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)
