- Help: meaning of ICMP_UNREACH message from firewall
- Posted by Zak on April 4th, 2006
I can't understand what to do about this ICMP message from my
Filseclab software firewall:
Application: SYSTEM
Direction: In
Remote IP: rz.vrx.net
Status/Bytes: RECV/70
Description: ICMP_UNREACH[ICMP_UNREACH_PORT](bad port)|RT:9|
Presumably this has something to do with an ICMP packet not being
able to reach some port on my system. Can someone explain this a bit
more please.
And importantly, what can I do on Filseclab to overcome this?
If I turn my firewall OFF then DNS lookups seem to happen faster and
some (but not all) of the Usenet servers I belong to work faster. I
suspect that these trapped ICMP messages might have something to do
with the slowness I am getting.
- Posted by George Orwell on April 5th, 2006
Zak wrote:
Don't have a clue what Fileseclab even is, but the problem seems pretty
straight forward. Someone's blindly rejecting echo requests (pings) and
your software expects them. The "RT:9" suggests that the responding
machine is sending "Administratively Prohibited" type replies to pings,
which generally means some firewall not in "stealth" mode.
I think you answered your own question. Reconfigure your firewall to
properly respond to or pass echo requests if that's what all the evidence
tells you to do. <grin>
- Posted by Mailman on April 5th, 2006
On Tue, 04 Apr 2006 22:47:04 +0100, Zak wrote:
Not quite. What happened is that something on your machine tried to open
a connection to some remote system, and that one answered with a "port
unreachable" - nothing listening on the port or the port us blocked
(filtered). This is part of the normal (presumably TCP) negotiation.
Try looking up the ICMP types and decide which ones you want to allow in
(hint: a lot of them are undesirable, but this is not one of them).
--
Mailman
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- Posted by Zak on April 5th, 2006
On 05 Apr 2006, Mailman<mailman@anonymous.org> wrote:
This particular firewall does not permit me to choose which type of
ICMP it passes or rejects. So to avoid problems I set it to pass all
ICMP traffic.
But I stil get that wierd message. If I close the firewall down
completely then the app seems to communicate ok. Does this help
anyone to know what might be happening?
