Date: Thu, 28 Aug 2008 22:27:00 -0700 From: Chuck Swiger <cswiger@mac.com> To: EdwardKing <zhangsc@neusoft.com> Cc: FreeBSD <freebsd-questions@freebsd.org> Subject: Re: Why tcpdump don't work? Message-ID: <3DCA0239-52B5-4B04-8FAB-730FBAF85450@mac.com> In-Reply-To: <032001c90994$8cb3e760$3f83a8c0@neusofteaf5839> References: <032001c90994$8cb3e760$3f83a8c0@neusofteaf5839>
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Howdy-- On Aug 28, 2008, at 10:03 PM, EdwardKing wrote: > I have a server and a client,they use TCP to communication.For > example,when client send a message to server,the server return the > same message to client,then client show it.When client or server > shutdown,it will send FIN.So I want to use tcpdump to watch it. The > server and client in the same machine,the IP is 172.0.10.2 and the > port is 9999 > [ ... ] > when client and server communication or client shutdown,tcpdump > don't show any message! > Why? I am very puzzle with it! How to show server and client tcp > communication information by using tcpdump? If both client and server are running on the same machine, then the network traffic doesn't actually go through your le0 network interface-- instead, it uses the loopback interface, lo0, on IP 127.0.0.1. Try something more like: tcpdump -i lo0 -v tcp port 9999 Regards, -- -Chuck
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