最近需要查看下Linux的端口和网络连接状态，找了一些工具尝试了下，发现iftop比较好用，这里简单的笔记下使用方法。

首先看下iftop的帮助命令

cstriker1407@cstriker1407-x64:~$ sudo iftop -h
iftop: display bandwidth usage on an interface by host

Synopsis: iftop -h | [-npblNBP] [-i interface] [-f filter code]
                               [-F net/mask] [-G net6/mask6]

   -h                  display this message   #显示当前信息
   -n                  don't do hostname lookups #不进行hostname反向查询，如果指定了，IP不会显示为已经解析的hostname
   -N                  don't convert port numbers to services #不进行端口反向查询，如果指定了，端口不会显示为指定的名称
   -p                  run in promiscuous mode (show traffic between other
                       hosts on the same network segment)
   -b                  don't display a bar graph of traffic #不显示流量柱状图
   -B                  Display bandwidth in bytes
   -i interface        listen on named interface  #指定监听网卡
   -f filter code      use filter code to select packets to count
                       (default: none, but only IP packets are counted)
   -F net/mask         show traffic flows in/out of IPv4 network
   -G net6/mask6       show traffic flows in/out of IPv6 network
   -l                  display and count link-local IPv6 traffic (default: off)
   -P                  show ports as well as hosts #显示端口
   -m limit            sets the upper limit for the bandwidth scale
   -c config file      specifies an alternative configuration file
   -t                  use text interface without ncurses  #使用正常的text输出模式，不使用ncurses方式，即每次都会刷新console

   Sorting orders:
   -o 2s                Sort by first column (2s traffic average)
   -o 10s               Sort by second column (10s traffic average) [default]
   -o 40s               Sort by third column (40s traffic average)
   -o source            Sort by source address
   -o destination       Sort by destination address

   The following options are only available in combination with -t
   -s num              print one single text output afer num seconds, then quit
   -L num              number of lines to print

iftop, version 1.0pre4
copyright (c) 2002 Paul Warren <pdw@ex-parrot.com> and contributors

这里笔记几个常用的命令

直接最简单方式查看

cstriker1407@cstriker1407-x64:~$ sudo iftop -i wlan0 #此时会使用ncurses方式进行交互式查询

cstriker1407@cstriker1407-x64:~$ sudo iftop -i wlan0 -nNPt
#当需要明确的网络使用情况时，作者比较喜欢这种方式：text方式，显示端口和IP,而且不进行反向查询。

 CentOS如何安装iftop

yum install epel-release
yum install iftop