Linux route delete all routes

How to remove all default gateways

I’m running a custom built Linux machine, so not all Linux commands are available.
I execute network related commands, so I need to set a default gateway right before I run my command, then remove that gateway immediately afterward. To do that I run all my commands in one line:

/sbin/route add default gw 10.10.10.10;my command;/sbin/route del default gw 10.10.10.10; 

The problem is, for some reason I once found 2 default gateways on the same machine which caused all my commands to fail because even if I set my default gateway before running my test, it is still messed up and can’t run my test. So is there a way to remove ALL default gateways in one command ? I have a large amount of machines that are increasing and it won’t be practical to plant a script on every machine. I need a command as simple as the following:

/sbin/route del all default;set my default gw;mycommand;/sbin/route del all default; 

All I have found so far is a command to remove a default gateway but not all of them /sbin/route del default which won’t work for me. /sbin/route help displays the following

/sbin/route --help Usage: route [] Edit the kernel's routing tables Options: -n Don't resolve names -e Display other/more information -A inet Select address family 

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How to Add and Delete Static Route in Linux using IP Command

Part of the skill set for any Linux user, and particularly a systems administrator, is the ability to perform some network tweaks on a Linux system. This includes adding and deleting routes to enable the system to communicate with other systems o a local network. In this guide, we explore exactly how you can go about adding and deleting routes on a Linux system.

Viewing the existing routing table

Before we embark on adding or deleting routes, it’s prudent to check the existing default routes on a system. To do so, simply launch your terminal and issue the command:

$ ip route show Or $ ip route list

Similar statistics can be displayed using route command,

Also, you can use the good old netstat command, which is usually used for printing interface statistics as well as the routing table to achieve the same result.

With the default routing statistics in mind, let’s now move a step further and add some routes to our system.

Adding a static route using IP command

Suppose you want to take a backup of a Linux machine and push the backup file to another backup server in the subnet 10.0.2.0/24 . However, for one reason or the other, you cannot reach the backup server via the default gateway. In this case, you will have to create a new route for backup server subnet via another IP, say 192.168.43.223 via the interface enp0s3 .

The command for this will be

$ sudo ip route add 10.0.2.0/24 via 192.168.43.223 dev enp0s3

• 10.0.2.0 -> is the network you want to connect to
• /24 -> is the subnet mask
• 192.168.43.223 -> is the IP through which we will reach the server
• enp0s3 -> is the network interface

You can confirm whether new static route add been in route table using “ip route show” command.

To add the specific IP of the backup server, say 10.0.2.15 run the command:

$ sudo ip route add 10.0.2.15 via 192.168.43.223 dev enp0s3

Once again, you can check the routing changes to see if the changes exist using the ip route show command:

Permanently adding static route (RHEL, Fedora, CentOS)

The routes we have just added are temporary and will not survive a reboot. To make the routes persistent, you need to manually add them.

In the /etc/sysconfig/network-scripts/ directory, create an interface file route-interface where the interface attribute is your network interface name. In our case, this will be route-enp0s3 .

$ vim /etc/sysconfig/network-scripts/route-enps03

Next, we will add the routes as shown:

10.0.2.0/32 via 192.168.43.1 10.0.2.15 via 192.168.43.1

Save the file and exit. Then restart NetworkManager Service

$ sudo systemctl restart NetworkManager

Permanently adding static route (Ubuntu / Debian)

For Debian distributions, edit the file /etc/network/interfaces

$ sudo vim /etc/network/interfaces

Append the following line:

up route add -net 10.0.2.0 netmask 255.255.255.0 gw 192.168.43.1 dev enp0s3

Save and exit the file. Finally, for the changes to come into effect, run below commands

$ sudo ifdown enp0s3 && sudo ifup enp0s3

Deleting a static route

To delete a specific route, use the ip route del command. For example, to remove the route address we just added, run the command:

$ sudo ip route del 10.0.2.0/24 via 192.168.43.223 dev enp0s3

To delete a single IP route in a subnet run the command

$ sudo ip route del 10.0.2.15 via 192.168.43.223 dev enp0s3

To delete default route run:

$ sudo ip route del default

To add a default route run below ‘ip route add’ command,

$ sudo ip route add default via dev interface

$ sudo ip route add default via 192.168.43.1 dev eth0

We hope that this tutorial was informative and provided you with insights into how you can go about adding and deleting static route in Linux.

Also Read : 12 ip Command Examples for Linux Users

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ip route del does not delete entire table

I have recently started using ip route commands for advanced routing stuff. Now I have come across something rather puzzling to me. A default route added to a table will be easily deleted whereas another route remains. I add these two rules:

ip route add dev wlan0 default via 192.168.0.1 table 21 ip route add dev wlan0 192.168.0.0/24 table 21 

default via 192.168.0.1 dev wlan0 192.168.0.0/24 dev wlan0 scope link 

ip route del table 21 ip route show table 21 

192.168.0.0/24 dev wlan0 scope link 

Can anyone explain this? The man page says that del is designed to delete a ROUTE, which also includes tables.

2 Answers 2

As @user3291010 has already pointed out, to delete a full table, use the following command:

This command deletes table 21:

The command you tried is used to remove specific rules from a table. It wants a prefix to match on. When you didn’t supply the prefix, it just deleted the first entry, which happened to be the default route.

To remove the second entry, and only the second entry, you could run this command:

ip route delete table 21 192.168.0.0/24 

As far as I know, there is no way to delete all entries using the delete command.

Syntax to delete individual entries is not clear either. The syntax ip route delete 192.168.1.3/24 only deleted some of the entries before starting to output RTNETLINK answers: No such process which presumably means everything is clear, however executing ip r show table local still shows more like these broadcast 192.168.1.255 dev ens160 table local proto kernel scope link src 192.168.1.3 and local 192.168.1.3 dev ens160 table local proto kernel scope host src 192.168.1.3 . Dozens of experiments reveal no working syntax to remove these. man ip-route doesn’t help either.

Okay, found working syntax with an AI: it is a ip route delete broadcast 192.168.1.255 dev ens160 table local proto kernel scope link src 192.168.1.3 (probably may be shortened) and ip r delete table local local 192.168.1.3 dev ens160 accordingly.

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