Re: [gentoo-user] Sniffing / analysis of application / wifi packets on my LAN

[Jake Moe]

On 10/07/10 19:37, Stroller wrote:
> Hi there,
>
> I'm interested in the activity of an application which is running on my LAN, and was wondering if anyone could offer some quick pointers on the best tools for this these days. I've played with this some years ago, but only very superficially - I think I used wireshark back then.
>
> Ideally what I want to do is capture a big dump of the traffic over a couple of minutes (so it shouldn't be that much, right?) into a file and then analyse it afterwards based on destination IP, content &c. A couple of minutes should allow completion of at least 2 or 3 separate interactions with the server.
>
> The network is mine, as is the device from which I'm capturing the data. I have a Belkin F5D7010 wifi card, which I think is based on a RaLink rt2x00 (rt2400 / rt2500) chipset, and I have my network's WPA key, so I think I can just set the wifi card in passive mode for sniffing. I'm pretty sure I experimented with this card in passive mode before, some years ago. Alternatively, I think I can plug the wifi access-point into my PC, bridge it to a second wired NIC and sniff what's going across the bridge (but I don't think this should be necessary).
>
> What I'm expecting to see is some image, audio & html files &/or xml data transferred, and ideally I'd like to be able to extract it all and view it in its original format.
>
> There's likely to be some inevitable other activity on the wLAN whilst this is happening - I'll try to minimise this, but I think the tools should be able filter out any crap I'm not interested in, right?
>
> I'd prefer as much as possible to use CLI tools for capturing / analysing the data.
>
> Thanks in advance for any quick pointers you can offer,
>
> Stroller.
>
>
As far as I'm aware, Wireshark is the standard for packet capture and
analysis.  It supports both capture and display filters, so you can
limit it to just what you're interested in.  If the client and server
are both on your LAN, then you should probably go ahead and capture
everything, and then use a display filter to limit it to just the hosts
you need.  That way, if for some reason you find you need to see what
else is going on on the network at a given time, the captured data is
still there, you just broaden the display filter.

As far as CLI tools go, sorry, I'm not sure what's available.  Never had
a need to look into those.  But Wireshark uses libpcap, and digging a
bit shows tcpdump, which is a CLI tool that uses libpcap to capture
data, so it may give you the same functionality.  I've never used it
though, so I can't help further.

Jake Moe