-----Original Message-----
From: Andrea Giuliano [mailto:a.giuliano@iccu.sbn.it]
Sent: Thursday, July 01, 2004 4:30 AM
To: For users of Fedora Core releases
Subject: Tcpdump: "admin prohibited filter"
Dear all,
trying to make my ADSL connection working, I ran across this
suspicious line in the output from "tcpdump -i ppp0":
23:50:26.876061 IP 192.168.100.1 > 82.53.151.158: icmp 36:
host 217.144.248.190 unreachable - admin prohibited filter
The output is full of such lines (you can see the whole
output below). What do they mean? Who's the admin? Myself on
my local host or the admin of the remote host (in other
words, one of the ISP's admins)?
Since I simply cannot use the connection, even it seems to be
up and running, I was wondering if this messages could hide
the actual cause of my problems: maybe my ISP has made some
changes that prevent me from use the line effectively?
Please note the following:
1) I only had the connection working for one day, June 21, on FC1.
2) On June 22 I upgraded to FC2, and the connection became
slow, but still working.
3) Since June 23, the connection is definitely useless. No
host can be reached, not even the DNS server of my ISP, as
listed in the syslog after the ppp0 interface has come up.
Best regards.
--
Andrea Giuliano, Ph. D.
ICCU - Istituto Centrale per il Catalogo Unico
Viale Castro Pretorio 105, Rome - ITALY
Tel. +39064989509, Fax +39064059302
Hi,
The message means there's some sort of firewall, IP filtering setup
somewhere along the way from your host to the destination for ICMP messages,
such as a IPTABLES rule to block ICMP traffic, nothing suspicious.
You can test this by setup IPTABLES port filtering on one host and do a
tcpdump from another host, try access the port at the same time, you will
see similar messages.
Yang