[ee122] Unable to capture any packets

[Simon Tan]

Capturing on the file_recv receiving port does capture packets, but we  
found that we get more complete results (i.e. we capture both outgoing and  
incoming packets coming on both sender and receiver sides) if we capture  
on the MNLDaemons' listening ports.

However, for some reason, capturing on the MNLDaemon's ports didn't  
capture any packets at first -- we had to add 1 to the port numbers  
(MNLDaemon's listening port + 1)  to capture packets. This seems  
completely ridiculous, but it actually worked (in our case at least). Can  
anyone give us insight as to why? (Is MNLDaemon buggy?)


On Mon, 10 Dec 2007 15:39:08 -0800, Linda Sha <lindablus at berkeley.edu>  
wrote:

> Hi,
>
> I have a question about tcpdump:
> When I specify a port number for tcpdump, I'm not able to capture any
> packets. When I take out the port number, I get ssh encrypted messages.  
> I'm
> not sure what happened.
>
> /share/b/ee122/tcpdump -s 0 -w trace host c199.eecs.berkeley.edu and port
> 9468
> tcpdump.sun4u: listening on qfe0, link-type EN10MB (Ethernet), capture  
> size
> 65535 bytes
> 0 packets captured
> 34224 packets received by filter
> 0 packets dropped by kernel
>
> ##port 9468 is the port my server is listening on.
>
> Thanks.
>
> Linda



-- 
~Simon Tan >> undergraduate at UC Berkeley
Source: simtan at berkeley.edu