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This article introduces the relevant knowledge of "sorting out common network commands under Linux". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

You can use any of the following commands:

Nstat command: network statistics tool

Type the following command:

The code is as follows:

# nstat

Sample output:

# kernel

IpInReceives 133243 0.0

IpInDelivers 133243 0.0

IpOutRequests 92904 0.0

IcmpOutErrors 97 0.0

IcmpOutTimeExcds 97 0.0

IcmpMsgOutType3 97 0.0

TcpActiveOpens 538 0.0

TcpEstabResets 56 0.0

TcpInSegs 129837 0.0

TcpOutSegs 89720 0.0

TcpRetransSegs 42 0.0

TcpOutRsts 704 0.0

UdpInDatagrams 3255 0.0

UdpNoPorts 97 0.0

UdpOutDatagrams 3270 0.0

Ip6OutNoRoutes 206 0.0

TcpExtTW 141 0.0

TcpExtDelayedACKs 508 0.0

TcpExtDelayedACKLocked 1 0.0

TcpExtDelayedACKLost 42 0.0

TcpExtTCPHPHits 117659 0.0

TcpExtTCPPureAcks 2158 0.0

TcpExtTCPHPAcks 605 0.0

TcpExtTCPSackRecovery 1 0.0

TcpExtTCPLossUndo 16 0.0

TcpExtTCPSackFailures 4 0.0

TcpExtTCPFastRetrans 1 0.0

TcpExtTCPSlowStartRetrans 3 0.0

TcpExtTCPTimeouts 33 0.0

TcpExtTCPDSACKOldSent 40 0.0

TcpExtTCPDSACKRecv 5 0.0

TcpExtTCPAbortOnData 120 0.0

TcpExtTCPAbortOnClose 55 0.0

TcpExtTCPSackShiftFallback 9 0.0

IpExtInOctets 180131682 0.0

IpExtOutOctets 7289106 0.0

Ss command: query socket tool

To view the statistical summary, enter:

The code is as follows:

# ss-s

Sample output:

Total: 786 (kernel 804)

TCP: 65 (estab 40, closed 7, orphaned 0, synrecv 0, timewait 6max 0), ports 56

Transport Total IP IPv6

* 804--

RAW 1 1 0

UDP 12 9 3

TCP 58 52 6

INET 71 62 9

FRAG 0 0 0

Netstat command: a good old tool for displaying socket information

To view all network ports and summary information table, enter:

The code is as follows:

# netstat-I

Sample output:

Kernel Interface table

Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg

Eth0 1500 0 941022 00 0 688165 00 0 BMRU

Lo 16436 0 9304 0 0 0 9304 0 0 0 LRU

Ppp0 1496 0 3784 0 0 0 4177 0 0 0 MOPRU

To view summary statistics for each protocol, enter:

The code is as follows:

# netstat-s

Sample output:

Ip:

1092065 total packets received

0 forwarded

0 incoming packets discarded

1091681 incoming packets delivered

798913 requests sent out

895 dropped because of missing route

759 reassemblies required

375 packets reassembled ok

Icmp:

17 ICMP messages received

0 input ICMP message failed.

ICMP input histogram:

Timeout in transit: 8

Echo replies: 9

1747 ICMP messages sent

0 ICMP messages failed

ICMP output histogram:

Destination unreachable: 1730

Echo request: 17

IcmpMsg:

InType0: 9

InType11: 8

OutType3: 1730

OutType8: 17

Tcp:

4822 active connections openings

1129 passive connection openings

457 failed connection attempts

165 connection resets received

7 connections established

1062519 segments received

771394 segments send out

7158 segments retransmited

6 bad segments received.

2578 resets sent

Udp:

20846 packets received

1730 packets to unknown port received.

0 packet receive errors

19242 packets sent

UdpLite:

TcpExt:

71 invalid SYN cookies received

8 resets received for embryonic SYN_RECV sockets

142 packets pruned from receive queue because of socket buffer overrun

2109 TCP sockets finished time wait in fast timer

84 packets rejects in established connections because of timestamp

19454 delayed acks sent

6 delayed acks further delayed because of locked socket

Quick ack mode was activated 7306 times

1 packets directly queued to recvmsg prequeue.

1 bytes directly received in process context from prequeue

823921 packet headers predicted

24412 acknowledgments not containing data payload received

10150 predicted acknowledgments

242 times recovered from packet loss by selective acknowledgements

33 congestion windows recovered without slow start by DSACK

335 congestion windows recovered without slow start after partial ack

336 TCP data loss events

TCPLostRetransmit: 35

1 timeouts after reno fast retransmit

156 timeouts after SACK recovery

116 timeouts in loss state

461 fast retransmits

5 forward retransmits

608 retransmits in slow start

2073 other TCP timeouts

62 SACK retransmits failed

43074 packets collapsed in receive queue due to low socket buffer

8499 DSACKs sent for old packets

101 DSACKs sent for out of order packets

308 DSACKs received

9 DSACKs for out of order packets received

427 connections reset due to unexpected data

122 connections reset due to early user close

28 connections aborted due to timeout

TCPDSACKIgnoredOld: 3

TCPDSACKIgnoredNoUndo: 60

TCPSpuriousRTOs: 4

TCPSackShifted: 282

TCPSackMerged: 740

TCPSackShiftFallback: 1017

IpExt:

InMcastPkts: 47

OutMcastPkts: 51

InBcastPkts: 1

InOctets: 1341508973

OutOctets: 72525352

InMcastOctets: 8649

OutMcastOctets: 7519

InBcastOctets: 328

Ip / ifconfig command: configure or display network port information

Type the following command:

The code is as follows:

# ifconfig

Or

The code is as follows:

# / sbin/ifconfig

Or

The code is as follows:

# ifconfig eth0

Eth0 Link encap:Ethernet HWaddr b8:ac:6f:65:31:e5

Inet addr:192.168.1.5 Bcast:192.168.1.255 Mask:255.255.255.0

Inet6 addr: fe80::baac:6fff:fe65:31e5/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:966334 errors:0 dropped:0 overruns:0 frame:0

TX packets:703297 errors:0 dropped:0 overruns:0 carrier:0

Collisions:0 txqueuelen:1000

RX bytes:1186255648 (1.1 GiB) TX bytes:73968238 (70.5 MiB)

Interrupt:17

Lo Link encap:Local Loopback

Inet addr:127.0.0.1 Mask:255.0.0.0

Inet6 addr: 1/128 Scope:Host

UP LOOPBACK RUNNING MTU:16436 Metric:1

RX packets:9666 errors:0 dropped:0 overruns:0 frame:0

TX packets:9666 errors:0 dropped:0 overruns:0 carrier:0

Collisions:0 txqueuelen:0

RX bytes:1399578 (1.3 MiB) TX bytes:1399578 (1.3 MiB)

Ppp0 Link encap:Point-to-Point Protocol

Inet addr:10.1.11.70 P-t-P:10.0.31.18 Mask:255.255.255.255

UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1496 Metric:1

RX packets:3784 errors:0 dropped:0 overruns:0 frame:0

TX packets:4177 errors:0 dropped:0 overruns:0 carrier:0

Collisions:0 txqueuelen:3

RX bytes:2400265 (2.2 MiB) TX bytes:275983 (269.5 KiB)

To display network port statistics, enter:

The code is as follows:

# ip-s link

Sample output:

1: lo: mtu 16436 qdisc noqueue state UNKNOWN

Link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

RX: bytes packets errors dropped overrun mcast

1444187 9960 0 0 0

TX: bytes packets errors dropped carrier collsns

1444187 9960 0 0 0

2: eth0: mtu 1500 qdisc mq state UP qlen 1000

Link/ether b8:ac:6f:65:31:e5 brd ff:ff:ff:ff:ff:ff

RX: bytes packets errors dropped overrun mcast

1221956483 991501 0 0 0 24

TX: bytes packets errors dropped carrier collsns

75623937 720272 0 0 0

3: wlan0: mtu 1500 qdisc noop state DOWN qlen 1000

Link/ether 00:21:6a:ca:9b:10 brd ff:ff:ff:ff:ff:ff

RX: bytes packets errors dropped overrun mcast

0 0 0

TX: bytes packets errors dropped carrier collsns

0 0 0

4: pan0: mtu 1500 qdisc noop state DOWN

Link/ether 4a:c7:5f:0e:8e:d8 brd ff:ff:ff:ff:ff:ff

RX: bytes packets errors dropped overrun mcast

0 0 0

TX: bytes packets errors dropped carrier collsns

0 0 0

8: ppp0: mtu 1496 qdisc pfifo_fast state UNKNOWN qlen 3

Link/ppp

RX: bytes packets errors dropped overrun mcast

2419881 3848 0 0 0

TX: bytes packets errors dropped carrier collsns

284151 4287 0 0 0

Sar command: displaying network statistics

Enter the following command (you need to install and enable sar through the sysstat package):

The code is as follows:

Sar-n DEV

Linux 2.6.32-220.2.1.el6.x86_64 (www.cyberciti.biz) Tuesday 13 March 2012 _ x86 CPU 642)

12:00:01 CDT IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

12:10:01 CDT lo 0.00 0.00 0.00

12:10:01 CDT eth0 127.13 121.32 95.45 18.34 0.00 0.00 0.00

12:10:01 CDT eth2 98.48 110.62 16.72 96.33 0.00 0.00 0.00

12:20:01 CDT lo 0.00 0.00 0.00

12:20:01 CDT eth0 139.95 133.41 106.30 19.95 0.00 0.00 0.00

12:20:01 CDT eth2 110.65 121.85 18.14 107.13 0.00 0.00 0.00

12:30:01 CDT lo 0.00 0.00 0.00

12:30:01 CDT eth0 147.85 132.49 115.78 20.45 0.00 0.00 0.00

12:30:01 CDT eth2 111.88 127.39 18.61 117.65 0.00 0.00 0.00

12:40:01 CDT lo 0.00 0.00 0.00

12:40:01 CDT eth0 136.75 124.64 105.24 19.48 0.00 0.00 0.00

12:40:01 CDT eth2 101.65 115.32 17.58 104.50 0.00 0.00 0.00

12:50:01 CDT lo 0.00 0.00 0.00

12:50:01 CDT eth0 131.45 125.69 96.49 19.58 0.00 0.00 0.00

12:50:01 CDT eth2 101.41 111.31 17.54 96.78 0.00 0.00 0.00

01:00:01 CDT lo 0.00 0.00 0.00

01:00:01 CDT eth0 140.30 133.27 102.17 20.75 0.00 0.00 0.00

01:00:01 CDT eth2 106.90 119.51 18.53 103.09 0.00 0.00 0.00

01:10:01 CDT lo 0.00 0.00 0.00

01:10:01 CDT eth0 152.03 127.74 125.56 19.85 0.00 0.00 0.00

01:10:01 CDT eth2 115.60 134.57 18.73 126.96 0.00 0.00 0.00

01:20:01 CDT lo 0.00 0.00 0.00

01:20:01 CDT eth0 138.55 130.55 103.03 20.20 0.00 0.00 0.00

....

..

....

..

.

01:00:01 CDT eth2 156.82 169.48 28.83 138.49 0.00 0.00 0.00

01:10:01 CDT lo 0.00 0.00 0.00

01:10:01 CDT eth0 215.19 194.82 163.11 30.99 0.00 0.00 0.00

01:10:01 CDT eth2 162.49 183.79 28.36 163.70 0.00 0.00 0.00

01:20:01 CDT lo 0.00 0.00 0.00

01:20:01 CDT eth0 200.20 192.23 140.64 30.93 0.00 0.00 0.00

01:20:01 CDT eth2 153.60 166.96 27.32 140.26 0.00 0.00 0.00

01:30:01 CDT lo 0.00 0.00 0.00

01:30:01 CDT eth0 111.98 103.58 79.12 16.52 0.00 0.00 0.48

01:30:01 CDT eth2 87.50 95.58 14.74 79.35 0.00 0.00 0.00

Average: IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

Average: lo 0.00 0.00 0.00

Average: eth0 211.21 196.20 156.18 31.20 0.00 0.00 0.01

Average: eth2 159.10 174.52 28.00 149.95 0.00 0.00 0.00

Or enter the following command:

The code is as follows:

# sar-n DEV 1 3

Sample output:

Linux 2.6.32-220.2.1.el6.x86_64 (www.cyberciti.biz) Tuesday 13 March 2012 _ x86 CPU 642)

01:44:03 CDT IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

01:44:04 CDT lo 0.00 0.00 0.00

01:44:04 CDT eth0 161.70 154.26 105.20 26.63 0.00 0.00 0.00

01:44:04 CDT eth2 145.74 142.55 25.11 144.94 0.00 0.00 0.00

01:44:04 CDT IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

01:44:05 CDT lo 0.00 0.00 0.00

01:44:05 CDT eth0 162.14 156.31 107.46 42.18 0.00 0.00 0.00

01:44:05 CDT eth2 135.92 138.83 39.38 104.92 0.00 0.00 0.00

01:44:05 CDT IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

01:44:06 CDT lo 0.00 0.00 0.00

01:44:06 CDT eth0 303.92 293.14 272.91 37.40 0.00 0.00 0.00

01:44:06 CDT eth2 252.94 290.20 34.87 263.50 0.00 0.00 0.00

Average: IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s

Average: lo 0.00 0.00 0.00

Average: eth0 210.37 202.34 163.19 35.66 0.00 0.00 0.00

Average: eth2 178.93 191.64 33.36 171.60 0.00 0.00 0.00

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