Taylan Yetkin wrote:
> Both ping and traceroute  the host from fermi machines returns  
> success.  I need some time to understand the use of tcpdump.
> thanks,
> Taylan

There's a fair chance there's a problematic firewall rule. Some examples 
that can confuse the issue.

smtp connexions from some locations to my gateway are forward using a 
DNAT rule to an internal system. If the internal system's down, a "host 
unreachable" response goes back, but ping and traceroute would work.

When an unwelcome packet arrives at my gateway, I can choose to ignore 
it (DROP in iptables) or REJECT it. If I REJECT, I can add the excuse 
"icmp-host-unreachable."


A good start with tcpdump is something like this:

tcpdump -i eth0 -s 8888 host cvs-server

or use wireshark which has the same abilities and a GUI to guide the 
beginner.




-- 

Cheers
John

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