Ethereal-users: RE: [Ethereal-users] Monitoring with Ethereal

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From: "McNutt, Justin M." <McNuttJ@xxxxxxxxxxxx>
Date: Thu, 31 Jul 2003 08:28:46 -0500
Title: Message
Yes.  Do something like this:
 
tethereal -n -a filesize:10000 -b 20 -w /your/output/files/go/here/capture.file.name -f "host <ip1> or host <ip2>"
 
So you'll see all traffic to AND from host "ip1" and you'll see all traffice to AND from host "ip2".  Since the traffic between these two hosts is okay, you could rule out those streams by making the capture filter longer:
 
-f "(host <ip1> or host <ip2>) and not (host <ip1> and host <ip2>)"
 
Anyway, this capture would run all the time, dumping the output into 20 files (-b 20), max size each is 10MB (-a filesize:10000), and it would write them as "capture.file.name.NNN" in the directory "/your/output/files/go/here".  :-)  Modify as appropriate.
 
Now, when you go to *read* the things, you can do one of two things.
 
1)  Stop the capture.  Tethereal will rename all of the files to a timestamp-based name.  Use mergecap to make them one big capture file (if you want) and load it up.
 
2)  Don't bother stopping the capture.  Just copy the files out of the ring buffer and merge them, or use mergecap on them where they are (since the originals are not modified), and load it up.  You'll get errors about the last packet in each file, since it'll probably be a partial packet.
 
Do NOT MOVE the files out of an active ring buffer.  Ethereal keeps the files open.  If you move them, it'll really *@#& things up.  Copying them is fine.  Moving them is bad.
 
Note that I stuck the "-n" on the original capture to disable name resolution.  Don't worry.  The name resolution stuff doesn't go in the capture files anyway, so it's a waste to have tethereal looking up names at capture time.  Just have name lookups enabled when you go to read the files later and you'll still see all of the names.
 
Hope that helps!
 
--J
-----Original Message-----
From: Michel Vanden Bossche [mailto:m.vdb@xxxxxxx]
Sent: Wednesday, July 30, 2003 10:25 AM
To: ethereal-users@xxxxxxxxxxxx
Subject: [Ethereal-users] Monitoring with Ethereal

Is it possible to filter only a few IP ranges (partners accessing the Intranet) with a name resolution (partner name)?
This would allow to monitor if authorized partner access only their authorized resources on the Intranet.
 
Michel