PuTTY Fatal Error: Unknown network error.

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Putty Version 0.53b
OS  Windows98
Protocol:  SSH
Trying to connect to RedHat 9 2.4.20-6
Entire log file:
=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2003.07.21 19:48:00 ~=~=~=~=~=~=~=~=
Event Log: Writing new session log (SSH packets mode) to file: C:\putty.log
Event Log: Looking up host ""
Event Log: Connecting to port 22
Event Log: Unknown network error

1. Open Start->Programs->PuTTY->PuTTY
2.  Host name Port 22  SSH Close window only on clean exit
     Logging:  Log SSH packet data
     Always overwrite it.
     Preferred SSH protocol version:  I tried 1 only, 1 and 2
     All else is default
3.  Click on Open
4.  Wait a minute or two.
5.  Black screen opens
6.  Window comes back with heading PuTTY Fatal Error and Red X and message:
Unknown network error.  Button says OK.
7.  Click on OK button, and that's it.

I checked the network connection and am able to ping the Red Hat PC.  I am
also able to ping the PuTTY PC from my Red Hat PC, so ping works both ways.

I'd appreciate any help you can give me.

Re: PuTTY Fatal Error: Unknown network error.

Trace the relevant network activity on both sides, and find out what
packets are or are not getting through.

  Richard Silverman

Re: PuTTY Fatal Error: Unknown network error.

    sp5> I could sure use some help in refining the words "relevant" and
    sp5> "what packets".  I am able to ping from my Windows PC to the
    sp5> Linux PC and from Linux PC to the Windows PC.  Other than that,
    sp5> what is the relevant network activity on the Linux side and what
    sp5> is the relevant network activity on the Windows side?  Likewise,
    sp5> what packets am I looking for, and what tools are best to find
    sp5> them?

The successful pings show that the hosts are reachable to one another;
however, something is apparently preventing the SSH traffic (which is
different from that of "ping") from working.  The relevant activity is the
setup of a TCP connection from an ephemeral port on the client to port 22
on the server.  Use a sniffer (e.g. tcpdump, Ethereal) on each side to see
what's happening.  Something like:

server# tcpdump -n host <client> and port 22 or icmp

client: Use Ethereal to capture everything, then examine it with the GUI.

Of course, this is only a guide, since the details such as the of number
of network interfaces on the boxes may require different commands, etc.

If packets leave the client but never arrive at the server, for example,
then there may be an intervening firewall dropping them.  Note that
"intervening" might mean a iptables packet filter operating on the same

  Richard Silverman

Re: PuTTY Fatal Error: Unknown network error.

Thanks guys,
The ethereal sniffer sounds like something worth having.  Meanwhile, I
discovered my problem.  It had everything to do with the firewall setup.  I
used "medium" firewall protection on installation, and that did not allow
for any ssh traffic.  So, I got this part fixed.  Now on to the next
problem.  I appreciate this very helpful forum.
Thanks again.
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