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Old 04-12-2013, 06:05 AM   #1
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Registered: Apr 2013
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[RedHat] ARP issue


[Edit] Know issue for QRadar 7.1 running on RedHat 6.2.

I am setting up a new server with two network interfaces.
These interfaces are on different subnets, and connected to the same firewall.

I'm trying to reach a remote IP.
It works fine from the first interface.

The second interface however, is making ARP requests instead of contacting the default gateway.
Using the same cable, and a laptop with the same IP setting as this second server interface, I can join the remote IP, so I would say it is not a connectivity/firewall issue.

I have tried several things without success so far

Any idea?

Thank you


Last edited by Wanou85; 04-17-2013 at 07:24 AM. Reason: OS added
Old 04-13-2013, 10:21 AM   #2
Registered: May 2008
Location: Toronto
Distribution: Centos && Debian
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The second interface however, is making ARP requests instead of contacting the default gateway.
Even to contact default gateway, it needs to send ARP request to know MAC address of default gateway. When a host needs to send packet/Frame to default gateway, at first it needs to know MAC address of default gateway. Host looks first at its own ARP table in cache. If it could not find MAC address of default gateway in its own MAC address table, then it needs to send ARP broadcast. So there is nothing wrong if it sends ARP request.

There may be misconfigured networking or routing issue on the "new server". You can show here routing table and network interface configuration to get the solution. Also specify which version of RedHat you are using.
Old 04-17-2013, 07:23 AM   #3
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Hello, thank you very much for your reply.
I have heard from the OS provider (IBM) and this is a know issue for the specific OS that I'm using.
It cannot do IP spoofing in certain scenarios such as the one I'm using.
Product: Qradar 7.1
Thanks again!


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