Snapshot

[Aran Cox]

Well, I think I have managed to make my problem disapear, 
but first a little more background.  I'm currently under the
impression that the problems I've been having are related
to timing (does that qualify them as a race condition?) I could
*never* duplicate this problem while running sshd under the SCO 
OS debugger.  Not once!  Also, I could almost always duplicate the
problem if I gave the server (SCO OS 5.0.5) running sshd something
else to do in the background (like a find invocation, or compressing
a large amount of data.) 

After looking around the code for a while I saw the section on 
USE_PIPES in session.c in the do_exec_no_pty.  Since my problem
was related to pipes, (the program is dying on SIGPIPE) I thought
I'd try defining USE_PIPES and recompiling.  Now I cannot
duplicate the SIGPIPE (signal 13) problem with an sshd compiled
with USE_PIPES.  Of course, I don't understand exactly why this 
fixes my problem or if the solution is correct.  

I'll include the output of sshd -d for a successful run and
an unsuccessful one.  I was usually invoking ssh like so:
ssh -n -l root host ls -ld .

My system is i686-pc-sco3.2v5.0.5.  

I can understand why it's undesirable to apply a patch to
fix a problem that only one person can duplicate, so hopefully
this info will be useful to someone who can give me a clue
where to look next.  Has anyone really tried running SCO OS
5.0.5 as an sshd server and using the -n switch from the client
side?  It would make me feel less insane if someone would
try (possibly with a little load on the server since
that seems to make the problem occur more frequently) running
ssh -n host ls -ld . in a loop and seeing if they see any

Received disconnect: Command terminated on signal 13.

error messages.

cheers!

On Wed, Aug 30, 2000 at 11:29:25AM +1100, Damien Miller wrote:
> On Tue, 29 Aug 2000, Aran Cox wrote:
> 
> > This snapshot does not fix the (serious) problems I had with
> > the previous snapshot and p4.  
> > 
> > Please see my previous email to the list "Re: Test snapshost"
> > for details about the problems I've been having.  Does anyone
> > have any suggestions?  Has anyone duplicated this?
>  
> I haven't been able to duplicate this on Linux or Irix 5.3.
> 
> -d
> 
> -- 
> | "Bombay is 250ms from New York in the new world order" - Alan Cox
> | Damien Miller - http://www.mindrot.org/
> | Email: djm at mindrot.org (home) -or- djm at ibs.com.au (work)
> 
> 
> 
-------------- next part --------------
debug: sshd version OpenSSH_2.1.1p5
debug: Command 'ls -alni /var/log' exit status was 2
debug: Command 'tail -200 /var/log/messages' exit status was 2
debug: Command 'tail -200 /var/log/syslog' exit status was 2
debug: Seeded RNG with 32 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: read DSA private key done
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
Generating 768 bit RSA key.
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
RSA key generation complete.
debug: Server will not fork when running in debugging mode.
Connection from 172.16.10.59 port 724
debug: Client protocol version 1.5; client software version OpenSSH_2.1.1p5
debug: Local version string SSH-1.99-OpenSSH_2.1.1p5
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Sent 768 bit public key and 1024 bit host key.
debug: Encryption type: blowfish
debug: Received session key; encryption turned on.
debug: Installing crc compensation attack detector.
debug: Attempting authentication for root.
Failed rsa for ROOT from 172.16.10.59 port 724
Failed rsa for ROOT from 172.16.10.59 port 724
Accepted password for ROOT from 172.16.10.59 port 724
debug: session_new: init
debug: session_new: session 0
debug: Received request for X11 forwarding with auth spoofing.
debug: fd 5 setting O_NONBLOCK
debug: channel 0: new [X11 inet listener]
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Exec command 'ls -ld .'
debug: Entering interactive session.
debug: Received SIGCHLD.
debug: fd 11 setting O_NONBLOCK
debug: fd 13 setting O_NONBLOCK
debug: server_init_dispatch_13
debug: server_init_dispatch_15
debug: EOF received for stdin.
debug: tvp!=NULL kid 1 mili 100
debug: tvp!=NULL kid 1 mili 10
debug: tvp!=NULL kid 1 mili 100
debug: End of interactive session; stdin 0, stdout (read 56, sent 56), stderr 463 bytes.
debug: channel_free: channel 0: status: The following connections are open:

debug: Command exited with status 0.
debug: Received exit confirmation.
debug: xauthfile_cleanup_proc called
Closing connection to 172.16.10.59
debug: writing PRNG seed to file //.ssh/prng_seed
-------------- next part --------------
debug: sshd version OpenSSH_2.1.1p5
debug: Command 'ls -alni /var/log' exit status was 2
debug: Command 'ipcs -a' timed out
debug: Command 'tail -200 /var/log/messages' exit status was 2
debug: Command 'tail -200 /var/log/syslog' exit status was 2
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: read DSA private key done
debug: Seeded RNG with 30 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
Generating 768 bit RSA key.
debug: Seeded RNG with 30 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Command 'ipcs -a' timed out
debug: Seeded RNG with 30 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
RSA key generation complete.
debug: Server will not fork when running in debugging mode.
Connection from 172.16.10.59 port 963
debug: Client protocol version 1.5; client software version OpenSSH_2.1.1p5
debug: Local version string SSH-1.99-OpenSSH_2.1.1p5
debug: Seeded RNG with 29 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 29 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Sent 768 bit public key and 1024 bit host key.
debug: Encryption type: blowfish
debug: Received session key; encryption turned on.
debug: Installing crc compensation attack detector.
debug: Attempting authentication for root.
Failed rsa for ROOT from 172.16.10.59 port 963
Failed rsa for ROOT from 172.16.10.59 port 963
Accepted password for ROOT from 172.16.10.59 port 963
debug: session_new: init
debug: session_new: session 0
debug: Received request for X11 forwarding with auth spoofing.
debug: fd 5 setting O_NONBLOCK
debug: channel 0: new [X11 inet listener]
debug: Seeded RNG with 29 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 29 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Seeded RNG with 31 bytes from programs
debug: Seeded RNG with 3 bytes from system calls
debug: Exec command 'ls -ld .'
debug: Entering interactive session.
debug: fd 11 setting O_NONBLOCK
debug: fd 13 setting O_NONBLOCK
debug: server_init_dispatch_13
debug: server_init_dispatch_15
debug: EOF received for stdin.
debug: Received SIGCHLD.
debug: tvp!=NULL kid 1 mili 100
debug: End of interactive session; stdin 0, stdout (read 0, sent 0), stderr 463 bytes.
debug: channel_free: channel 0: status: The following connections are open:

Disconnecting: Command terminated on signal 13.
debug: Calling cleanup 0xa578(0x0)
debug: xauthfile_cleanup_proc called
debug: Calling cleanup 0x11af0(0x0)
debug: Calling cleanup 0x18c4c(0x0)
debug: Calling cleanup 0x1b658(0x0)
debug: writing PRNG seed to file //.ssh/prng_seed