Re: network problems after RH 7.2 --> 9.0 upgrade

[Rick Stevens <rstevens vitalstream com>]

Thomas Walter wrote:
> Hi Gurus,
>
> I upgraded a Dell machine from RH7.2 --> 9.0. It seemed to go flawlessly
> but not I can't SSH into the machine, I get a "host unreachable" message.
>
> If I ping the machine I get the following response:
>
> ping -s graupel
> PING graupel: 56 data bytes
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=0. time=0. ms
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 602
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 601
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 607
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=1. time=0. ms
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=2. time=0. ms
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=3. time=0. ms
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 630
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 631
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 632
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=4. time=0. ms
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=5. time=0. ms
> 64 bytes from graupel.geo.hunter.cuny.edu (146.95.2.90): icmp_seq=6. time=0. ms
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 631
> ICMP Port Unreachable from gateway graupel.geo.hunter.cuny.edu (146.95.2.90)
>  for udp from moon.geo.hunter.cuny.edu (146.95.2.3) to
> graupel.geo.hunter.cuny.edu (146.95.2.90) port 630
>
> Any ideas what the problem might be?

Did you set up the Linux firewall?  If you selected anything other than
"None", the only thing that can get in is DNS (TCP/UDP port 53).

Try this command to turn off the firewall:

	# /etc/rc.d/init.d/iptables stop

then try your ping and/or SSH.  If that works, then you need to run
"redhat-config-firewall" to poke holes in the firewall for TCP port 22
for ssh to work.  Note that "redhat-config-firewall" (aka "lokkit")
does NOT read the current firewall configuration.  It starts off by
assuming "High" security (EVERYTHING is blocked).  You must poke holes
in it.

I'd suggest downloading firestarter.  It's a much more capable GUI-based
firewall configuration tool than "lokkit" is.  The homepage for it is:

	http://firestarter.sourceforge.net.
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- Rick Stevens, Senior Systems Engineer     rstevens vitalstream com -
- VitalStream, Inc.                       http://www.vitalstream.com -
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-    "Hello. My PID is Inigo Montoya.  You `kill -9'-ed my parent    -
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