Install netkit-ping, traceroute, dnsutils, ipchains (for 2.2 kernel), iptables (for 2.4 kernel), and net-tools packages and:
$ ping google.com # check Internet connection $ traceroute google.com # trace IP packets $ nslookup google.com # to check the name server hostname and server ip details $ ifconfig # check host config $ route -n # check routing config $ dig [@dns-server.com] host.dom [{a|mx|any}] |less # check host.dom DNS records by dns-server.com # for a {a|mx|any} 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)
afzal khan linux talk 