Re: Why tcpdump don't work?

2008-08-28 Thread Chuck Swiger 

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 

[ ... ]
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 

Regards,
--
-Chuck

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Why tcpdump don't work?

2008-08-28 Thread EdwardKing 
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 

#ifconfig
le0: flags=8943 metric 0 mtu 
1500
 options=8
 ether 00:0b:31:76:35:31
 inet6 fe80::20c:29ff:fe76:356a%le0 prefixlen 64 scopeid 0x1 
 inet 172.0.10.2 netmask 0xff00 broadcast 172.0.10.255
 media: Ethernet autoselect
 status: active
plip0: flags=108810 metric 0 mtu 1500
lo0: flags=8049 metric 0 mtu 16384
 inet6 ::1 prefixlen 128 
 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3 
 inet 127.0.0.1 netmask 0xff00 

#tcpdump tcp port  and host 172.0.10.2
tcpdump:verbose output suppressed,use -v or -vv for full protocol decode 
listening on le0,link-type EN10MB (Ethernet),capture size 96 bytes

#tcpdump -v tcp port  and host 172.0.10.2
tcpdump:listening on le0,link-type EN10MB (Ethernet),capture size 96 bytes

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? 

Thanks!


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