Description: Partial server keep-alive implementation for SSH1 Author: Colin Watson Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1712 Last-Update: 2013-09-14 Index: b/clientloop.c =================================================================== --- a/clientloop.c +++ b/clientloop.c @@ -563,16 +563,21 @@ static void server_alive_check(void) { - if (packet_inc_alive_timeouts() > options.server_alive_count_max) { - logit("Timeout, server %s not responding.", host); - cleanup_exit(255); + if (compat20) { + if (packet_inc_alive_timeouts() > options.server_alive_count_max) { + logit("Timeout, server %s not responding.", host); + cleanup_exit(255); + } + packet_start(SSH2_MSG_GLOBAL_REQUEST); + packet_put_cstring("keepalive@openssh.com"); + packet_put_char(1); /* boolean: want reply */ + packet_send(); + /* Insert an empty placeholder to maintain ordering */ + client_register_global_confirm(NULL, NULL); + } else { + packet_send_ignore(0); + packet_send(); } - packet_start(SSH2_MSG_GLOBAL_REQUEST); - packet_put_cstring("keepalive@openssh.com"); - packet_put_char(1); /* boolean: want reply */ - packet_send(); - /* Insert an empty placeholder to maintain ordering */ - client_register_global_confirm(NULL, NULL); } /* @@ -634,7 +639,7 @@ */ timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */ - if (options.server_alive_interval > 0 && compat20) { + if (options.server_alive_interval > 0) { timeout_secs = options.server_alive_interval; server_alive_time = now + options.server_alive_interval; } Index: b/ssh_config.5 =================================================================== --- a/ssh_config.5 +++ b/ssh_config.5 @@ -1130,7 +1130,10 @@ .Cm ServerAliveCountMax is left at the default, if the server becomes unresponsive, ssh will disconnect after approximately 45 seconds. -This option applies to protocol version 2 only. +This option applies to 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 ServerAliveInterval Sets a timeout interval in seconds after which if no data has been received from the server,