines(msg);
 		}
 		debug3("AIX/passwdexpired returned %d msg %.100s", expired, msg);
@@ -219,7 +218,7 @@ sys_auth_passwd(Authctxt *ctxt, const char *password)
  * Returns 1 if login is allowed, 0 if not allowed.
  */
 int
-sys_auth_allowed_user(struct passwd *pw)
+sys_auth_allowed_user(struct passwd *pw, Buffer *loginmsg)
 {
 	char *msg = NULL;
 	int result, permitted = 0;
@@ -246,7 +245,7 @@ sys_auth_allowed_user(struct passwd *pw)
 	if (result == -1 && errno == EPERM && stat(_PATH_NOLOGIN, &st) == 0)
 		permitted = 1;
 	else if (msg != NULL)
-		buffer_append(&loginmsg, msg, strlen(msg));
+		buffer_append(loginmsg, msg, strlen(msg));
 	if (msg == NULL)
 		msg = xstrdup("(none)");
 	aix_remove_embedded_newlines(msg);
@@ -259,7 +258,8 @@ sys_auth_allowed_user(struct passwd *pw)
 }
 
 int
-sys_auth_record_login(const char *user, const char *host, const char *ttynm)
+sys_auth_record_login(const char *user, const char *host, const char *ttynm,
+    Buffer *loginmsg)
 {
 	char *msg;
 	int success = 0;
@@ -269,7 +269,7 @@ sys_auth_record_login(const char *user, const char *host, const char *ttynm)
 		success = 1;
 		if (msg != NULL) {
 			debug("AIX/loginsuccess: msg %s", msg);
-			buffer_append(&loginmsg, msg, strlen(msg));
+			buffer_append(loginmsg, msg, strlen(msg));
 			xfree(msg);
 		}
 	}
@@ -349,4 +349,33 @@ aix_restoreauthdb(void)
 
 # endif /* WITH_AIXAUTHENTICATE */
 
+# if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_ADDRINFO)
+# undef getnameinfo
+/*
+ * For some reason, AIX's getnameinfo will refuse to resolve the all-zeros
+ * IPv6 address into its textual representation ("::"), so we wrap it
+ * with a function that will.
+ */
+int
+sshaix_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
+    size_t hostlen, char *serv, size_t servlen, int flags)
+{
+	struct sockaddr_in6 *sa6;
+	u_int32_t *a6;
+
+	if (flags & (NI_NUMERICHOST|NI_NUMERICSERV) &&
+	    sa->sa_family == AF_INET6) {
+		sa6 = (struct sockaddr_in6 *)sa;
+		a6 = sa6->sin6_addr.u6_addr.u6_addr32;
+
+		if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
+			strlcpy(host, "::", hostlen);
+			snprintf(serv, servlen, "%d", sa6->sin6_port);
+			return 0;
+		}
+	}
+	return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
+}
+# endif /* AIX_GETNAMEINFO_HACK */
+
 #endif /* _AIX */
diff --git a/openbsd-compat/port-aix.h b/openbsd-compat/port-aix.h
index 751139004..cc7c43cda 100644
--- a/openbsd-compat/port-aix.h
+++ b/openbsd-compat/port-aix.h
@@ -1,4 +1,4 @@
-/* $Id: port-aix.h,v 1.22 2005/02/02 06:10:11 dtucker Exp $ */
+/* $Id: port-aix.h,v 1.23 2005/02/15 10:45:58 dtucker Exp $ */
 
 /*
  *
@@ -27,6 +27,10 @@
 
 #ifdef _AIX
 
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+
 #ifdef WITH_AIXAUTHENTICATE
 # include <login.h>
 # include <userpw.h>
@@ -36,6 +40,8 @@
 # include <usersec.h>
 #endif
 
+#include "buffer.h"
+
 /* Some versions define r_type in the above headers, which causes a conflict */
 #ifdef r_type
 # undef r_type
@@ -64,13 +70,23 @@ void aix_usrinfo(struct passwd *);
 #ifdef WITH_AIXAUTHENTICATE
 # define CUSTOM_SYS_AUTH_PASSWD 1
 # define CUSTOM_SYS_AUTH_ALLOWED_USER 1
-int sys_auth_allowed_user(struct passwd *);
+int sys_auth_allowed_user(struct passwd *, Buffer *);
 # define CUSTOM_SYS_AUTH_RECORD_LOGIN 1
-int sys_auth_record_login(const char *, const char *, const char *);
+int sys_auth_record_login(const char *, const char *, const char *, Buffer *);
 # define CUSTOM_FAILED_LOGIN 1
 #endif
 
 void aix_setauthdb(const char *);
 void aix_restoreauthdb(void);
 void aix_remove_embedded_newlines(char *);
+
+#if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_GETADDRINFO)
+# ifdef getnameinfo
+#  undef getnameinfo
+# endif
+int sshaix_getnameinfo(const struct sockaddr *, size_t, char *, size_t,
+    char *, size_t, int);
+# define getnameinfo(a,b,c,d,e,f,g) (sshaix_getnameinfo(a,b,c,d,e,f,g))
+#endif
+
 #endif /* _AIX */