How to Add Host, Network, and Default Routes in Linux Using the route Command

The article demonstrates configuring Linux routing across different subnets by using the route command to add host, network, and default routes.

Route command syntax

The general form is:

route [add|del] [-net|-host] target [netmask Nm] [gw Gw] [[dev] If]

add : add a routing rule

del : delete a routing rule

-net : target is a network

-host : target is a single host

target : destination network or host

netmask : subnet mask for the destination

gw : gateway through which packets are sent

dev : network interface (e.g., eth0)

1. Adding a host route

To enable host 192.168.2.10 to ping host 192.168.0.8 via router 2, run:

route add -host 192.168.0.8 gw 192.168.2.1 dev eth0

This directs all traffic for 192.168.0.8 through gateway 192.168.2.1. Verify with route -n (or simply route) to see the new entry.

2. Adding a network route

When a host needs to reach an entire subnet (e.g., the 0.0/24 network), adding a single network route is more efficient than adding many host routes. Use:

route add -net 192.168.0.0 netmask 255.255.255.0 gw 192.168.2.1 dev eth0

This tells the system that any destination in 192.168.0.0/24 should be sent to gateway 192.168.2.1. The route table will show the entry with the appropriate netmask.

3. Adding a default route

To forward all traffic destined for networks outside the current subnet, add a default route: route add default gw 192.168.2.1 dev eth0 The default route (Destination 0.0.0.0) ensures that any non‑local traffic is sent to the specified gateway.

Understanding the route table fields

Destination : target network or host; 0.0.0.0 denotes the default gateway.

Gateway : address of the next hop; 0.0.0.0 means the destination is on the same LAN.

Genmask : subnet mask; 255.255.255.255 for a host route, 0.0.0.0 for the default route.

Flags :

U – route is up

G – uses a gateway

H – host route

R – dynamically created (redirect)

D – dynamically installed by a daemon

M – modified by a daemon

! – reject route

Metric : hop count (not used by the Linux kernel).

Ref : reference count (informational only).

Use : number of lookups for this entry.

Iface : network interface name, e.g., eth0.

Deleting routes

To remove a specific host route: route del 192.168.0.8 To delete a network route: route del -net 192.168.0.0/24 gw 192.168.2.1 To delete the default route: route del default After deletion, verify the routing table again to ensure the entry has been removed.