Pode ser algo assim:
nc -vz ip.v4.add.ress 80 #Web (Assuming default port)
nc -vz ip.v4.add.ress 22 #SSH (Assuming default port)
nc -vz ip.v4.add.ress 25 #SMTP/POP/IMAP ? (Assuming SMTP default port)
por exemplo:
nc -vz 10.9.6.100 80
Connection to 10.9.6.100 80 port [tcp/http] succeeded!
nc -vz 10.9.6.100 25
nc: connect to 10.9.6.100 port 25 (tcp) failed: Connection refused