useful network utility tools

1. tcpdump
tcpdump -n port 80 -i eth0|lo
monitor all package transferred on 80 port on the network interface eth0/lo
2. netstat
netstat -anp|grep java
trace all network traffic on the process named java
netstat -anp|grep 128.224.159.xxx
trace all network traffic on the host whose ip address is 128.224.159.xxx
3. nslookup
nslookup 206.191.52.46
look up the domain name whose ip address is 206.191.52.46