Ethereal-users: [Ethereal-users] total byte count difference for t/ethereal / NAI sniffer / tcpd

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From: "gab.seun jones.ewulomi" <seun_ewulomi@xxxxxxxxxxx>
Date: Wed, 11 Feb 2004 18:14:14 +0000
Hi Guys,

Need advice as I dont know what to conclude

Scenario
I went to a customer site and did some packet captures usis NAI sniffer. I will use the logon-app.trc as an example. I basically captured packets while a user logged on to a remote application. The aim being how much traffic is generated while logging on to determine how much bandwidth is used.

1)i used tethereal/ethereal(same as the summary window i presume) to view the logon-app,trc file (output below and please correct me if I have misunderstood any part in my descriptions)

frame frames:303 bytes:29884(Total payload+headers)
 tr                                     frames:303 bytes:29884
   llc                                  frames:303 bytes:29884
     ip                                 frames:303 bytes:29884
       tcp                              frames:303 bytes:29884
data frames:214 bytes:24366 (total payload bytes)

2)using NAI sniffer I got 31096 bytes in total when you click on the statistics tab on NAI sniffer.

3)using tcpdump
12:38:40.760392 snap ip 10.101.2.161.3459 > 11.134.32.61.ica: P [tcp sum ok] 98260575:98260602(27) ack 3072908457 win 8458 (DF) (ttl 32, id 2330, len 67)

My understanding is

(27) - is the payload in bytes
len 67 - is total bytes payload+headers (I think this only adds the tcp and ip headers)

I then used a script using a combination of awk and sed to format and grab the columns with the total byte lengths for each frame e.g (len 67) for both src and dst e.g

tcpdump -r logon-app-trc.cap src <ip>  -vvv
tcpdump -r logon-app-trc.cap dst <ip> -vvv

and then added them all together and it gave me
23218 bytes in total

23218 bytes

Now judging by what I want done which is to determine the amount of bandwidth consumed on logon which of this is giving me a true picture in which I can use in my bandwidth calculation.

Any help or advice will be greatly appreciated on the best approach. And please correct me any where I might have mis-understood anything.

Regards,
Seun

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