Tcpdump

Docs

• http://www.rationallyparanoid.com/articles/tcpdump.html
• http://bencane.com/2014/10/13/quick-and-practical-reference-for-tcpdump/
• https://hackertarget.com/tcpdump-examples/

Tools

• wireshark

FAQ

Look for ping

tcpdump -i enp1s0 icmp

human readable output

tcpdump -lnX

tcpdump filtering

look for host and port

tcpdump -i ens192 host 192.168.101.3 and tcp port 993

show connections to a certain port

tcpdump -i eth0 tcp dst port 80

tcpdump: NFLOG link-layer type filtering not implemented

Try adding interface (-i)

tcpdump: Mask syntax for networks only

To match a subnet use net instead of host