TShark

TShark

TShark is the terminal based wireshark.

The ultimate tool to sniff network traffic when you have no X. It analyzes the traffic as wireshark does. Great tool!

MySQL traffic

To look on an application server for MySQL traffic you can use this line:

# IFACE=eth0 ; tshark -i ${IFACE} -d tcp.port==3306,mysql -R "eth.addr eq $(ip link show ${IFACE} | awk '$1 ~ /link\/ether/{print $2}')" -T fields -e mysql.query 'port 3306'

The little awk magic selects only pakets which are from our ethernet address on interface IFACE.

Duplicate ACKs

# tshark -i eth1 -Y tcp.analysis.duplicate_ack

Finding TCP problems

# tshark -i eth1 -Y 'expert.message == "Retransmission (suspected)" || expert.message == "Duplicate ACK (#1)" || expert.message == "Out-Of-Order segment"'

Decode SSL Connections

For example show the used TLS-Versions lower than 1.2.

                Supported Version: TLS 1.3 (0x0304)
                Supported Version: TLS 1.2 (0x0303)
                Supported Version: TLS 1.1 (0x0302)
                Supported Version: TLS 1.0 (0x0301)

$ tshark -n -f 'dst port 1812 or dst port 2083' -Y "ssl.handshake.version<0x00000303" -T fields -e ip.src_host -e ip.dst_host -e tcp.dstport -e udp.dstport  -e ssl.handshake.version
192.168.1.87	192.168.1.140	2083				0x00000301
10.155.4.97	192.168.1.141		1812			0x00000301
192.168.1.85	192.168.1.140	2083				0x00000301
...

or for https:

$ tshark -i eth0 -n -f 'dst port 443' -Y "ssl.handshake.version<0x00000303" -T fields -e ip.src_host -e ip.dst_host -e tcp.dstport  -e ssl.handshake.version