TCPdump is a very powerful command line interface packet sniffer.
1. Install tcpdump
Ubuntu
sudo apt-get install tcpdump
Fedora/Centos/Red hat
sudo yum install tcpdump
2. TCPDUMP USE
- To display the Standard TCPdump output:
tcpdump
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
- Network interfaces available for the capture:
tcpdump -D
1.eth1
2.any (Pseudo-device that captures on all interfaces)
3.lo
- Capture the traffic of a particular interface:
tcpdump -i eth0
- To capture the UDP traffic:
tcpdump udp
- To capture the TCP port 80 traffic:
tcpdump port http
- To capture the traffic from a filter stored in a file:
tcpdump -F file_name
To create a file where the filter is configured (here the TCP 80 port)
vim file_name
port 80
- To send the capture output in a file instead of directly on the screen:
tcpdump -w capture.log
- To read a capture file:
tcpdump -r capture.log
- To display the packets having “wordpress.com” as their source or destination address:
tcpdump host wordpress.com
- To display the FTP packets coming from 192.168.1.100 to 192.168.1.2:
tcpdump src 192.168.1.100 and dst 192.168.1.2 and port ftp
- To display the packets content:
tcpdump -A port ftp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on ath0, link-type EN10MB (Ethernet), capture size 96 bytes 20:53:24.872785 IP local.40205 > 192.168.1.2.ftp: S 4155598838:4155598838(0) win 5840 ….g……………….. ………… 20:53:24.879473 IP local.40205 > 192.168.1.2.ftp: . ack 1228937421 win 183 ….g.I@…………. …….. 20:53:24.881654 IP local.40205 > 192.168.1.2.ftp: . ack 43 win 183 ….g.I@…….8….. ……EN 20:53:26.402046 IP local.40205 > 192.168.1.2.ftp: P 0:10(10) ack 43 win 183 ….g.I@……`$….. …=..ENUSER amateur 20:53:26.403802 IP local.40205 > 192.168.1.2.ftp: . ack 76 win 183 ….h.I@…………. …>..E^ 20:53:29.169036 IP local.40205 > 192.168.1.2.ftp: P 10:25(15) ack 76 win 183 ….h.I@……#c….. ……E^PASS test123 20:53:29.171553 IP local.40205 > 192.168.1.2.ftp: . ack 96 win 183 ….h.I@.,……….. ……Ez 20:53:29.171649 IP local.40205 > 192.168.1.2.ftp: P 25:31(6) ack 96 win 183 ….h.I@.,……….. ……EzSYST 20:53:29.211607 IP local.40205 > 192.168.1.2.ftp: . ack 115 win 183 ….h.I@.?…..j….. ……Ez 20:53:31.367619 IP local.40205 > 192.168.1.2.ftp: P 31:37(6) ack 115 win 183 ….h.I@.?……….. ……EzQUIT 20:53:31.369316 IP local.40205 > 192.168.1.2.ftp: . ack 155 win 183 ….h.I@.g……….. ……E. 20:53:31.369759 IP local.40205 > 192.168.1.2.ftp: F 37:37(0) ack 156 win 183 ….h.I@.h…..e….. ……E.
Packets capture during a FTP connection. The FTP password can be easily intercepted because it is sent in clear text to the server.
We see in this capture the FTP username (amateur) and password (hosting).
You can use this incase you forget your ftp password and have stored it in your ftp client
Please note that this should not be used for any illegal and this blog will not be responsible for any actions that lead to illegal use
