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From fccfbc7104e40148f6695f958f2f1b9e15011a38 Mon Sep 17 00:00:00 2001
From: Richard Kettlewell <rjk@greenend.org.uk>
Date: Sun, 9 Feb 2014 16:09:52 +0000
Subject: Various keepalive extensions
Add compatibility aliases for ProtocolKeepAlives and SetupTimeOut, supported
in previous versions of Debian's OpenSSH package but since superseded by
ServerAliveInterval. (We're probably stuck with this bit for
compatibility.)
In batch mode, default ServerAliveInterval to five minutes.
Adjust documentation to match and to give some more advice on use of
keepalives.
Author: Ian Jackson <ian@chiark.greenend.org.uk>
Author: Matthew Vernon <matthew@debian.org>
Author: Colin Watson <cjwatson@debian.org>
Last-Update: 2017-05-03
Patch-Name: keepalive-extensions.patch
---
readconf.c | 14 ++++++++++++--
ssh_config.5 | 21 +++++++++++++++++++--
2 files changed, 31 insertions(+), 4 deletions(-)
diff --git a/readconf.c b/readconf.c
index 40900c5c4..09c0339b0 100644
--- a/readconf.c
+++ b/readconf.c
@@ -171,6 +171,7 @@ typedef enum {
oStreamLocalBindMask, oStreamLocalBindUnlink, oRevokedHostKeys,
oFingerprintHash, oUpdateHostkeys, oHostbasedKeyTypes,
oPubkeyAcceptedKeyTypes, oProxyJump,
+ oProtocolKeepAlives, oSetupTimeOut,
oIgnoredUnknownOption, oDeprecated, oUnsupported
} OpCodes;
@@ -309,6 +310,8 @@ static struct {
{ "pubkeyacceptedkeytypes", oPubkeyAcceptedKeyTypes },
{ "ignoreunknown", oIgnoreUnknown },
{ "proxyjump", oProxyJump },
+ { "protocolkeepalives", oProtocolKeepAlives },
+ { "setuptimeout", oSetupTimeOut },
{ NULL, oBadOption }
};
@@ -1385,6 +1388,8 @@ parse_keytypes:
goto parse_flag;
case oServerAliveInterval:
+ case oProtocolKeepAlives: /* Debian-specific compatibility alias */
+ case oSetupTimeOut: /* Debian-specific compatibility alias */
intptr = &options->server_alive_interval;
goto parse_time;
@@ -2027,8 +2032,13 @@ fill_default_options(Options * options)
options->rekey_interval = 0;
if (options->verify_host_key_dns == -1)
options->verify_host_key_dns = 0;
- if (options->server_alive_interval == -1)
- options->server_alive_interval = 0;
+ if (options->server_alive_interval == -1) {
+ /* in batch mode, default is 5mins */
+ if (options->batch_mode == 1)
+ options->server_alive_interval = 300;
+ else
+ options->server_alive_interval = 0;
+ }
if (options->server_alive_count_max == -1)
options->server_alive_count_max = 3;
if (options->control_master == -1)
diff --git a/ssh_config.5 b/ssh_config.5
index 532745b2f..0b9fda02f 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -250,8 +250,12 @@ Valid arguments are
If set to
.Cm yes ,
passphrase/password querying will be disabled.
+In addition, the
+.Cm ServerAliveInterval
+option will be set to 300 seconds by default (Debian-specific).
This option is useful in scripts and other batch jobs where no user
-is present to supply the password.
+is present to supply the password,
+and where it is desirable to detect a broken network swiftly.
The argument must be
.Cm yes
or
@@ -1477,7 +1481,14 @@ from the server,
will send a message through the encrypted
channel to request a response from the server.
The default
-is 0, indicating that these messages will not be sent to the server.
+is 0, indicating that these messages will not be sent to the server,
+or 300 if the
+.Cm BatchMode
+option is set (Debian-specific).
+.Cm ProtocolKeepAlives
+and
+.Cm SetupTimeOut
+are Debian-specific compatibility aliases for this option.
.It Cm StreamLocalBindMask
Sets the octal file creation mode mask
.Pq umask
@@ -1536,6 +1547,12 @@ Specifies whether the system should send TCP keepalive messages to the
other side.
If they are sent, death of the connection or crash of one
of the machines will be properly noticed.
+This option only uses TCP keepalives (as opposed to using ssh level
+keepalives), so takes a long time to notice when the connection dies.
+As such, you probably want
+the
+.Cm ServerAliveInterval
+option as well.
However, this means that
connections will die if the route is down temporarily, and some people
find it annoying.
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