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Network Troublshooting => Linux Servers Support => Topic started by: jmaitzen on December 02, 2008, 04:32:02 PM

Title: ICMP Checksum is wrong
Post by: jmaitzen on December 02, 2008, 04:32:02 PM
Intermittently receive ICMP Checksum is wrong when using traceroute to t-shoot.  Pinging the address first *seems* to resolve this issue. Anyone have any ideas?

MBoyle reported this same issue on Sept 10 2008. Any responses to this post?
Title: Re: ICMP Checksum is wrong
Post by: Ricky on December 06, 2008, 08:48:17 AM
Which OS you have ?  Still facing same problem ?
Title: Re: ICMP Checksum is wrong
Post by: jmaitzen on December 07, 2008, 02:00:43 AM
RHEL 4.5. Yes still having the problem. Perhaps I should research how traceroute works, but was hoping someone had seen this before.
Title: Re: ICMP Checksum is wrong
Post by: Ricky on December 07, 2008, 02:19:22 AM
Possible reason is that something is mangling the packets ie. if packet size mismatches then you receive such errors. Also, another reason is that default packet size is not sufficient enough then too it gives this error. However, it is also most possible reason in your case as you do not get above error if you ping first. And reason might be that when you PING first, system automatically determines required ICMP packet size for that particular host hence you do not get error afterwards.

However, reading elsewhere on web, it was found to be a bug in traceroute with CentOS4.x , since centOS is derived from RHEL, so same might goes with RHEL too. You may try to get most recent traceroute binary and see if it is solved.