Tools used to check Linux network communication

ping

Protocol: icmp

It is used when confirming communication at the IP layer. It cannot be used for a server with a policy that does not respond.

ping example.com

Experts use deadman or not.

tcpdump

Protocol: IP layer to application layer

Capture the packet. You should be able to use tshark.

sudo tcpdump -i ens160

nc

Protocol: Transport layer to application layer

It is used to check if the firewall passes.

server

nc -kl 3000

client

nc server.example.com 3000

telnet

Protocols: smtp, http, telnet

It is used to check whether the application or middleware responds.

telnet example.com 80

curl

Protocols: http, ftp, sftp, tftp, ldap, ...

It is used to check whether the application or middleware responds. There are many supported protocols.

curl -si http://example.com/

Frequently used options:

---i You can see the HTTP response header ---k Skip checking SSL certificate ---s Do not output the progress bar (useful when passing by pipe)

Other

nmap, wget, ss(netstat), lsof, ...

Please let us know in the comments.