3 files changed, 20 insertions, 8 deletions

diff --git a/clientloop.c b/clientloop.c
index 626b29a5a..a13d06ddf 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -324,12 +324,17 @@ client_global_request_reply(int type, u_int32_t seq, void *ctxt)
 static void
 server_alive_check(void)
 {
-        if (++server_alive_timeouts > options.server_alive_count_max)
-                packet_disconnect("Timeout, server not responding.");
-        packet_start(SSH2_MSG_GLOBAL_REQUEST);
-        packet_put_cstring("keepalive@openssh.com");
-        packet_put_char(1);     /* boolean: want reply */
-        packet_send();
+        if (compat20) {
+                if (++server_alive_timeouts > options.server_alive_count_max)
+                        packet_disconnect("Timeout, server not responding.");
+                packet_start(SSH2_MSG_GLOBAL_REQUEST);
+                packet_put_cstring("keepalive@openssh.com");
+                packet_put_char(1);     /* boolean: want reply */
+                packet_send();
+        } else {
+                packet_send_ignore(0);
+                packet_send();
+        }
 }
 
 /*
@@ -388,7 +393,7 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
          * event pending.
          */
 
-        if (options.server_alive_interval == 0 || !compat20)
+        if (options.server_alive_interval == 0)
                 tvp = NULL;
         else {  
                 tv.tv_sec = options.server_alive_interval;
diff --git a/debian/changelog b/debian/changelog
index 5a05d0f3e..2bb0f227a 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -19,6 +19,8 @@ openssh (1:3.8p1-1) UNRELEASED; urgency=low
   * ServerAliveInterval implemented upstream, so ProtocolKeepAlives is now a
     compatibility alias. The semantics differ slightly, though; see
     ssh_config(5) for details.
+  * Implement SSH1 support for ServerAliveInterval using SSH_MSG_IGNORE. As
+    documented in ssh_config(5), it's not as good as the SSH2 version.
   * Remove -fno-builtin-log, -DHAVE_MMAP_ANON_SHARED, and
     -D__FILE_OFFSET_BITS=64 compiler options, which are no longer necessary.
   * Update config.guess and config.sub from autotools-dev 20040105.1.
diff --git a/ssh_config.5 b/ssh_config.5
index 25485f3da..72ad6d512 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -570,7 +570,8 @@ is 0, indicating that these messages will not be sent to the server,
 or 300 if the
 .Cm BatchMode
 option is set.
-This option applies to protocol version 2 only.
+.Cm ProtocolKeepAlives
+is a Debian-specific compatibility alias for this option.
 .It Cm ServerAliveCountMax
 Sets the number of server alive messages (see above) which may be
 sent without
@@ -598,6 +599,10 @@ If, for example,
 .Cm ServerAliveCountMax
 is left at the default, if the server becomes unresponsive ssh
 will disconnect after approximately 45 seconds.
+This option works when using protocol version 2 only; in protocol version
+1 there is no mechanism to request a response from the server to the
+server alive messages, so disconnection is the responsibility of the TCP
+stack.
 .It Cm SetupTimeOut
 Normally,
 .Nm ssh