route

route [-CFvnNee] [-A family|-4|-6]route [-v] [-A family|-4|-6] add|del [-net|-host] target [netmask mask] [gw gateway] [metric N] [mss M] [window W] [irtt I] [reject] [dev interface]route [-V|--version] [-h|--help]

route displays and manipulates the kernel IP routing table. The kernel uses routing tables to determine where to send network packets based on their destination addresses.Without arguments, route displays the current routing table. The -n flag shows numeric addresses, avoiding DNS lookups and speeding up display.Routes can be added for networks (ranges of addresses) or specific hosts. The default route (0.0.0.0/0 for IPv4) handles traffic that doesn't match any more specific route—typically pointing to the internet gateway.The gateway specified with gw must be directly reachable via an existing route before a new route through it can be added. CIDR prefix notation (e.g., 10.0.0.0/8) is supported for the target, and is equivalent to specifying a target with a netmask.Modern Linux systems prefer ip route from the iproute2 package, but route remains available for compatibility and is familiar to administrators from older systems.

-n

Show numeric addresses instead of resolving hostnames; speeds up display by avoiding DNS lookups

Verbose output

Display routing table in netstat(8) format; use -ee for extended output including MTU, window, and irtt columns

Operate on the kernel routing cache instead of the FIB

Show symbolic network names rather than CIDR notation (opposite of -n)

Operate on IPv4 routes (alias for -A inet)

Operate on IPv6 routes (alias for -A inet6)

Specify address family (e.g., inet, inet6)

Operate on the kernel FIB (Forwarding Information Base) routing table (default)

Display version information

Add a new route

Delete a route

Target is a network address

Target is a single host address

Route packets via the specified gateway; the gateway must already be reachable

Specify the subnet mask for a network route

Force the route to be associated with the specified network interface

Set the metric (priority) for the route; lower values are preferred

Set the TCP Maximum Segment Size (MSS) in bytes for connections using this route

Set the TCP window size in bytes for connections using this route

Set the initial round-trip time in milliseconds (1–12000) used by TCP for this route

Install a blocking route that causes lookups to fail with "Network unreachable"; useful for preventing traffic to specific destinations

Diagnostic flags set by routing daemons to mark dynamic or modified routes; not normally used manually

Destination: Target network or host addressGateway: Next-hop gateway address; `*` means the destination is directly reachable (no gateway needed)Genmask: Subnet mask for the destination; `255.255.255.255` for host routes, `0.0.0.0` for the default routeFlags: Route state flags — U=up, H=host route, G=uses a gateway, R=reinstated, D=dynamically installed, M=modified by routing daemon, A=installed by addrconf, !=reject routeMetric: Distance to the target, typically in hops; lower values are preferred when multiple routes matchRef: Number of references to this route (not used in Linux; always 0)Use: Count of route lookupsIface: Network interface used to send packets on this route

Route changes made with route are not persistent across reboots. Use network configuration files or a network manager (such as NetworkManager or systemd-networkd) for permanent routes.The route command is deprecated in favor of ip route from the iproute2 package, which offers more features and a consistent syntax.The specified gateway must be reachable before adding a route through it; set up a direct route to the gateway first if necessary.Modifying routes requires root privileges. Incorrect routing configuration can cause complete loss of network connectivity.

ip(8), ip-route(8), ifconfig(8), netstat(8), traceroute(8)