How to add a static route in rhel7 and rhel7

How to add a static route in rhel7 and rhel7
1. Use the route command to add

// Route entry to the host

[root@localhost ~]# route add -host 8.8.8.8 dev ens3[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens38.8.8.8         0.0.0.0         255.255.255.255 UH    0      0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0[root@localhost ~]# route add -host 8.8.8.8 gw 8.8.8.8[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens38.8.8.8         8.8.8.8         255.255.255.255 UGH   0      0        0 ens38.8.8.8         0.0.0.0         255.255.255.255 UH    0      0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

// Route (why) added to the network)

route add –net 11.11.1.11 netmask 255.255.255.0 dev eth0route add –net 11.11.1.11 netmask 255.255.255.0 gw 11.11.1.1route add –net 11.11.1.0/24 dev eth1

// Add a default gateway

[root@localhost ~]# route add default gw 172.25.8.250[root@localhost ~]# route add default gw 172.25.8.251[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.251    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens38.8.8.8         8.8.8.8         255.255.255.255 UGH   0      0        0 ens38.8.8.8         0.0.0.0         255.255.255.255 UH    0      0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

// Delete a route

[root@localhost ~]# route del -host 8.8.8.8 dev ens3[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.251    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

// After the machine is restarted or the NIC is restarted, the route becomes invalid.

[root@localhost ~]# systemctl restart network[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

2. Use ip commands to add or delete routes

[root@localhost ~]# ip route add default via 172.25.8.251 dev ens3[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.251    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0[root@localhost ~]# ip route add 172.16.1.0/24 via 172.25.8.251 dev ens3[root@localhost ~]# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         172.25.8.251    0.0.0.0         UG    0      0        0 ens30.0.0.0         172.25.8.250    0.0.0.0         UG    100    0        0 ens3172.16.1.0      172.25.8.251    255.255.255.0   UG    0      0        0 ens3172.25.0.0      0.0.0.0         255.255.0.0     U     100    0        0 ens3192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

3. How to set a permanent route in linux

(1) adding it to the end of/etc/sysconfig/network takes effect globally. (Effective method)

GATEWAY = gw-ip or GATEWAY = gw-dev

2) Add a route under/etc/sysconfig/network-script/route-interface (each interface has one file. If no file exists, you can only add a route for this interface)

For example, add a default gateway to eth0:

Vim/etc/sysconfig/network-scripts/ifcfg-eth0 # Add the following content (dev eth0 can be omitted) GATEWAY = X. x. x. X # Save and exit the service network restart or systemctl restart network.