Hello, I was trying to analyze the traffic generated by this command: root@atena:~# dig rt-dq.quimica.ufpb.br @150.165.145.1
But I noticed that when the option '-w file' was not used, the tcpdump capture changed: ** WITH -w (2 packets captured): root@atena:~# tcpdump -pi eth0 port 53 -w dns.dump tcpdump: WARNING: eth0: no IPv4 address assigned tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes ^C2 packets captured 4 packets received by filter 0 packets dropped by kernel root@atena:~# tcpdump -r dns.dump reading from file dns.dump, link-type EN10MB (Ethernet) 09:27:36.961325 IP atena.nti.ufpb.br.53124 > rt-dq.quimica.ufpb.br.domain: 47498+ A? rt-dq.quimica.ufpb.br. (39) 09:27:36.964252 IP rt-dq.quimica.ufpb.br.domain > atena.nti.ufpb.br.53124: 47498*- 1/3/0 A 150.165.145.1 (107) ** WITHOUT -w (8 packets captured): root@atena:~# tcpdump -pi eth0 port 53 tcpdump: WARNING: eth0: no IPv4 address assigned tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 09:28:46.192113 IP atena.nti.ufpb.br.44510 > rt-dq.quimica.ufpb.br.domain: 43490+ A? rt-dq.quimica.ufpb.br. (39) 09:28:46.193493 IP atena.nti.ufpb.br.48548 > dns-cache-2.bbn.ufpb.br.domain: 13528+ PTR? 1.145.165.150.in-addr.arpa. (44) 09:28:46.193851 IP rt-dq.quimica.ufpb.br.domain > atena.nti.ufpb.br.44510: 43490*- 1/3/0 A 150.165.145.1 (107) 09:28:46.194279 IP dns-cache-2.bbn.ufpb.br.domain > atena.nti.ufpb.br.48548: 13528 1/2/3 PTR rt-dq.quimica.ufpb.br. (198) 09:28:46.194540 IP atena.nti.ufpb.br.41682 > dns-cache-2.bbn.ufpb.br.domain: 33671+ PTR? 13.250.165.150.in-addr.arpa. (45) 09:28:46.195187 IP dns-cache-2.bbn.ufpb.br.domain > atena.nti.ufpb.br.41682: 33671 1/2/3 PTR atena.nti.ufpb.br. (195) 09:28:46.195462 IP atena.nti.ufpb.br.51372 > dns-cache-2.bbn.ufpb.br.domain: 36444+ PTR? 3.255.165.150.in-addr.arpa. (44) 09:28:46.196094 IP dns-cache-2.bbn.ufpb.br.domain > atena.nti.ufpb.br.51372: 36444 1/2/3 PTR dns-cache-2.bbn.ufpb.br. (200) ^C 8 packets captured 10 packets received by filter 0 packets dropped by kernel I also tried with tshark, and got the same 2 packets as when using tcpdum with -w: root@atena:~# tshark -pf "port 53" -i eth0 tshark: Lua: Error during loading: [string "/usr/share/wireshark/init.lua"]:45: dofile has been disabled Running as user "root" and group "root". This could be dangerous. Capturing on eth0 0.000000 150.165.250.13 -> 150.165.145.1 DNS 85 Standard query A rt-dq.quimica.ufpb.br 0.002514 150.165.145.1 -> 150.165.250.13 DNS 153 Standard query response A 150.165.145.1 ^C2 packets captured I tried this MANY times, and always got the same results. Is tcpdump supposed to work like this? _______________________________________________ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
