[Snort-users] Everything being triggered as 1:486:4 ICMP unreachable

David Ryan David.Ryan at ...13912...
Tue Jun 5 06:17:14 EDT 2007


Todd,

Thanks for the reply.  It was indeed a firewall issue - the device I was scanning was sending ICMP Host Administratively Unreachable packets when I tried certain scans, so I was seeing those packets.  As per the detail below I wasn't seeing the original traffic because of a problem with the _NET definitions.

Thanks,

David
-----Original Message-----
From: Todd Wease [mailto:twease at ...1935...]
Sent: 30 May 2007 13:15
To: David Ryan
Cc: snort-users at lists.sourceforge.net
Subject: Re: [Snort-users] Everything being triggered as 1:486:4 ICMP unreachable

David Ryan wrote:
>
> All,
>
>
>
> To partly reply to my own question - one of my flaws was keeping
> $HOME_NET as 10.0.0.0/8 - this prevented most of my test traffic from
> triggering since my tests were coming from $HOME_NET and not
> $EXTERNAL_NET.  This was significant where the rule I was testing was
> of the form $EXTERNAL_NET -> $HOME_NET

[SNIP]
>
> David
>

Sounds like it might be a firewall issue.  This response is usually sent
by a firewall to say that it's filter won't allow communication with
that host/port.  It may be allowing ssh to that host (port 22) and may
be allowing pings, but not allowing the host/port combo used in your test.

Todd

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