4.md

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第4节 netstat网络端口查看

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❤️💕💕linux常用的网络命令补充，网络知识的补充，Linux网络编程基础。Myblog:http:https://nsddd.top

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netstat命令

经常用到的是netstat命令，我们需要看对应的端口和进程，经常需要去判断端口和进程是否正常。

root@ubuntu:~# netstat --help
usage: netstat [-vWeenNcCF] [<Af>] -r         netstat {-V|--version|-h|--help}
       netstat [-vWnNcaeol] [<Socket> ...]
       netstat { [-vWeenNac] -i | [-cnNe] -M | -s [-6tuw] }

        -r, --route              display routing table
        -i, --interfaces         display interface table
        -g, --groups             display multicast group memberships
        -s, --statistics         display networking statistics (like SNMP)
        -M, --masquerade         display masqueraded connections

        -v, --verbose            be verbose
        -W, --wide               don't truncate IP addresses
        -n, --numeric            don't resolve names
        --numeric-hosts          don't resolve host names
        --numeric-ports          don't resolve port names
        --numeric-users          don't resolve user names
        -N, --symbolic           resolve hardware names
        -e, --extend             display other/more information
        -p, --programs           display PID/Program name for sockets
        -o, --timers             display timers
        -c, --continuous         continuous listing

        -l, --listening          display listening server sockets
        -a, --all                display all sockets (default: connected)
        -F, --fib                display Forwarding Information Base (default)
        -C, --cache              display routing cache instead of FIB
        -Z, --context            display SELinux security context for sockets

  <Socket>={-t|--tcp} {-u|--udp} {-U|--udplite} {-S|--sctp} {-w|--raw}
           {-x|--unix} --ax25 --ipx --netrom
  <AF>=Use '-6|-4' or '-A <af>' or '--<af>'; default: inet
  List of possible address families (which support routing):
    inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25) 
    netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP) 
    x25 (CCITT X.25) 

查看所有网络连接情况

• a： all显示所有套接字（socket）信息
• n：显示数字地址信息而非主机名

netstat -an

一般来说和管道一起用，因为数据太多了不好找

我们使用nginx，提醒我们80端口被占用

root@ubuntu:~# nginx
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 127.0.0.1:81 failed (98: Address already in use)

查看80端口占用情况

netstat -an | grep 80

浏览器访问80端口

杀死端口

我们要先显示所有端口的信息，筛选出自己需要的端口

• 后面的分别表示为进程ID：进程名
• -t表示TCP
• -u表示UDP
• -l表示正在监听

netstat -tunlp | grep 80	

pkill -9 httpd

本地回环地址和所有的网卡地址

本地回环地址：

用于机器的内部通信，由于机器内部引用通信，外部无法访问地址，每个机器都有自己的127.0.0.1

127.0.0.1

所有的网卡地址：

同时启动所有的IP，用户无论启动哪个IP，都能启动对应业务

0.0.0.0

查看路由表信息

netstat -rn  # 等同于route -n

显示网络接口情况

• Iface：网络设备名
• MIU：最大传输单元（字节）
• RX-OK/TX-OK：正确接收了多少数据包，发送了多少数据包
• ……. ERR：错误
• Flg：标记

netstat -i

查看服务器监听

netstat -tunlp | grep 3306
netstat -tunlp | grep 80
netstat -tunlp | grep 443  # 443是监听HTTPS 服务是否允许
netstat -tunlp | grep 23

ss命令

ss是一个比较新的命令，也是有有很多的参数

root@ubuntu:~# ss --help
Usage: ss [ OPTIONS ]
       ss [ OPTIONS ] [ FILTER ]
   -h, --help          this message
   -V, --version       output version information
   -n, --numeric       don't resolve service names
   -r, --resolve       resolve host names
   -a, --all           display all sockets
   -l, --listening     display listening sockets
   -o, --options       show timer information
   -e, --extended      show detailed socket information
   -m, --memory        show socket memory usage
   -p, --processes     show process using socket
   -i, --info          show internal TCP information
       --tipcinfo      show internal tipc socket information
   -s, --summary       show socket usage summary
       --tos           show tos and priority information
   -b, --bpf           show bpf filter socket information
   -E, --events        continually display sockets as they are destroyed
   -Z, --context       display process SELinux security contexts
   -z, --contexts      display process and socket SELinux security contexts
   -N, --net           switch to the specified network namespace name

   -4, --ipv4          display only IP version 4 sockets
   -6, --ipv6          display only IP version 6 sockets
   -0, --packet        display PACKET sockets
   -t, --tcp           display only TCP sockets
   -S, --sctp          display only SCTP sockets
   -u, --udp           display only UDP sockets
   -d, --dccp          display only DCCP sockets
   -w, --raw           display only RAW sockets
   -x, --unix          display only Unix domain sockets
       --tipc          display only TIPC sockets
       --vsock         display only vsock sockets
   -f, --family=FAMILY display sockets of type FAMILY
       FAMILY := {inet|inet6|link|unix|netlink|vsock|tipc|xdp|help}

   -K, --kill          forcibly close sockets, display what was closed
   -H, --no-header     Suppress header line
   -O, --oneline       socket's data printed on a single line

   -A, --query=QUERY, --socket=QUERY
       QUERY := {all|inet|tcp|udp|raw|unix|unix_dgram|unix_stream|unix_seqpacket|packet|netlink|vsock_stream|vsock_dgram|tipc}[,QUERY]

   -D, --diag=FILE     Dump raw information about TCP sockets to FILE
   -F, --filter=FILE   read filter information from FILE
       FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
       STATE-FILTER := {all|connected|synchronized|bucket|big|TCP-STATES}
         TCP-STATES := {established|syn-sent|syn-recv|fin-wait-{1,2}|time-wait|closed|close-wait|last-ack|listening|closing}
          connected := {established|syn-sent|syn-recv|fin-wait-{1,2}|time-wait|close-wait|last-ack|closing}
       synchronized := {established|syn-recv|fin-wait-{1,2}|time-wait|close-wait|last-ack|closing}
             bucket := {syn-recv|time-wait}
                big := {established|syn-sent|fin-wait-{1,2}|closed|close-wait|last-ack|listening|closing}

显示所有的socket套接字连接情况

ss -an

显示所有正在监听

ss -atulp

END 链接

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