How can I read pcap files in a friendly format?

Posted by Tony on Server Fault See other posts from Server Fault or by Tony
Published on 2009-07-09T21:17:49Z Indexed on 2012/11/26 11:10 UTC
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a simple cat on the pcap file looks terrible:

$cat tcp_dump.pcap

?ò????YVJ?
          JJ
            ?@@.?E<??@@
?CA??qe?U?????h?
.Ceh?YVJ??
          JJ
            ?@@.?E<??@@
CA??qe?U?????z?
.ChV?YVJ$?JJ
            ?@@.?E<-/@@A?CA??9????F???A&?
.Ck??YVJgeJJ@@.??#3E<@3{n??9CA??P???F???<K?
??`.Ck??YVJgeBB
               ?@@.?E4-0@@AFCA??9????F?P?????
.Ck???`?YVJ?""@@.??#3E?L@3?I??9CA??P???F?????
???.Ck?220-rly-da03.mx

etc.

I tried to make it prettier with:

sudo tcpdump -ttttnnr tcp_dump.pcap
reading from file tcp_dump.pcap, link-type EN10MB (Ethernet)
2009-07-09 20:57:40.819734 IP 67.23.28.65.49237 > 216.239.113.101.25: S 2535121895:2535121895(0) win 5840 <mss 1460,sackOK,timestamp 776168808 0,nop,wscale 5>
2009-07-09 20:57:43.819905 IP 67.23.28.65.49237 > 216.239.113.101.25: S 2535121895:2535121895(0) win 5840 <mss 1460,sackOK,timestamp 776169558 0,nop,wscale 5>
2009-07-09 20:57:47.248100 IP 67.23.28.65.42385 > 205.188.159.57.25: S 2644526720:2644526720(0) win 5840 <mss 1460,sackOK,timestamp 776170415 0,nop,wscale 5>
2009-07-09 20:57:47.288103 IP 205.188.159.57.25 > 67.23.28.65.42385: S 1358829769:1358829769(0) ack 2644526721 win 5792 <mss 1460,sackOK,timestamp 4292123488 776170415,nop,wscale 2>
2009-07-09 20:57:47.288103 IP 67.23.28.65.42385 > 205.188.159.57.25: . ack 1 win 183 <nop,nop,timestamp 776170425 4292123488>
2009-07-09 20:57:47.368107 IP 205.188.159.57.25 > 67.23.28.65.42385: P 1:481(480) ack 1 win 1448 <nop,nop,timestamp 4292123568 776170425>
2009-07-09 20:57:47.368107 IP 67.23.28.65.42385 > 205.188.159.57.25: . ack 481 win 216 <nop,nop,timestamp 776170445 4292123568>
2009-07-09 20:57:47.368107 IP 67.23.28.65.42385 > 205.188.159.57.25: P 1:18(17) ack 481 win 216 <nop,nop,timestamp 776170445 4292123568>
2009-07-09 20:57:47.404109 IP 205.188.159.57.25 > 67.23.28.65.42385: . ack 18 win 1448 <nop,nop,timestamp 4292123606 776170445>
2009-07-09 20:57:47.404109 IP 205.188.159.57.25 > 67.23.28.65.42385: P 481:536(55) ack 18 win 1448 <nop,nop,timestamp 4292123606 776170445>
2009-07-09 20:57:47.404109 IP 67.23.28.65.42385 > 205.188.159.57.25: P 18:44(26) ack 536 win 216 <nop,nop,timestamp 776170454 4292123606>
2009-07-09 20:57:47.444112 IP 205.188.159.57.25 > 67.23.28.65.42385: P 536:581(45) ack 44 win 1448 <nop,nop,timestamp 4292123644 776170454>
2009-07-09 20:57:47.484114 IP 67.23.28.65.42385 > 205.188.159.57.25: . ack 581 win 216 <nop,nop,timestamp 776170474 4292123644>
2009-07-09 20:57:47.616121 IP 67.23.28.65.42385 > 205.188.159.57.25: P 44:50(6) ack 581 win 216 <nop,nop,timestamp 776170507 4292123644>
2009-07-09 20:57:47.652123 IP 205.188.159.57.25 > 67.23.28.65.42385: P 581:589(8) ack 50 win 1448 <nop,nop,timestamp 4292123855 776170507>
2009-07-09 20:57:47.652123 IP 67.23.28.65.42385 > 205.188.159.57.25: . ack 589 win 216 <nop,nop,timestamp 776170516 4292123855>
2009-07-09 20:57:47.652123 IP 67.23.28.65.42385 > 205.188.159.57.25: P 50:56(6) ack 589 win 216 <nop,nop,timestamp 776170516 4292123855>
2009-07-09 20:57:47.652123 IP 67.23.28.65.42385 > 205.188.159.57.25: F 56:56(0) ack 589 win 216 <nop,nop,timestamp 776170516 4292123855>
2009-07-09 20:57:47.668124 IP 67.23.28.65.49239 > 216.239.113.101.25: S 2642380481:2642380481(0) win 5840 <mss 1460,sackOK,timestamp 776170520 0,nop,wscale 5>
2009-07-09 20:57:47.692126 IP 205.188.159.57.25 > 67.23.28.65.42385: P 589:618(29) ack 57 win 1448 <nop,nop,timestamp 4292123893 776170516>
2009-07-09 20:57:47.692126 IP 67.23.28.65.42385 > 205.188.159.57.25: R 2644526777:2644526777(0) win 0
2009-07-09 20:57:47.692126 IP 205.188.159.57.25 > 67.23.28.65.42385: F 618:618(0) ack 57 win 1448 <nop,nop,timestamp 4292123893 776170516>
2009-07-09 20:57:47.692126 IP 67.23.28.65.42385 > 205.188.159.57.25: R 2644526777:2644526777(0) win 0

Well...that is much prettier but it doesn't show the actual messages. I can actually extract more information just viewing the RAW file. What is the best ( and preferably easiest) way to just view all the contents of the pcap file?

UPDATE

Thanks to the responses below, I made some progress. Here is what it looks like now:

tcpdump -qns 0 -A -r blah.pcap
    20:57:47.368107 IP 205.188.159.57.25 > 67.23.28.65.42385: tcp 480
        0x0000:  4500 0214 834c 4000 3306 f649 cdbc 9f39  [email protected]
        0x0010:  4317 1c41 0019 a591 50fe 18ca 9da0 4681  C..A....P.....F.
        0x0020:  8018 05a8 848f 0000 0101 080a ffd4 9bb0  ................
        0x0030:  2e43 6bb9 3232 302d 726c 792d 6461 3033  .Ck.220-rly-da03
        0x0040:  2e6d 782e 616f 6c2e 636f 6d20 4553 4d54  .mx.aol.com.ESMT
        0x0050:  5020 6d61 696c 5f72 656c 6179 5f69 6e2d  P.mail_relay_in-
        0x0060:  6461 3033 2e34 3b20 5468 752c 2030 3920  da03.4;.Thu,.09.
        0x0070:  4a75 6c20 3230 3039 2031 363a 3537 3a34  Jul.2009.16:57:4
        0x0080:  3720 2d30 3430 300d 0a32 3230 2d41 6d65  7.-0400..220-Ame
        0x0090:  7269 6361 204f 6e6c 696e 6520 2841 4f4c  rica.Online.(AOL
        0x00a0:  2920 616e 6420 6974 7320 6166 6669 6c69  ).and.its.affili
        0x00b0:  6174 6564 2063 6f6d 7061 6e69 6573 2064  ated.companies.d

etc.

This looks good, but it still makes the actual message on the right difficult to read. Is there a way to view those messages in a more friendly way?

UPDATE

This made it pretty:

tcpick -C -yP -r tcp_dump.pcap

Thanks!

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