sshd prints the motd with -t option

[Christian Kurz]

Hi,

and another interesting bug report, where I'm not sure what the correct
behaviour of openssh should be. Thanks for your comments:

> I find myself frequently using OpenSSH to log in and perform a single
> command (particularly in a script to perform some quick, simple task on
> multiple machines I administer).  If the '-t' option is not included, the
> behavior is no different than with the non-OpenSSH ssh inplementation.
> However, this causes problems when I need to enter a password for, say,
> sudo; the password is echoed back to the screen and the command fails.  If
> instead I enter 'ssh -t user at host command', sudo and others will work
> properly, but the motd is printed as well.  This adds significantly to the
> output to be human-parsed and makes it more difficult to discern what
> output came from which machine, as well as being different from the
> original ssh and ssh2 implementations.  Here is some sample output; first,
> an example of performing a command on a host running the original ssh
> implementation:

|bj at host01:~$ ssh host00 ls /
|Warning: Server lies about size of server host key: actual size is 1023
|bits vs.
| announced 1024.
|Warning: This may be due to an old implementation of ssh.
|bj at host00.do.main's password:
|bin
|boot
|cdrom
|dev
|etc
|floppy
|home
|initrd
|lib
|lost+found
|mnt
|proc
|root
|sbin
|tmp
|usr
|var
|vmlinuz
|vmlinuz.old
|bj at host01:~$ ssh -t host00 ls /
|Warning: Server lies about size of server host key: actual size is 1023
|bits vs. announced 1024.
|Warning: This may be due to an old implementation of ssh.
|bj at host00.do.main's password:
|bin          etc          lib          root         var
|boot         floppy       lost+found   sbin         vmlinuz
|cdrom        home         mnt          tmp          vmlinuz.old
|dev          initrd       proc         usr
|Connection to host00.do.main closed.
|bj at host01:~$

|Next, connecting to a host running OpenSSH's sshd:
|bj at host00:~$ ssh host01 ls /
|bj at host01's password:
|bin
|boot
|cdrom
|dev
|etc
|floppy
|home
|home.delete
|initrd
|lib
|lost+found
|mnt
|proc
|root
|sbin
|storage
|tmp
|usr
|var
|vmlinuz
|vmlinuz.old
|bj at host00:~$ ssh -t host01 ls /
|bj at host01's password:
|Last login: Sat Aug 12 18:20:18 2000 from some.host.do.main on pts/1
|Linux host01 2.2.5 #2 Wed May 24 19:31:11 EDT 2000 i686 unknown
 
|Most of the programs included with the Debian GNU/Linux system are
|freely redistributable; the exact distribution terms for each program
|are described in the individual files in /usr/doc/*/copyright
 
|Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
|permitted by applicable law.
|You have new mail.
|bin    dev     home         lib         proc  storage  var
|boot   etc     home.delete  lost+found  root  tmp      vmlinuz
|cdrom  floppy  initrd       mnt         sbin  usr      vmlinuz.old
|Connection to host01 closed.
|bj at host00:~$

|host00 is a slink system running the older implementation of ssh, and
|host01 is a potato system running OpenSSH.

|I would like to suggest that OpenSSH be modified to suppress printing the
|motd if the -t option is used and it is a non-login session, ie, the
|connection is opened for command processing only.

|bj at host00:~$ grep PrintMotd /etc/ssh/sshd_config
|PrintMotd yes

|bj at host01:~$ grep PrintMotd /etc/ssh/sshd_config
|PrintMotd no

Ciao
     Christian
-- 
          Debian Developer and Quality Assurance Team Member
    1024/26CC7853 31E6 A8CA 68FC 284F 7D16  63EC A9E6 67FF 26CC 7853
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