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Old 08-20-2009, 07:57 AM   #1
Registered: Sep 2008
Posts: 81

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unable to communicate with Linux machine

Hi all,

I installed red hat 2.6.9-5 and when I am trying to ping it.I am able to ping any other machine in the network but unable to do vice-versa(means unable to ping this machine from any other machine) and getting the message --
[root@mglinux ~]# ping
PING ( 56(84) bytes of data.
From icmp_seq=1 Destination Host Unreachable
From icmp_seq=2 Destination Host Unreachable
From icmp_seq=3 Destination Host Unreachable
please provide your valuable suggestions ...
Old 08-20-2009, 08:24 AM   #2
Registered: Sep 2007
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Lets see your firewall config - it's probably blocking ICMP.

the firewall config is in /etc/sysconfig/iptables
Old 08-20-2009, 08:27 AM   #3
Registered: Aug 2005
Location: /home/teebones
Distribution: sometimes this, sometimes that..
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can the machine (linuxbox) ping the others? (if that's the case, then as the previous poster mentioned, icmp echo reply is blocked.
however, if the machine cannot ping to others.. then it's likely the NIC has been initialized. (started up)

try: service network start, or service network restart (and check the output it gives)
or try ifup eth0 (first networkcard/device on the system, eth1 is second device etc etc)

you can view the config that the nic(s) have, by issueing:
ifconig -a

also make sure the cabling is correct.

Last edited by teebones; 08-20-2009 at 08:29 AM.
Old 08-20-2009, 09:32 AM   #4
Registered: Sep 2008
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how to check that it is blocking ICMP or not?

Yes,I am able to ping other machines but can't from other machines.
Old 08-20-2009, 10:05 AM   #5
Registered: Oct 2006
Location: Utah
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Perhaps you could post the output of the following command:

iptables -L

or like Admiral_beotch suggested take a look at /etc/sysconfig/iptables or better yet post the contents and somebody will be able to help you.


Old 08-20-2009, 10:10 AM   #6
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If you've just installed the system, then selinux will probably be enforcing by default. You can turn it off with...

echo "0" > /selinux/0

..then try and access your machine again.


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