Netzwerktest

$ ping google.com
# check Internet connection

$ traceroute google.com
# trace IP packets

$ ifconfig
# check host config

$ route -n
# check routing config

$ dig [@dns-server.com] host.dom [{amxany}] less
# check host.dom DNS records by dns-server.com for a {amxany} record

$ ipchains -L -n less
# check packet filter (2.2 kernel)

$ iptables -L -n less
# check packet filter (2.4 kernel)

$ netstat -a
# find all open ports

$ netstat -l --inet
# find listening ports

$ netstat -ln --tcp
# find listening TCP ports (numeric)(numeric)