openssh unix dev - Jun 2002 - ssh hang on wrong port - is it a bug ?

Hi,

ssh client program seems to hang when specified a wrong port no (port on
which some other server, like telnetd is running).
"netstat -an" shows the connection is established.
I expect the ssh program to report invalid server msg and exit.
Is this a bug or known behaviour ???

I have attached the -v -v -v output.

Thanks,
Hari


[hari at linux ssh]$ /usr/bin/ssh -v -v -v -p 23 hari at 192.168.0.3
SSH Version OpenSSH_2.1.1, protocol versions 1.5/2.0.
Compiled with SSL (0x0090581f).
SSH Version OpenSSH_2.1.1, protocol versions 1.5/2.0.
Compiled with SSL (0x0090581f).
SSH Version OpenSSH_2.1.1, protocol versions 1.5/2.0.
Compiled with SSL (0x0090581f).
debug: Reading configuration data /etc/ssh/ssh_config
debug: Applying options for *
debug: Seeding random number generator
debug: ssh_connect: getuid 502 geteuid 0 anon 0
debug: Connecting to 192.168.0.3 [192.168.0.3] port 23.
debug: Allocated local port 1023.
debug: Connection established.

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> Hari wrote:
> ssh client program seems to hang when specified a wrong port no (port
> on which some other server, like telnetd is running).
Don't do that, then.
> "netstat -an" shows the connection is established.
> I expect the ssh program to report invalid server msg and exit.
> Is this a bug or known behaviour ???
ssh probably waiting for the SSH server banner. telnetd is probably
waiting for a response to telnet option negotiation. Stalemate.

A quick experiment here shows the same behaviour for ftp & http servers.
I expected it for http (it doesn't say anything when you connect so is
indistinguishable from a slow ssh server) but I would have thought the
ftp server banner would have caused ssh to abort (like sshd does).

-- 
Darren Tucker (dtucker at zip.com.au)
GPG Fingerprint D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

% telnet localhost ftp
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 foobar FTP server (Version 5.60) ready.
^]quit

Like Darren Tucker claims, FTPD prints the FTP banner and
waits, so of course, the telnet client "hangs;" it hangs
waiting for you, the user, to do something. I chose to quit
the session, as you can see. You chose to log in.

Nico
--  
> -----Original Message-----
> From: Gary E. Miller [mailto:gem at rellim.com]
> Sent: Monday, June 17, 2002 2:05 PM
> To: Darren Tucker
> Cc: openssh-unix-dev at mindrot.org
> Subject: Re: ssh hang on wrong port - is it a bug ?
> 
> 
> Yo Darren!
> 
> On Mon, 17 Jun 2002, Darren Tucker wrote:
> 
> > Telnetting into an FTP server prints the banner and hangs.
> 
> Uh no.  I have many times telneted in to an FTP server for debugging.
> 
> FTP is just looking for ASCII commands.  If you type the 
> right things then
> it will just work.
> 
> root at ratbert:~# telnet localhost ftp
> Trying 127.0.0.1...
> Connected to localhost.
> Escape character is '^]'.
> 220 ProFTPD 1.2.4 Server (ProFTPD Default Installation) 
> [ratbert.rellim.com]
> USER gem
> 331 Password required for gem.
> PASS !Kimmy7
> 230 User gem logged in.
> 
> RGDS
> GARY
> --------------------------------------------------------------
> -------------
> Gary E. Miller Rellim 20340 Empire Blvd, Suite E-3, Bend, OR 97701
> 	gem at rellim.com  Tel:+1(541)382-8588 Fax: +1(541)382-8676
> 
> _______________________________________________
> openssh-unix-dev at mindrot.org mailing list
> http://www.mindrot.org/mailman/listinfo/openssh-unix-dev
> 
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