Linux Network Management and attribute Command
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.
