> -----Original Message----- > From: Andrea Giuliano [mailto:a.giuliano@xxxxxxxxxxx] > 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
