ROUTE(8)

ROUTE(8) | System Manager's Manual | ROUTE(8)

# NAME

`route` — manually manipulate the routing tables

# SYNOPSIS

`route` | [`-dfLnqSsTtv`] command [[modifiers] args]

# DESCRIPTION

`route` is a utility used to manually manipulate the network routing tables. Except for setting up the default route, it is normally not needed, as a system routing table management daemon such as routed(8), should tend to this task.

`route` can be used to modify nearly any aspect of the routing policy, except packet forwarding, which can be manipulated through the sysctl(8) command.

The `route` utility supports a limited number of general options, but a rich command language, enabling the user to specify any arbitrary request that could be delivered via the programmatic interface discussed in route(4).

`-d`
  Turn on debugging
`-f`
  Remove all routes (as per `flush`). If used in conjunction with the `add`, `change`, `delete` or `get` commands, `route` removes the routes before performing the command.
`-L`
  Don't show link layer entries in routing table.
`-n`
  Bypasses attempts to print host and network names symbolically when reporting actions. (The process of translating between symbolic names and numerical equivalents can be quite time consuming, and may require correct operation of the network; thus it may be expedient to forgo this, especially when attempting to repair networking operations).
`-q`
  Suppress all output from commands that manipulate the routing table.
`-S`
  Print a space when a flag is missing so that flags are vertically aligned instead of printing the flags that are set as a contiguous string.
`-s`
  (short) Suppresses all output from a `get` command except for the actual gateway that will be used. How the gateway is printed depends on the type of route being looked up.
`-T`
  Show tags in the route display.
`-t`
  Test only, don't perform any actions.
`-v`
  (verbose) Print additional details.

The `route` utility provides several commands:

`add`
  Add a route.
`flush`
  Remove all routes.
`flushall`
  Remove all routes including the default gateway.
`delete`
  Delete a specific route.
`change`
  Change aspects of a route (such as its gateway).
`get`
  Lookup and display the route for a destination.
`show`
  Print out the route table similar to "netstat -r" (see netstat(1)).
`monitor`
  Continuously report any changes to the routing information base, routing lookup misses, or suspected network partitionings.

The monitor command has the syntax

`route` [`-n`] `monitor` [`-c` count]

If count is specified, `route` exits after receiving count routing messages.

The flush command has the syntax

`route` [`-n`] `flush` [family]

If the `flush` command is specified, `route` will ``flush'' the routing tables of all gateway entries. When the address family is specified by any of the `-atalk`, `-inet`, `-inet6`, or `-mpls` modifiers, only routes having destinations with addresses in the delineated family will be manipulated.

The other commands have the following syntax:

`route` [`-n`] command [`-net` | `-host`] destination gateway

where destination is the destination host or network, and gateway is the next-hop intermediary via which packets should be routed. Routes to a particular host may be distinguished from those to a network by interpreting the Internet address specified as the destination argument. The optional modifiers `-net` and `-host` force the destination to be interpreted as a network or a host, respectively. Otherwise, if the destination has a ``local address part'' of `INADDR_ANY`, or if the destination is the symbolic name of a network, then the route is assumed to be to a network; otherwise, it is presumed to be a route to a host. Optionally, the destination can also be specified in the net/bits format.

For example, `128.32` is interpreted as `-host` `128.0.0.32`; `128.32.130` is interpreted as `-host` `128.32.0.130`; `-net` `128.32` is interpreted as `128.32.0.0`; and `-net` `128.32.130` is interpreted as `128.32.130.0`.

The keyword `default` can be used as the destination to set up a default route to a smart gateway. If no other routes match, this default route will be used as a last resort.

If the destination is directly reachable via an interface requiring no intermediary system to act as a gateway, the `-interface` modifier should be specified; the gateway given is the address of this host on the common network, indicating the interface to be used for transmission.

The optional modifiers `-atalk`, and `-link` specify that all subsequent addresses are in the AppleTalk address family, or are specified as link-level addresses in the form described in link_addr(3), and the names must be numeric specifications rather than symbolic names.

The optional modifier `-tag` specifies an address associated with the route. How the address is used is specific to the address family of the destination and the interface used to forward the packet. Currently route tags are consumed only by the mpls(4) stack; therefore `route` assumes that the subsequent addresses are in the MPLS address family. See mpls(4) for examples of setting routes involving MPLS.

The optional `-netmask` qualifier is intended to achieve the effect of an ESIS redirect with the netmask option, or to manually add subnet routes with netmasks different from that of the implied network interface (as would otherwise be communicated using the OSPF or ISIS routing protocols). One specifies an additional ensuing address parameter (to be interpreted as a network mask). The implicit network mask generated in the `AF_INET` case can be overridden by making sure this option follows the destination parameter. `-prefixlen` is also available for similar purpose, in IPv4 and IPv6 case.

Routes have associated flags which influence operation of the protocols when sending to destinations matched by the routes. These flags are displayed using the following ID characters in the routing display and may be set (or sometimes cleared) by indicating the following corresponding modifiers:

ID | Modifier | Flag Bit | Description
`1` | -proto1 | RTF_PROTO1 | set protocol specific flag #1
`2` | -proto2 | RTF_PROTO2 | set protocol specific flag #2
`B` | -blackhole | RTF_BLACKHOLE | discard pkts (during updates)
`` | -noblackhole | ~RTF_BLACKHOLE | clear blackhole flag
`b` |  | RTF_BROADCAST | route represents a broadcast address
`C` | -cloning | RTF_CLONING | (deprecated) same as `-connected`
`` | -nocloning | ~RTF_CLONING | (deprecated) same as `-noconnected`
`C` | -connected | RTF_CONNECTED | treat as a connected route
`` | -noconnected | ~RTF_CONNECTED | stop treating a connected route
`D` |  | RTF_DYNAMIC | created dynamically (redirect)
`G` |  | RTF_GATEWAY | forward to dest by intermediary
`` | -iface | ~RTF_GATEWAY | destination is directly reachable
`H` |  | RTF_HOST | host entry (net otherwise)
`L` |  | RTF_LLDATA | local link, generated by ARP or NDP
`l` |  | RTF_LOCAL | route represents a local address
`M` |  | RTF_MODIFIED | modified dynamically (redirect)
`p` | -proxy | RTF_ANNOUNCE | make entry a link level proxy
`R` | -reject | RTF_REJECT | send ICMP unreachable on match
`` | -noreject | ~RTF_REJECT | clear reject flag
`S` | -static | RTF_STATIC | manually added route
`` | -nostatic | ~RTF_STATIC | pretend route added automatically
`U` |  | RTF_UP | route usable

The optional modifiers `-rtt`, `-rttvar`, `-sendpipe`, `-recvpipe`, `-mtu`, `-hopcount`, `-expire`, and `-ssthresh` provide initial values to quantities maintained in the routing entry by transport level protocols, such as TCP or TP4. These may be individually locked by preceding each such modifier to be locked by the `-lock` meta-modifier, or one can specify that all ensuing metrics may be locked by the `-lockrest` meta-modifier.

In a `change` or `add` command where the destination and gateway are not sufficient to specify the route the `-ifp` or `-ifa` modifiers may be used to determine the interface or interface address.

All symbolic names specified for a destination or gateway are looked up first as a host name using gethostbyname(3). If this lookup fails, getnetbyname(3) is then used to interpret the name as that of a network.

`route` uses a routing socket and the new message types `RTM_ADD`, `RTM_DELETE`, `RTM_GET`, and `RTM_CHANGE`. As such, only the super-user may modify the routing tables.

# EXIT STATUS

The `route` utility exits 0 on success, and >0 if an error occurs. This includes the use of the `get` command to look up a route that is incomplete.

# EXAMPLES

This sets the default route to 192.168.0.1:

`route add default 192.168.0.1`
This shows all routes, without DNS resolution (this is useful if the DNS is not available):
`route -n show`
To install a static route through 10.200.0.1 to reach the network 192.168.1.0/28, use this:
`route add -net 192.168.1.0 -netmask 255.255.255.240 10.200.0.1`

# DIAGNOSTICS

add [host | network ] %s: gateway %s flags %x
  The specified route is being added to the tables. The values printed are from the routing table entry supplied in the ioctl(2) call. If the gateway address used was not the primary address of the gateway (the first one returned by gethostbyname(3)), the gateway address is printed numerically as well as symbolically.
delete [ host | network ] %s: gateway %s flags %x
  As above, but when deleting an entry.
%s %s done
  When the `flush` command is specified, each routing table entry deleted is indicated with a message of this form.
Network is unreachable
  An attempt to add a route failed because the gateway listed was not on a directly-connected network. The next-hop gateway must be given.
not in table
  A delete operation was attempted for an entry which wasn't present in the tables.
routing table overflow
  An add operation was attempted, but the system was low on resources and was unable to allocate memory to create the new entry.
Permission denied
  The attempted operation is privileged. Only root may modify the routing tables. These privileges are enforced by the kernel.

# SEE ALSO

mpls(4), netintro(4), route(4), routed(8), sysctl(8)

# HISTORY

The `route` command appeared in 4.2BSD. IPv6 support was added by WIDE/KAME project.

Since NetBSD 8.0, `-cloned`, `-nocloned`, `-llinfo` and `-xresolve` were obsolete and `-cloning` and `-nocloning` were deprecated. `-connected` and `-noconnected` appeared in NetBSD 8.0.

# BUGS

The first paragraph may have slightly exaggerated routed(8)'s abilities.

Some uses of the `-ifa` or `-ifp` modifiers with the add command will incorrectly fail with a “Network is unreachable” message if there is no default route. See case `RTM_ADD` in sys/net/rtsock.c:route_output for details.

August 29, 2020 | NetBSD 11.0