Shulou(Shulou.com)06/01 Report--

I. Linux network management commands

1.Ifconfig command

Ifconfig displays current network information

Format: ifconfig [INTERFACE]

Common options:

-a: view all information

Ifconfig IFACE up | down enabled | disable the interface of a network card

Ifconfig interface [aftype] options | address...

# ifconfig IFACE IP/mask [up]

# ifconfig IFACE IP netmask MASK

Enable promiscuous mode: [-] promisc

Note: takes effect immediately after it is enabled. It will not take effect again when it is turned on again!

Eg: disable the eth2 interface

[root@localhost ~] # ifconfig eth2 down [root@localhost ~] # ifconfig / / you can see that eth2 no longer shows eth0 Link encap:Ethernet HWaddr 00:0C:29:7B:65:71 inet addr:172.16.249.202 Bcast:172.16.255.255 Mask:255.255.0.0 inet6 addr: fe80::20c:29ff:fe7b:6571/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:159414 errors:0 dropped:0 overruns:0 frame:0 TX packets:4673 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:12952278 (12.3 MiB) TX bytes:666573 (650.9 KiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: :: 116128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0b) TX bytes:0 (0.0b)

2.Route command

Common options:

-n: view routing table information

Format: route add | del [- net |-host] target [netmask Nm] [gw Gw] [[dev] If]

Add | del

-net: add | Delete a network route (i.e. add a network segment)

-host: add | Delete a host route

-gw: add | Delete gateway

-netmask: add | Delete subnet mask

Default: add | Delete default route

Eg1: add a host route to eth0 that is 192.168.1.3 and the default gateway is 172.16.0.1

[root@localhost ~] # route add-host 192.168.1.3 gw 172.16.0.1 dev eth0 [root@localhost ~] # route-nKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface192.168.1.3 172.16.0.1 255.255.255.255 UGH 000 eth0192.168.27.0 0.0.0.0 255.255.255.0 U 00 0 eth2169.254.0.0 0.0.0.0 255.255.0.0 U 1002 00 eth0169.254.0.0 0.0.0.0 255.255.0.0 U 1003 00 eth2172.16.0.0 0.0.0.0 255.255.0.0 U 00 eth00.0.0.0 172.16.0.1 0.0.0.0 UG 000 eth0 delete 192.168.1.3 this route [root@localhost ~] # route del-host 192.168.1.3 [root@localhost ~] # route-nKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface192.168.27.0 0.0.0.0 255.255.255.0 U 00 0 eth2169.254.0.0 0.0.0.0 255.255.0.0 U 1002 00 eth0169.254.0.0 0.0.0.0 255.255.0.0 U 1003 00 eth2172.16.0.0 0.0 .0.0 255.255.0.0 U 00 eth00.0.0.0 172.16.0.1 0.0.0.0 UG 00 eth0 [root@localhost ~] # Delete this routing entry [root@localhost ~] # route del-net 192.168.0.0amp24 [root@localhost ~] # route-nKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface192.168.27.0 0.0.0.0 255.255.255.0 U 00 0 eth2169.254.0.0 0.0.0.0 255.255.0.0 U 1002 00 eth0169.254.0.0 0.0.0.0 255.255.0.0 U 1003 00 eth2172.16.0.0 0.0.0.0 255.255.0.0 U 00 eth00.0.0.0 172.16.0.1 0.0.0 UG 00 eth0 or [root@localhost ~] # route del-net 192.168.0.0 netmask 255.255.255. 0 Eg2: add a network route to the eth0 interface as 192.168.0.0. The default gateway is 172.16.0.1 [root@localhost ~] # route add-net 192.168.0.0 netmask 255.255.255.0 gw 172.16.0.1 dev eth0 [root@localhost ~] # route add-net 192.168.0.0 dev eth0 24 gw 172.16.0.1 dev eth0

3.Netstat command

1 >. Show network connections:

Format: netstat [--tcp |-t] [--udp |-- raw |-w] [--listening |-l] [--all |-a] [--numeric |-- numeric-hosts] [--numeric-ports] [--numeric-ports] [--symbolic |-N] [--extend |-e [--extend |-e]]

Common options:

-t: related to tcp protocol

-u: related to udp protocol

-l: listening sockets / / often followed by the-tfurowu option

-p: print information

-e: extended information

-n: display in digital form

-p: displays relevant pid information

Eg: digitally shows which ports the tcp protocol listens on the current host and prints out [root@chang ~] # netstat-tnlpActive Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0 0 root@chang 22 0 0 0 * LISTEN 1821/sshd tcp 0 0127.0.0.1 LISTEN 2181/sshd tcp 631 0.0.0.0 LISTEN 2181/sshd tcp * LISTEN 1612/cupsd tcp 0 0127.0.0.1 LISTEN 2181/sshd tcp 0 0 0 LISTEN 1478/rpcbind tcp 50982 0 0 0 LISTEN 1580/rpc.statd tcp 0 0 0 15 0 0 0:: 22 : * LISTEN 1821/sshd tcp 0 0:: 1 LISTEN 631: * LISTEN 1612/cupsd tcp 0 0:: 1:25 1935/master tcp 0 0: 35321: * LISTEN 1580/rpc.statd tcp 0 0:: 1 LISTEN 2181/sshd tcp 0 0 10: 111 :: * LISTEN 1478/rpcbind

2 >. Display routing information

Format: netstat {--route |-r} [--numeric |-n] [--numeric-hosts] [--numeric-ports] [--numeric-ports]

Common options:

-r: displays the kernel routing table

-n: display in digital format

3 >. Display interface statistics

Netstat {--interfaces |-I |-I} [iface] [- all |-a] [--extend |-e] [--program |-p]

Common options:

-I: displays all interface information

-I IFACE: displays multi-specified interface information

II. Linux Network Properties Command

1.Ip command

Format: ip [OPTIONS] OBJECT {COMMAND | help}

OBJECT: = {link | addr | route}

Ip link-network device configuration

Set DEVICE {up | down} Activation | disable an API

Show DEVICE

Show up: only interfaces that are active are displayed

Ip address-protocol address management

Ip addr {add | del} IFADDR dev STRING

[label LABEL]: indicates the alias of the network card when adding an address

[scope {global | link | host}]: indicates the scope

Global: globally available

Link: only links are available

Host: available locally

Ip address show-look at protocol addresses

[dev DEVICE]

[label PATTERN]

[primary and secondary]

Ip address flush-flush protocol addresses

Use the same format as show

Ip route-routing table management

Ip route add

Add Route: ip route add TARGET via GW dev IFACE src SOURCE_IP

TARGET:

Host routing: IP

Network routing: NETWORK/MASK

Add Gateway: ip route add defalt via GW dev IFACE

Ip route delete

Delete route: ip route del TARGET

Ip route show

Ip route flush

[dev IFACE]

[via PREFIX]

2.ss command

Format: ss [options] [FILTER]

Common options:

-t: related to tcp protocol

-u: related to udp protocol

-w: display bare sockets

-x: unix sock related

-l: connection for listening statu

-a: all

-n: display in digital format

-p: related programs and their pid

-e: information about extend

-m: memory usage

-o: timer information

FILTER: = [state TCP-STATE] [EXPRESSION]

EXPRESSION:

Dport =

Sport =

Supplement: common status of tcp

LISTEN: monitoring

EATABLISHED: established connection

FIN_WAIT_1

FIN_WAIT_2

SYN_SENT

SYN_RECV

CLOSE

The ss command is similar to the netstat command, but it is better to use the ss command when the current number of connections is large.

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