# iftop

一款实时流量监控工具

## 补充说明

iftop命令 是一款实时流量监控工具，监控TCP/IP连接等，缺点就是无报表功能。必须以root身份才能运行。

### 语法

    iftop(选项)

### 选项

    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
       -n                  don't do hostname lookups
       -N                  don't convert port numbers to services
       -p                  run in promiscuous mode (show traffic between other
                           hosts on the same network segment)
       -b                  don't display a bar graph of traffic
       -B                  Display bandwidth in bytes
       -i interface        listen on named interface
       -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
       -m limit            sets the upper limit for the bandwidth scale
       -c config file      specifies an alternative configuration file
       -t                  use text interface without ncurses

       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

### 界面说明

> 第一行为带宽，这里为1Mbit,不是字节哦. 连接列表，最后三列分别是2秒，10秒和40秒的平均流量 `=>` 代表发送
> `<=` 代表接收 最后三行表示发送，接收和全部的流量， 第二列为你运行iftop到目前流量，第三列为高峰值，第四列为平均值。

### 实例

    iftop           # 默认是监控第一块网卡的流量
    iftop -i eth1   # 监控eth1
    iftop -n        # 直接显示IP, 不进行DNS反解析
    iftop -N        # 直接显示连接埠编号, 不显示服务名称
    iftop -F 192.168.1.0/24 or 192.168.1.0/255.255.255.0  # 显示某个网段进出封包流量