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!H on traceroute's first hop?
| Posted by frogfuzion, 03-03-2012, 04:25 PM | | Hi guys,
I'm still fairly with the whole network troubleshooting, I can't seem to get my head around this certain issue, because all of a sudden server Y couldn't reach server X anymore.
I did a traceroute from the server Y to server X and we got Host unreachable on the first hop. Has anyone seen this before and know how to solve it?
I'm not sure when we lost connectivity, but I suspect it may have started when I played with sysctl on server Y.
Thank you!
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| Posted by brianoz, 03-03-2012, 08:02 PM | | What firewall are you using? It's possible an automated firewall may have blocked your other server, sysctl is unlikely to block a server.
If you're using CSF, try "csf -g 1.2.3.4", replacing the IP with your other server IP, and if it's listed, try "csf -a 1.2.3.4" and/or add the IP to /etc/csf/csf.ignore.
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| Posted by frogfuzion, 03-03-2012, 11:06 PM | | I'm using regular iptables, as far as I'm aware it isn't blocking any IPs at the moment, it only has rules to allow incoming icmp 0,5,11, udp traceroute and allow incoming traffic to ports our application needs, all outgoing traffic allowed
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