服務(wù)器后端必會(huì)(2)-Linux網(wǎng)絡(luò)相關(guān)命令

本文最初發(fā)表于我的個(gè)人站點(diǎn)

1. netstat (show network status) 顯示網(wǎng)絡(luò)狀態(tài)

使用: netstat [OPTION]

netstat

不帶任何參數(shù)的情況下，默認(rèn)輸出如下

Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 10.135.140.109:http         ec2-52-221-254-177.ap:15672 SYN_RECV
tcp        0     40 10.135.140.109:opsec-uaa    171.212.208.223:51167       ESTABLISHED
tcp        0      0 10.135.140.109:43963        101.226.68.166:nsesrvr      ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node Path
unix  6      [ ]         DGRAM                    60962  /dev/log
unix  2      [ ]         DGRAM                    49689  @/org/kernel/udev/udevd
unix  2      [ ]         DGRAM                    18148696
unix  2      [ ]         DGRAM                    18143862
unix  3      [ ]         STREAM     CONNECTED     17474862 /usr/local/sa/agent/secubase/secu-tcs-agent-v5.unix

Active Internet connections (w/o servers)

正如字面的意思就是：正在活躍的英特網(wǎng)網(wǎng)絡(luò)連接。也就是當(dāng)前所有連接到本機(jī)器的所有連接狀態(tài) 。

Proto Recv-Q Send-Q Local Address Foreign Address State
協(xié)議類型 接收隊(duì)列 發(fā)送隊(duì)列 本地地址 外部地址 狀態(tài)

  • 協(xié)議類型: 這里會(huì)出現(xiàn) UDP、TCP、SCTP、ICMP 和 IP 協(xié)議 ， 最常見的應(yīng)該就是TCP和UDP

  • 接收隊(duì)列: 一般都是0，表示沒有堆積的數(shù)據(jù)包

  • 發(fā)送隊(duì)列: 一般都是0，表示沒有堆積的數(shù)據(jù)包

  • 本地地址: 一般是在內(nèi)網(wǎng)的地址，也有可能看到localhost或者127.0.0.1

  • 外部地址: 與外部建立連接的外部ip以及端口。

    這里可以看到171.212.208.223這個(gè)地址的用戶通過端口51167,與服務(wù)器的 http(80端口),opsec-uaa建立了連接

  • 狀態(tài)

  • CLOSED -- 初始（無連接）狀態(tài)。

  • LISTEN -- 偵聽狀態(tài)，等待遠(yuǎn)程機(jī)器的連接請(qǐng)求。

  • SYN_SEND -- 在TCP三次握手期間，主動(dòng)連接端發(fā)送了SYN包后，進(jìn)入SYN_SEND狀態(tài)，等待對(duì)方的ACK包。

  • SYN_RECV -- 在TCP三次握手期間，主動(dòng)連接端收到SYN包后，進(jìn)入SYN_RECV狀態(tài)。

  • ESTABLISHED -- 完成TCP三次握手后，主動(dòng)連接端進(jìn)入。

  • ESTABLISHED -- 狀態(tài)。此時(shí)，TCP連接已經(jīng)建立，可以進(jìn)行通信。

  • FIN_WAIT_1 -- 在TCP四次揮手時(shí)，主動(dòng)關(guān)閉端發(fā)送FIN包后，進(jìn)入FIN_WAIT_1狀態(tài)。

  • FIN_WAIT_2 -- 在TCP四次揮手時(shí)，主動(dòng)關(guān)閉端收到ACK包后，進(jìn)入FIN_WAIT_2狀態(tài)。

  • TIME_WAIT -- 在TCP四次揮手時(shí)，主動(dòng)關(guān)閉端發(fā)送了ACK包之后，進(jìn)入TIME_WAIT狀態(tài)，等待最多MSL時(shí)間，讓被動(dòng)關(guān)閉端收到ACK包。

  • CLOSING -- 在TCP四次揮手期間，主動(dòng)關(guān)閉端發(fā)送了FIN包后，沒有收到對(duì)應(yīng)的ACK包，卻收到對(duì)方的FIN包，此時(shí)，進(jìn)入CLOSING狀態(tài)。

  • CLOSE_WAIT -- 在TCP四次揮手期間，被動(dòng)關(guān)閉端收到FIN包后，進(jìn)入CLOSE_WAIT狀態(tài)。

  • LAST_ACK -- 在TCP四次揮手時(shí)，被動(dòng)關(guān)閉端發(fā)送FIN包后，進(jìn)入LAST_ACK狀態(tài)，等待對(duì)方的ACK包。

Active UNIX domain sockets (w/o servers)

Unix系統(tǒng)上的一個(gè)IPC機(jī)制（InterProcess Communication -進(jìn)程間通信）,這里可以簡(jiǎn)單理解為進(jìn)程間通信需要的數(shù)據(jù)管道,由于不用經(jīng)過網(wǎng)絡(luò)，所以程序之間通過這個(gè)數(shù)據(jù)管道交互時(shí)，不需要打包拆包、計(jì)算校驗(yàn)和、維護(hù)序號(hào)和應(yīng)答等,關(guān)于IPC機(jī)制的簡(jiǎn)介，可以看這篇博客:《IPC 機(jī)制簡(jiǎn)介》,如果了解一點(diǎn)C的話，還可以看看這篇 《Linux下的IPC－UNIX Domain Socket》

| Proto | RefCnt | Flags | Type | State | I-Node | Path
| --- | --- | --- | --- | --- | ---
| 協(xié)議類型| 引用次數(shù) | TODO |數(shù)據(jù)傳輸類型 | 連接的狀態(tài) | Linux中的文件標(biāo)識(shí)號(hào) | 使用的路徑

  • 協(xié)議類型: 這里可以看見只有unix,表示這是一個(gè)unix socket

  • 引用次數(shù): 被程序引用的次數(shù)，不同的程序或者同一個(gè)程序中可以使用同一個(gè)管道來交換數(shù)據(jù)。

  • Flags : 未查到，TODO

  • 數(shù)據(jù)傳輸類型:

    byte streams 字節(jié)流
    datagram 數(shù)據(jù)包

  • 連接的狀態(tài): 與上面網(wǎng)絡(luò)Socket的狀態(tài)相同

  • Linux中的文件標(biāo)識(shí)號(hào): Linux的Inode，可以看這篇博客了解 《Linux的inode的理解》

  • 使用的路徑: 顧名思義，就是這個(gè)管道使用的文件路徑

netstat -a (all) 顯示所有網(wǎng)絡(luò)連接狀態(tài)

[root@VM_140_109_centos ~]# netstat -a | more
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 *:http                      *:*                         LISTEN
tcp        0      0 *:opsec-uaa                 *:*                         LISTEN
tcp        0      0 localhost:smtp              *:*                         LISTEN
tcp        0      0 *:terabase                  *:*                         LISTEN
tcp        0      0 10.135.140.109:http         li1598-70.members.lin:39184 TIME_WAIT
tcp        0      0 10.135.140.109:43963        101.226.68.166:nsesrvr      ESTABLISHED
tcp        0     40 10.135.140.109:opsec-uaa    251.78.70.125.broad.cd.:bcs ESTABLISHED
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node Path
unix  2      [ ACC ]     STREAM     LISTENING     60862  public/showq
unix  2      [ ACC ]     STREAM     LISTENING     60866  private/error
unix  2      [ ACC ]     STREAM     LISTENING     60870  private/retry

netstat -n 以數(shù)字形式代替符號(hào)形式的地址

[root@VM_140_109_centos ~]# netstat -n | more
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 10.135.140.109:43963        101.226.68.166:9988         ESTABLISHED
tcp        0     40 10.135.140.109:19191        125.70.78.251:4677          ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node Path
unix  6      [ ]         DGRAM                    60962  /dev/log
unix  2      [ ]         DGRAM                    49689  @/org/kernel/udev/udevd
unix  2      [ ]         DGRAM                    18426269


[root@VM_140_109_centos ~]# netstat -na | more
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN
tcp        0      0 0.0.0.0:19191               0.0.0.0:*                   LISTEN
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN
tcp        0      0 0.0.0.0:4000                0.0.0.0:*                   LISTEN
tcp        0      0 10.135.140.109:43963        101.226.68.166:9988         ESTABLISHED
tcp        0     40 10.135.140.109:19191        125.70.78.251:4677          ESTABLISHED
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node Path
unix  2      [ ACC ]     STREAM     LISTENING     60862  public/showq
unix  2      [ ACC ]     STREAM     LISTENING     60866  private/error
unix  2      [ ACC ]     STREAM     LISTENING     60870  private/retry
unix  2      [ ACC ]     STREAM     LISTENING     60874  private/discard
unix  2      [ ACC ]     STREAM     LISTENING     60878  private/local
unix  2      [ ACC ]     STREAM     LISTENING     60882  private/virtual

netstat -p 程序的名字打印出來

[root@VM_140_109_centos ~]# netstat -p | more
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name
tcp        0      0 10.135.140.109:41434        10.190.93.159:nsesrvr       ESTABLISHED 4919/secu-tcs-agent
tcp        0     40 10.135.140.109:opsec-uaa    182.148.57.124:27584        ESTABLISHED 10865/sshd
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node PID/Program name    Path
unix  6      [ ]         DGRAM                    60962  4674/rsyslogd       /dev/log
unix  2      [ ]         DGRAM                    49689  3680/udevd          @/org/kernel/udev/udevd
unix  2      [ ]         DGRAM                    23386059 10865/sshd
unix  2      [ ]         DGRAM                    23382189 10037/pickup
unix  3      [ ]         STREAM     CONNECTED     20534979 4919/secu-tcs-agent /usr/local/sa/agent/secubase/secu-tcs-agent-v5.unix
unix  3      [ ]         STREAM     CONNECTED     20534978 1930/sap1005
unix  3      [ ]         STREAM     CONNECTED     20534977 4919/secu-tcs-agent /usr/local/sa/agent/secubase/secu-tcs-agent.unix
unix  3      [ ]         STREAM     CONNECTED     20534976 1930/sap1005
unix  3      [ ]         STREAM     CONNECTED     20489154 4919/secu-tcs-agent /usr/local/sa/agent/secubase/secu-tcs-agent.unix
unix  3      [ ]         STREAM     CONNECTED     20489153 24376/sap1004
unix  3      [ ]         STREAM     CONNECTED     17474862 4919/secu-tcs-agent /usr/local/sa/agent/secubase/secu-tcs-agent-v5.unix
unix  3      [ ]         STREAM     CONNECTED     17474861 30420/sap1009

netstat -l 只列出 Listening 狀態(tài)的網(wǎng)絡(luò)連接

[root@VM_140_109_centos ~]# netstat -l | more
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 *:http                      *:*                         LISTEN
tcp        0      0 *:opsec-uaa                 *:*                         LISTEN
tcp        0      0 localhost:smtp              *:*                         LISTEN
tcp        0      0 *:terabase                  *:*                         LISTEN
Active UNIX domain sockets (only servers)
Proto RefCnt Flags       Type       State         I-Node Path
unix  2      [ ACC ]     STREAM     LISTENING     60862  public/showq
unix  2      [ ACC ]     STREAM     LISTENING     60866  private/error
unix  2      [ ACC ]     STREAM     LISTENING     60870  private/retry
unix  2      [ ACC ]     STREAM     LISTENING     60874  private/discard
unix  2      [ ACC ]     STREAM     LISTENING     60878  private/local
unix  2      [ ACC ]     STREAM     LISTENING     60882  private/virtual
unix  2      [ ACC ]     STREAM     LISTENING     60886  private/lmtp
unix  2      [ ACC ]     STREAM     LISTENING     60890  private/anvil
unix  2      [ ACC ]     STREAM     LISTENING     60894  private/scache

netstat [--tcp|-t] 只列出tcp端口 [--udp|-u] 只列出udp端口

  • TCP
[root@VM_140_109_centos ~]# netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 10.135.140.109:41434        10.190.93.159:nsesrvr       ESTABLISHED
tcp        0     40 10.135.140.109:opsec-uaa    182.148.57.124:27584        ESTABLISHED
  • UDP
[root@VM_140_109_centos ~]# netstat -u
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State

可以看到這里沒有udp的連接

netstat -s 顯示每個(gè)協(xié)議的統(tǒng)計(jì)信息

[root@VM_140_109_centos ~]# netstat -s
Ip:
    14150245 total packets received
    2 with invalid addresses
    0 forwarded
    8 with unknown protocol
    0 incoming packets discarded
    11105122 incoming packets delivered
    11088052 requests sent out
    12 reassemblies required
    5 packets reassembled ok
Icmp:
    2012695 ICMP messages received
    3621 input ICMP message failed.
    ICMP input histogram:
        destination unreachable: 4071
        timeout in transit: 135
        redirects: 6
        echo requests: 2008442
        echo replies: 39
        timestamp request: 2
    2212368 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        destination unreachable: 203924
        echo replies: 2008442
        timestamp replies: 2
IcmpMsg:
        InType0: 39
        InType3: 4071
        InType5: 6
        InType8: 2008442
        InType11: 135
        InType13: 2
        OutType0: 2008442
        OutType3: 203924
        OutType14: 2
Tcp:
    1852 active connections openings
    20442 passive connection openings
    5494 failed connection attempts
    661 connection resets received
    2 connections established
    8820870 segments received
    8805804 segments send out
    15430 segments retransmited
    63 bad segments received.
    7878728 resets sent
Udp:
    44596 packets received
    226787 packets to unknown port received.
    45 packet receive errors
    54450 packets sent
UdpLite:
TcpExt:
    359 invalid SYN cookies received
    5486 resets received for embryonic SYN_RECV sockets
    89 ICMP packets dropped because they were out-of-window
    6570 TCP sockets finished time wait in fast timer
    12 packets rejects in established connections because of timestamp
    24366 delayed acks sent
    29 delayed acks further delayed because of locked socket
    Quick ack mode was activated 1867 times
    590 packets directly queued to recvmsg prequeue.
    14240 packets directly received from backlog
    372729 packets directly received from prequeue
    521641 packets header predicted
    208 packets header predicted and directly queued to user
    118812 acknowledgments not containing data received
    255005 predicted acknowledgments
    846 times recovered from packet loss due to SACK data
    Detected reordering 2 times using FACK
    Detected reordering 1 times using SACK
    Detected reordering 22 times using time stamp
    28 congestion windows fully recovered
    86 congestion windows partially recovered using Hoe heuristic
    TCPDSACKUndo: 37
    253 congestion windows recovered after partial ack
    2913 TCP data loss events
    TCPLostRetransmit: 685
    2 timeouts after reno fast retransmit
    163 timeouts after SACK recovery
    537 timeouts in loss state
    4780 fast retransmits
    460 forward retransmits
    6083 retransmits in slow start
    1742 other TCP timeouts
    298 sack retransmits failed
    1690 DSACKs sent for old packets
    455 DSACKs received
    2 DSACKs for out of order packets received
    13 connections reset due to unexpected data
    36 connections reset due to early user close
    134 connections aborted due to timeout
    TCPDSACKIgnoredOld: 1
    TCPDSACKIgnoredNoUndo: 152
    TCPSpuriousRTOs: 8
    TCPSackShifted: 450
    TCPSackMerged: 4580
    TCPSackShiftFallback: 3187
    TCPChallengeACK: 62
    TCPSYNChallenge: 10
IpExt:
    InMcastPkts: 3
    InOctets: 1246493421
    OutOctets: 759134784
    InMcastOctets: 108

2. netstat 常用組合命令

2.1 找出指定程序正在使用的網(wǎng)絡(luò)端口

netstat -anp | grep ssh (找到ssh使用的網(wǎng)路端口)

非root的賬戶，提示如下,需要root權(quán)限

wzy@wzt-dev2-PC:~$ netstat -anp | grep ssh
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)

切換root之后

root@wzt-dev2-PC:/home/wzy# netstat -anp | grep ssh
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      861/sshd
tcp        0  26556 192.168.0.187:22        192.168.0.174:59863     ESTABLISHED 10766/sshd: wzy [pr
tcp        0      0 192.168.0.187:22        192.168.0.115:57336     ESTABLISHED 12838/sshd: wzy [pr
tcp6       0      0 :::22                   :::*                    LISTEN      861/sshd
unix  2      [ ]         DGRAM                    1137722  10766/sshd: wzy [pr
unix  3      [ ]         STREAM     CONNECTED     16016    861/sshd
unix  3      [ ]         STREAM     CONNECTED     1162258  12838/sshd: wzy [pr
unix  2      [ ]         DGRAM                    1162250  12838/sshd: wzy [pr
unix  3      [ ]         STREAM     CONNECTED     1137737  10766/sshd: wzy [pr

netstat -anp | grep mysqld (找到mysqld使用的網(wǎng)路端口)

root@wzt-dev2-PC:/home/wzy# netstat -anp | grep mysqld
tcp6       0      0 :::3306                 :::*                    LISTEN      2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25408     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25406     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:26278     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25554     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25832     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:21390     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:26336     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25864     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:22198     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:26342     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:21350     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:25958     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:26024     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:19907     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.174:59848     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:26280     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:21352     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:20518     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:19904     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.174:59847     ESTABLISHED 2311/mysqld
tcp6       0      0 192.168.0.187:3306      192.168.0.187:19906     ESTABLISHED 2311/mysqld
unix  2      [ ACC ]     STREAM     LISTENING     23752    2311/mysqld         /tmp/mysql.sock

2.1 找出指定端口的網(wǎng)絡(luò)狀態(tài),打印出使用程序

netstat -anpl | grep :8088 (找到使用8088端口的程序)

root@wzt-dev2-PC:/home/wzy# netstat -anpl | grep :8088
tcp        0      0 0.0.0.0:8088            0.0.0.0:*               LISTEN      928/nginx.conf

這里可以看到nginx正在監(jiān)聽8088端口

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