Date: Mon, 27 Dec 2004 19:30:30 -0500 From: Doug Lee <dgl@dlee.org> To: freebsd-questions@freebsd.org Subject: Tcpdump says I'm getting incomplete packets; how to find the culprit? Message-ID: <20041228003030.GL900@kirk.dlee.org>
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I use FreeBSD 4.10-STABLE as a nat/firewall box. When connected to DSL, I got fast web surfing but many gaps in incoming audio traffic using some audio software. I switched to cable, and now audio works great, but at least when I pop open pages in Lynx right on the FreeBSD box, I often experience five-second delays--one at "202 OK" and one or more during the loading of the page. Tcpdump reports that I'm receiving incomplete packets, so I assume the five-second delays are timeouts on my box before a request for packet resends. I'm afraid this is a black art of sorts, but in case there's a well-known solution, I'm all ears: Is there a fairly straight-forward way to track down and/or fix this kind of packet truncation issue? I don't know if the packets are getting truncated before they reach me or somehow on my box. More info on my topology: DSL was PPPoE straight into the fbsd box via a crossed Ethernet cable; the cable modem is connected via the same cable and uses DHCP. Fwiw, the NAT is served to Windows boxen from a second NIC in the fbsd box. The drivers for the two NICs are ed for the Internet side and dc for the local side. For PPPoE, I was using mpd. I use ipfw/natd for firewalling and NAT. I can surely provide more details to anyone who needs them. Please Cc me on replies (I hope this is not rude to ask; I'm just afraid of missing answers). Thanks much. -- Doug Lee dgl@dlee.org http://www.dlee.org Bartimaeus Group doug@bartsite.com http://www.bartsite.com "There's no limit to what a man can do or where he can go if he doesn't mind who gets the credit." Ronald Reagan
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