1、数据包 “netstat 1″一秒钟累计一次，”netstat 2″两秒钟累计一次。依此类推

2、查看网卡流量：”systat -if 1″每秒钟刷新一次，”systat -if 2″两秒钟刷新一次，依此类推.
3.cd /usr/ports/net/ifstat;make install;make clean;/usr/local/bin/ifstat也可以显示及时流量。

FreeBSD-带宽占用-查看
[1] netstat 1 netstat -i netstat -I vr0 simple way

[2]ports: nload vivid way eg. view vr0--> nload vr0

[3]systat -if 1 nice way

[4]ports:ntop detailed information about bandwidth, esp for monitoring LAN info, but high system resource needed. view through website, eg. http://localhost:3000

[5]ports:mrtg Did not use it

[6]ports:bandwidthd Did not use it

[7]ports:iftop

对ntop印象不错，生成的报表信息比较全，局域网流量监控特别好

systat -vm 1

netstat -n -I rl0 -ib可以查看网卡rl0 的流量

systat -ip 1