Network Issue possibly from ICMP host unreachables

Network Issue possibly from ICMP host unreachables

Post by Loren Ama » Tue, 24 Feb 2004 11:10:34



I'm having a network issue with a Linux system. The system is Redhat
7.2 with Kernel 2.4.7-10 It communicates with other systems that are a
couple of router hops away. Whenever there is a communications problem
between the routers, the Linux box seems permanently unable to
communicate with the other systems from that point on until I add or
remove a static host route. It doesn't matter if it's unnecessary or
if I add or remove. Just the fact that I've manipulated the routing
table seems to bring back connectivity. I suspect that it's host
unreachables from the upstream router, but I'm not sure. Anyone see
this before? Thanks.
 
 
 

Network Issue possibly from ICMP host unreachables

Post by ynotsso » Tue, 24 Feb 2004 16:58:41



Quote:> I'm having a network issue with a Linux system. The system is Redhat
> 7.2 with Kernel 2.4.7-10 It communicates with other systems that are a
> couple of router hops away. Whenever there is a communications problem
> between the routers, the Linux box seems permanently unable to
> communicate with the other systems from that point on until I add or
> remove a static host route. It doesn't matter if it's unnecessary or
> if I add or remove. Just the fact that I've manipulated the routing
> table seems to bring back connectivity. I suspect that it's host
> unreachables from the upstream router, but I'm not sure. Anyone see
> this before? Thanks.

Choose the variant within the brackets that fits:

ftp://rpmfind.net/linux/redhat/updates/7.2/en/os/i[356]86/kernel-2.4.20-28.7
.i[356]86.rpm

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1. ICMP Destination Unreachable (Host Unreachable) [**] [Solved!!!]

Hello to you all.

I had some problems with the IDS alerts in snort regarding the subject
of this post.

 ICMP Destination Unreachable (Host Unreachable) [**]

Well, it seems to be solved here, and I did solve it like this.

1. go to your adsl/router
2. fill in dns properties from your dhcp dns server the correct dns
domain name of your host.
3. save this configuration.

And you are not longer troubled with the ICMP unreachable host
messages.

It is finally a bit quiet in te logs, and also the spp portscan
activities are gone.

Still I am curious how this exactly works, and if my solution helped
some of you, and if it is a correct solution I have applied???

Because maybe I am introducing a security related flaw, what I don't
like ofcourse, because maybe it was alright that the Snort IDS was
generating these alerts.

Well, I hope some of you will send a reply to me with some
backgrounds, and some advice if neccesary.

Just send a copy to my e-mail address if it helped you, or you have
something to say about this post.

Have a nice day you all!

Wouter Jan Wessels.

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