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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
From a466a627b806905df9c7583af7edcf39e9481201 Mon Sep 17 00:00:00 2001
From: Colin Watson <cjwatson@debian.org>
Date: Sun, 9 Feb 2014 16:10:18 +0000
Subject: Various Debian-specific configuration changes
ssh: Enable ForwardX11Trusted, returning to earlier semantics which cause
fewer problems with existing setups (http://bugs.debian.org/237021).
ssh: Set 'SendEnv LANG LC_*' by default (http://bugs.debian.org/264024).
ssh: Enable HashKnownHosts by default to try to limit the spread of ssh
worms.
ssh: Enable GSSAPIAuthentication and disable GSSAPIDelegateCredentials by
default.
Document all of this, along with several sshd defaults set in
debian/openssh-server.postinst.
Author: Russ Allbery <rra@debian.org>
Forwarded: not-needed
Last-Update: 2015-12-07
Patch-Name: debian-config.patch
---
readconf.c | 2 +-
ssh.1 | 21 +++++++++++++++++++++
ssh_config | 7 ++++++-
ssh_config.5 | 19 ++++++++++++++++++-
sshd_config | 2 +-
sshd_config.5 | 25 +++++++++++++++++++++++++
6 files changed, 72 insertions(+), 4 deletions(-)
diff --git a/readconf.c b/readconf.c
index c0ba5a7..e4e1cba 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1749,7 +1749,7 @@ fill_default_options(Options * options)
if (options->forward_x11 == -1)
options->forward_x11 = 0;
if (options->forward_x11_trusted == -1)
- options->forward_x11_trusted = 0;
+ options->forward_x11_trusted = 1;
if (options->forward_x11_timeout == -1)
options->forward_x11_timeout = 1200;
if (options->exit_on_forward_failure == -1)
diff --git a/ssh.1 b/ssh.1
index 05b7f10..649d6c3 100644
--- a/ssh.1
+++ b/ssh.1
@@ -755,6 +755,16 @@ directive in
.Xr ssh_config 5
for more information.
.Pp
+(Debian-specific: X11 forwarding is not subjected to X11 SECURITY extension
+restrictions by default, because too many programs currently crash in this
+mode.
+Set the
+.Cm ForwardX11Trusted
+option to
+.Dq no
+to restore the upstream behaviour.
+This may change in future depending on client-side improvements.)
+.Pp
.It Fl x
Disables X11 forwarding.
.Pp
@@ -763,6 +773,17 @@ Enables trusted X11 forwarding.
Trusted X11 forwardings are not subjected to the X11 SECURITY extension
controls.
.Pp
+(Debian-specific: This option does nothing in the default configuration: it
+is equivalent to
+.Dq Cm ForwardX11Trusted No yes ,
+which is the default as described above.
+Set the
+.Cm ForwardX11Trusted
+option to
+.Dq no
+to restore the upstream behaviour.
+This may change in future depending on client-side improvements.)
+.Pp
.It Fl y
Send log information using the
.Xr syslog 3
diff --git a/ssh_config b/ssh_config
index 228e5ab..c9386aa 100644
--- a/ssh_config
+++ b/ssh_config
@@ -17,9 +17,10 @@
# list of available options, their meanings and defaults, please see the
# ssh_config(5) man page.
-# Host *
+Host *
# ForwardAgent no
# ForwardX11 no
+# ForwardX11Trusted yes
# RhostsRSAAuthentication no
# RSAAuthentication yes
# PasswordAuthentication yes
@@ -48,3 +49,7 @@
# VisualHostKey no
# ProxyCommand ssh -q -W %h:%p gateway.example.com
# RekeyLimit 1G 1h
+ SendEnv LANG LC_*
+ HashKnownHosts yes
+ GSSAPIAuthentication yes
+ GSSAPIDelegateCredentials no
diff --git a/ssh_config.5 b/ssh_config.5
index d4928b8..81b9b74 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -74,6 +74,22 @@ Since the first obtained value for each parameter is used, more
host-specific declarations should be given near the beginning of the
file, and general defaults at the end.
.Pp
+Note that the Debian
+.Ic openssh-client
+package sets several options as standard in
+.Pa /etc/ssh/ssh_config
+which are not the default in
+.Xr ssh 1 :
+.Pp
+.Bl -bullet -offset indent -compact
+.It
+.Cm SendEnv No LANG LC_*
+.It
+.Cm HashKnownHosts No yes
+.It
+.Cm GSSAPIAuthentication No yes
+.El
+.Pp
The configuration file has the following format:
.Pp
Empty lines and lines starting with
@@ -721,7 +737,8 @@ token used for the session will be set to expire after 20 minutes.
Remote clients will be refused access after this time.
.Pp
The default is
-.Dq no .
+.Dq yes
+(Debian-specific).
.Pp
See the X11 SECURITY extension specification for full details on
the restrictions imposed on untrusted clients.
diff --git a/sshd_config b/sshd_config
index 64786c9..d8338db 100644
--- a/sshd_config
+++ b/sshd_config
@@ -125,7 +125,7 @@ UsePrivilegeSeparation sandbox # Default for new installations.
#Banner none
# override default of no subsystems
-Subsystem sftp /usr/libexec/sftp-server
+Subsystem sftp /usr/lib/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
diff --git a/sshd_config.5 b/sshd_config.5
index 0828592..0be7250 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -57,6 +57,31 @@ Arguments may optionally be enclosed in double quotes
.Pq \&"
in order to represent arguments containing spaces.
.Pp
+Note that the Debian
+.Ic openssh-server
+package sets several options as standard in
+.Pa /etc/ssh/sshd_config
+which are not the default in
+.Xr sshd 8 .
+The exact list depends on whether the package was installed fresh or
+upgraded from various possible previous versions, but includes at least the
+following:
+.Pp
+.Bl -bullet -offset indent -compact
+.It
+.Cm ChallengeResponseAuthentication No no
+.It
+.Cm X11Forwarding No yes
+.It
+.Cm PrintMotd No no
+.It
+.Cm AcceptEnv No LANG LC_*
+.It
+.Cm Subsystem No sftp /usr/lib/openssh/sftp-server
+.It
+.Cm UsePAM No yes
+.El
+.Pp
The possible
keywords and their meanings are as follows (note that
keywords are case-insensitive and arguments are case-sensitive):
|
