Network testing basics

Network testing basics

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

     $ 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)