8.6.29 Network testing basics

Install netkit-ping, traceroute, dnsutils, ipchains (for 2.2 kernel), iptables (for 2.4 kernel), and net-tools packages and:

     $ ping yahoo.com            # check Internet connection
     $ traceroute yahoo.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)