1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
From affb41e3cf23b79a3d165ae0d97689a46a965b6f 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in previous versions of Debian's OpenSSH package but since superseded by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: 2013-09-14
Patch-Name: keepalive-extensions.patch
---
readconf.c | 14 ++++++++++++--
ssh_config.5 | 21 +++++++++++++++++++--
sshd_config.5 | 3 +++
3 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/readconf.c b/readconf.c
index 22e5a3a..2dcbf31 100644
--- a/readconf.c
+++ b/readconf.c
@@ -141,6 +141,7 @@ typedef enum {
oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand,
oVisualHostKey, oUseRoaming, oZeroKnowledgePasswordAuthentication,
oKexAlgorithms, oIPQoS, oRequestTTY, oIgnoreUnknown,
+ oProtocolKeepAlives, oSetupTimeOut,
oIgnoredUnknownOption, oDeprecated, oUnsupported
} OpCodes;
@@ -263,6 +264,8 @@ static struct {
{ "ipqos", oIPQoS },
{ "requesttty", oRequestTTY },
{ "ignoreunknown", oIgnoreUnknown },
+ { "protocolkeepalives", oProtocolKeepAlives },
+ { "setuptimeout", oSetupTimeOut },
{ NULL, oBadOption }
};
@@ -939,6 +942,8 @@ parse_int:
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;
@@ -1404,8 +1409,13 @@ 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 89b25cd..135d833 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -136,8 +136,12 @@ Valid arguments are
If set to
.Dq yes ,
passphrase/password querying will be disabled.
+In addition, the
+.Cm ServerAliveInterval
+option will be set to 300 seconds by default.
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
.Dq yes
or
@@ -1141,8 +1145,15 @@ 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.
This option applies to protocol version 2 only.
+.Cm ProtocolKeepAlives
+and
+.Cm SetupTimeOut
+are Debian-specific compatibility aliases for this option.
.It Cm StrictHostKeyChecking
If this flag is set to
.Dq yes ,
@@ -1181,6 +1192,12 @@ 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.
diff --git a/sshd_config.5 b/sshd_config.5
index 18ec81f..510cc7c 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -1161,6 +1161,9 @@ This avoids infinitely hanging sessions.
.Pp
To disable TCP keepalive messages, the value should be set to
.Dq no .
+.Pp
+This option was formerly called
+.Cm KeepAlive .
.It Cm TrustedUserCAKeys
Specifies a file containing public keys of certificate authorities that are
trusted to sign user certificates for authentication.
|
