Where Linux Stores Routing Table Entries on Disk

Linux routing tables exist in kernel memory during runtime. To persist routes across reboots, you need to store them on disk and have them reloaded during system startup. The mechanism varies depending on your network management setup.

systemd-networkd and netplan (modern systems)

On contemporary distributions using systemd-networkd or netplan, define routes in YAML configuration files.

With netplan, create or edit /etc/netplan/01-netcfg.yaml:

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      routes:
        - to: 10.1.1.0/24
          via: 192.168.1.1
          metric: 100
        - to: 10.2.0.0/16
          via: 192.168.1.254

Apply with:

sudo netplan apply

With systemd-networkd, place .network files in /etc/systemd/network/:

[Match]
Name=eth0

[Network]
DHCP=yes

[Route]
Destination=10.1.1.0/24
Gateway=192.168.1.1
Metric=100

[Route]
Destination=10.2.0.0/16
Gateway=192.168.1.254

Reload with:

sudo systemctl restart systemd-networkd

NetworkManager

NetworkManager stores configuration in /etc/NetworkManager/system-connections/ as .nmconnection files. Edit these directly or use the GUI:

nmtui

Or configure routes via nmcli:

nmcli connection modify "connection-name" +ipv4.routes "10.1.1.0/24 192.168.1.1"
nmcli connection up "connection-name"

Legacy: /etc/sysconfig/static-routes (RHEL/CentOS 7 and earlier)

On older RHEL/CentOS systems using traditional init scripts, static routes go in /etc/sysconfig/static-routes:

any host 10.1.1.8 gw 8.9.10.11
any net 10.2.0.0 netmask 255.255.255.0 gw 192.168.1.1

The format is any [net|host] destination [netmask mask] gw gateway. The network script parses lines starting with any and passes them to route add.

Per-interface routes (legacy)

On systems with ifcfg scripts, routes can also be defined in /etc/sysconfig/network-scripts/route-eth0:

10.1.1.0/24 via 192.168.1.1
10.2.0.0/16 via 192.168.1.254 metric 100

Verifying persistent routes

After configuration, verify routes are loaded:

ip route show

Check route configuration is correct:

ip route show table all

To view all route tables:

cat /etc/iproute2/rt_tables

Adding runtime-only routes

For temporary routes that don’t survive reboot, use ip route:

sudo ip route add 10.1.1.0/24 via 192.168.1.1
sudo ip route del 10.1.1.0/24

These disappear after reboot unless persisted through the appropriate configuration method above.

Key differences from iptables

Unlike firewall rules (iptables/nftables), routing table entries aren’t typically stored in a single dedicated dump file like /etc/sysconfig/iptables. Instead, they’re defined as part of network interface configuration, allowing routes to be associated with specific connections and applied conditionally based on network state.