Linux network settings
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View network settings
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Test network connection
- Use network configuration command
- Modify network profile
This article mainly introduces some basic and common Linux network setting commands and some script file configuration steps in Linux.
I. view and test network configuration
1.ifconfig -- View network interface address
Format: ifconfig [network interface name] [ip address] (subnet mask)
[root@lokott ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.68.130 netmask 255.255.255.0 broadcast 192.168.68.255
inet6 fe80::7eb1:2dde:8a54:6927 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
RX packets 3556 bytes 232528 (227.0 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 104 bytes 16400 (16.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 56 bytes 6144 (6.0 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 56 bytes 6144 (6.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:71:37:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@lokott ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.68.130 netmask 255.255.255.0 broadcast 192.168.68.255
inet6 fe80::7eb1:2dde:8a54:6927 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
RX packets 3560 bytes 232768 (227.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 104 bytes 16400 (16.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2.hostname -- view the hostname
Format: hostname
[root@lokott ~]# hostname lokott [root@lokott ~]# cat /etc/hostname lokott [root@lokott ~]# echo "local" > /etc/hostname [root@lokott ~]# cat /etc/hostname local [root@lokott ~]#You need to restart to set successfully. Another way is to use hostnamectl set hostname ^ c [root@lokott ~]#reboot [root@local ~]# hostnamectl set-hostname lokott [root@local ~]# su [root@lokott ~]# For lokott ^ c
3.route - view route entries
-n: digital display (almost the same in CentOS 6 and 7)
[root@lokott ~]# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default gateway 0.0.0.0 UG 100 0 0 ens33 192.168.68.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 [root@lokott ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.68.2 0.0.0.0 UG 100 0 0 ens33 192.168.68.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
4.netstat -- check the network connection
-n serial number
-p port number
-a all service ports
-r display routing table information
-l display network connection and port information in monitoring status
-t tcp
-u udp
[root@lokott ~]# netstat -natp Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1/systemd tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN 1490/dnsmasq tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 941/sshd tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 939/cupsd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1186/master tcp6 0 0 :::111 :::* LISTEN 1/systemd tcp6 0 0 :::22 :::* LISTEN 941/sshd tcp6 0 0 ::1:631 :::* LISTEN 939/cupsd tcp6 0 0 ::1:25 :::* LISTEN 1186/master [root@lokott ~]# netstat -nuap Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name udp 0 0 0.0.0.0:18066 0.0.0.0:* 3935/dhclient udp 0 0 192.168.122.1:53 0.0.0.0:* 1490/dnsmasq udp 0 0 0.0.0.0:67 0.0.0.0:* 1490/dnsmasq udp 0 0 0.0.0.0:68 0.0.0.0:* 3935/dhclient udp 0 0 0.0.0.0:5353 0.0.0.0:* 553/avahi-daemon: r udp 0 0 0.0.0.0:50467 0.0.0.0:* 553/avahi-daemon: r udp6 0 0 :::61206 :::* 3935/dhclient [root@lokott ~]# netstat -r / / same as route Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface default gateway 0.0.0.0 UG 0 0 0 ens33 192.168.68.0 0.0.0.0 255.255.255.0 U 0 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
5.traceroute -- test the network nodes passing from the current host to the target host
[root@lokott ~]# traceroute 127.0.0.1 traceroute to 127.0.0.1 (127.0.0.1), 30 hops max, 60 byte packets 1 localhost (127.0.0.1) 0.030 ms 0.007 ms 0.035 ms [root@lokott ~]# traceroute 192.168.10.11 traceroute to 192.168.10.11 (192.168.10.11), 30 hops max, 60 byte packets 1 gateway (192.168.68.2) 0.154 ms 0.085 ms 0.087 ms 2 * * * 3 * * * 4 * * * 5 * * * 6 * * * 7 *^C [root@lokott ~]#
6.nslookup -- Test DNS domain name resolution
[root@lokott ~]# nslookup www.taobao.com Server: 192.168.68.2 Address: 192.168.68.2#53 Non-authoritative answer: www.taobao.com canonical name = www.taobao.com.danuoyi.tbcache.com. Name: www.taobao.com.danuoyi.tbcache.com Address: 111.3.79.235 Name: www.taobao.com.danuoyi.tbcache.com Address: 111.3.79.234 Name: www.taobao.com.danuoyi.tbcache.com Address: 211.138.124.238
Add: the dos interface of Windows system is also applicable
2. Set the network address parameters
1. Temporary configuration - used when debugging the network
2. Fixed configuration - to change the configuration file, you need to restart the network service or restart the host before it takes effect, which is equivalent to permanent configuration.
7.ifdown and ifup disable and activate network interface
[root@lokott ~]# ifconfig ens33:0 192.168.155.55 / / virtual interface configuration
[root@lokott ~]# ifconfig ens33:0
ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.155.55 netmask 255.255.255.0 broadcast 192.168.155.255
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
[root@lokott ~]# ifconfig ens33:0 down
[root@lokott ~]# ifconfig ens33:0
ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
[root@lokott ~]# ifconfig ens33:0 192.168.155.55
[root@lokott ~]# ifdown ens33:0
//Usage: ifdown < device name >
[root@lokott ~]# ifdown ens33
//Device 'ens33' disconnected successfully.
[root@lokott ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
RX packets 5048 bytes 329861 (322.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 490 bytes 46907 (45.8 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@lokott ~]# ifconfig ens33:0
ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
[root@lokott ~]# ifup ens33
//Connection activated successfully (D-Bus active path / org/freedesktop/NetworkManager/ActiveConnection/6)
[root@lokott ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.68.130 netmask 255.255.255.0 broadcast 192.168.68.255
inet6 fe80::7eb1:2dde:8a54:6927 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
RX packets 5082 bytes 332183 (324.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 514 bytes 50940 (49.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
8.route add and delete static route records
[root@lokott ~]# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default gateway 0.0.0.0 UG 100 0 0 ens33 192.168.68.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 [root@lokott ~]# route add -net 192.168.10.0/24 gw 192.168.122.1 [root@lokott ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.68.2 0.0.0.0 UG 100 0 0 ens33 192.168.10.0 192.168.122.1 255.255.255.0 UG 0 0 0 virbr0 192.168.68.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 [root@lokott ~]# Route del - net 192.168.10.0/24 / / delete route record [root@lokott ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.68.2 0.0.0.0 UG 100 0 0 ens33 192.168.68.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 [root@lokott ~]# route del default gw 192.168.68.2 / / delete the default gateway [root@lokott ~]# route add default gw 192.168.68.2 / / add default gateway
9. Network interface profile
[root@lokott ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens33 TYPE="Ethernet" //Type is Ethernet PROXY_METHOD="none" BROWSER_ONLY="no" BOOTPROTO="dhcp" //Dynamic acquisition DEFROUTE="yes" IPV4_FAILURE_FATAL="no" IPV6INIT="yes" IPV6_AUTOCONF="yes" IPV6_DEFROUTE="yes" IPV6_FAILURE_FATAL="no" IPV6_ADDR_GEN_MODE="stable-privacy" NAME="ens33" //Network card name is ens33 UUID="5785d9d2-2603-4b14-bbfb-d95f6545e260" DEVICE="ens33" //Set the network interface name to ens33 ONBOOT="yes" //Set the network interface to activate when the Linux system starts [root@lokott ~]#
Of course, we can set the static ip address as follows (be sure to restart the network service):
[root@lokott ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
[root@lokott ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="static"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
UUID="5785d9d2-2603-4b14-bbfb-d95f6545e260"
DEVICE="ens33"
ONBOOT="yes"
IPADDR="192.168.68.130"
NETMASK="255.255.255.0"
GATEWAY="192.168.68.2"
[root@lokott ~]# systemctl restart network
[root@lokott ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.68.130 netmask 255.255.255.0 broadcast 192.168.68.255
inet6 fe80::7eb1:2dde:8a54:6927 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:56:d3:4a txqueuelen 1000 (Ethernet)
RX packets 5803 bytes 377581 (368.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 552 bytes 55914 (54.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 168 bytes 16496 (16.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 168 bytes 16496 (16.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:71:37:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@lokott ~]#
10. Domain name resolution profile
1) specify the server address information to provide DNS resolution for this computer
[root@lokott ~]# cat /etc/resolv.conf # Generated by NetworkManager search localdomain nameserver 192.168.68.2 [root@lokott ~]#
2) local host mapping file
[root@lokott ~]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
Generally, the host information that needs to be accessed frequently can be stored here. According to the mapping table here, you can find whether there is a corresponding record, without going to the DNS server for query, so as to improve the speed of Internet access. However, an exception will occur if the error is added.