From 8698446b972003b63dfe5dcbdb86acfe986afb85 Mon Sep 17 00:00:00 2001 From: Colin Watson 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. sshd: Refer to /usr/share/doc/openssh-server/README.Debian.gz alongside PermitRootLogin default. Document all of this, along with several sshd defaults set in debian/openssh-server.postinst. Author: Russ Allbery Forwarded: not-needed Last-Update: 2015-08-19 Patch-Name: debian-config.patch --- readconf.c | 2 +- ssh_config | 7 ++++++- ssh_config.5 | 19 ++++++++++++++++++- sshd_config | 1 + sshd_config.5 | 25 +++++++++++++++++++++++++ 5 files changed, 51 insertions(+), 3 deletions(-) diff --git a/readconf.c b/readconf.c index 2ef8d7b..66a62f2 100644 --- a/readconf.c +++ b/readconf.c @@ -1748,7 +1748,7 @@ 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_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 3bd80fd..da8e544 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 @@ -715,7 +731,8 @@ 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 a71ad19..3391233 100644 --- a/sshd_config +++ b/sshd_config @@ -41,6 +41,7 @@ # Authentication: #LoginGraceTime 2m +# See /usr/share/doc/openssh-server/README.Debian.gz. #PermitRootLogin yes #StrictModes yes #MaxAuthTries 6 diff --git a/sshd_config.5 b/sshd_config.5 index 453d741..db1f2fd 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):