Date: Thu, 3 Oct 2002 11:21:35 +1000 (EST) From: Tony Maher <tonym@biolateral.com.au> To: peter.jeremy@alcatel.com.au Cc: stable@FreeBSD.ORG Subject: Re: 'losing' every second packet Message-ID: <200210030121.g931LZWv047336@dt.home> In-Reply-To: <20021003003859.GN495@gsmx07.alcatel.com.au>
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Peter,
> I'm also using Optus cable, but with -STABLE from about a week ago and
> IPfilter rather than ipfw. (I found that ipfw+natd+keep-state didn't
> work).
Ok sounds like we are running almost identical release so its good to
know there is an alternative. (BTW ipfw+natd+keep-state
have been working fine for me for past 12 months until this last month)
> I haven't seen this problem and can't suggest any obvious
> cause within FreeBSD. It is possible that Optus have added something
> to their firewall to 'discourage' incoming setup packets (to enforce
> their "no servers" policy).
Hard to see how this could be the case ... hmmm unless they added a 50%
drop rate on a destination after observing some form of 'unlawful'
behaviour. Not that I am running any servers (well except sshd and
hosts.allow restricts it to just my work machines).
Using ssh does not seem to trigger it.
Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Interesting ports on gw.optus (210.49.XXX.XX):
(The 1599 ports scanned but not shown below are in state: filtered)
Port State Service
22/tcp open ssh
113/tcp closed auth
No exact OS matches for host (If you know what OS is running on it,
> All I can suggest is running tcpdump on your firewall and a remote
> machine and studying the packet loss when you send various packets
> between the machines (ping, UDP and TCP). This might identify where
> (in which direction) the packet loss is occurring.
Packet loss appears to be independent of protocol, see it with ping,
ssh (tcp) and games (udp).
But yes - with long weekend I should get some time for trawling thru packets
:-)
thanks!
--
tonym
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