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 by default.

ssh: Include /etc/ssh/ssh_config.d/*.conf.

sshd: Enable PAM, disable ChallengeResponseAuthentication, and disable
PrintMotd.

sshd: Enable X11Forwarding.

sshd: Set 'AcceptEnv LANG LC_*' by default.

sshd: Change sftp subsystem path to /usr/lib/openssh/sftp-server.

sshd: Include /etc/ssh/sshd_config.d/*.conf.

Document all of this.

Author: Russ Allbery <rra@debian.org>
Forwarded: not-needed
Last-Update: 2020-10-18

Patch-Name: debian-config.patch

1 files changed, 12 insertions, 6 deletions

diff --git a/sshd_config b/sshd_config
index 2c48105f8..459c1b230 100644
--- a/sshd_config
+++ b/sshd_config
@@ -10,6 +10,8 @@
 # possible, but leave them commented.  Uncommented options override the
 # default value.
 
+Include /etc/ssh/sshd_config.d/*.conf
+
 #Port 22
 #AddressFamily any
 #ListenAddress 0.0.0.0
@@ -57,8 +59,9 @@ AuthorizedKeysFile	.ssh/authorized_keys
 #PasswordAuthentication yes
 #PermitEmptyPasswords no
 
-# Change to no to disable s/key passwords
-#ChallengeResponseAuthentication yes
+# Change to yes to enable challenge-response passwords (beware issues with
+# some PAM modules and threads)
+ChallengeResponseAuthentication no
 
 # Kerberos options
 #KerberosAuthentication no
@@ -81,16 +84,16 @@ AuthorizedKeysFile	.ssh/authorized_keys
 # If you just want the PAM account and session checks to run without
 # PAM authentication, then enable this but set PasswordAuthentication
 # and ChallengeResponseAuthentication to 'no'.
-#UsePAM no
+UsePAM yes
 
 #AllowAgentForwarding yes
 #AllowTcpForwarding yes
 #GatewayPorts no
-#X11Forwarding no
+X11Forwarding yes
 #X11DisplayOffset 10
 #X11UseLocalhost yes
 #PermitTTY yes
-#PrintMotd yes
+PrintMotd no
 #PrintLastLog yes
 #TCPKeepAlive yes
 #PermitUserEnvironment no
@@ -107,8 +110,11 @@ AuthorizedKeysFile	.ssh/authorized_keys
 # no default banner path
 #Banner none
 
+# Allow client to pass locale environment variables
+AcceptEnv LANG LC_*
+
 # 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