path: root/sbin/route/route.8

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.\"	@(#)route.8	8.3 (Berkeley) 3/19/94
.\"
.Dd March 19, 1994
.Dt ROUTE 8
.Os
.Sh NAME
.Nm route
.Nd manually manipulate the routing tables
.Sh SYNOPSIS
.Nm route
.Op Fl dnqSv
.Ar command
.Oo
.Op Ar modifiers
.Ar args
.Oc
.Sh DESCRIPTION
.Nm
is a utility used to manually manipulate the network routing tables.
It normally is not needed, as a
system routing table management daemon, such as
.Xr routed 8 ,
should tend to this task.
.Pp
The
.Nm
utility supports a limited number of general options,
but a rich command language enables the user to specify
any arbitrary request that could be delivered via the
programmatic interface discussed in
.Xr route 4 .
.Bl -tag -width Ds
.It Fl d
Run in debug-only mode, i.e., don't actually modify the routing table.
.It Fl n
Bypass 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.)
.It Fl q
Suppress all output.
.It Fl S
Make the
.Cm show
command display the source selector part of the routes.
.It Fl v
(verbose) Print additional details.
.El
.Pp
The
.Nm
utility provides several commands:
.Pp
.Bl -tag -width Fl -compact
.It Cm add
Add a route.
.It Cm flush
Remove all routes.
.It Cm delete
Delete a specific route.
.It Cm change
Change aspects of a route (such as its gateway).
.It Cm get
Lookup and display the route for a destination.
.It Cm show
Print out the route table similar to "netstat -r" (see
.Xr netstat 1 ) .
.It Cm monitor
Continuously report any changes to the routing information base,
routing lookup misses, or suspected network partitionings.
.El
.Pp
The
.Cm monitor
command has the syntax
.Bd -filled -offset indent
.Nm route Op Fl n
.Cm monitor
.Ed
.Pp
The
.Cm flush
command has the syntax
.Bd -filled -offset indent
.Nm route Op Fl n
.Cm flush
.Op Ar family
.Ed
.Pp
If the
.Cm flush
command is specified,
.Nm
will
.Dq flush
the routing tables of all gateway entries.
When the address family is specified by any of the
.Fl ipx ,
.Fl link ,
.Fl x25 ,
.Fl inet ,
or
.Fl inet6
modifiers, only routes having destinations with addresses in the
delineated family will be deleted.
.Pp
The other commands have the following syntax:
.Bd -filled -offset indent
.Nm route Op Fl n
.Ar command
.Op Fl net No \&| Fl host
.Ar destination gateway
.Ed
.Pp
where
.Ar destination
is the destination host or network and
.Ar 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
.Ar destination
argument.
The optional modifiers
.Fl net
and
.Fl host
cause the destination to be interpreted as a network or a host, respectively.
Otherwise, type is chosen based on the following rules:
.Pp
The route is assumed to be to a network if any of the following apply to
.Ar destination :
.Bl -bullet -compact
.It
it is the word "default", equivalent to 0/0
.It
it is an IPv4 address with less than 3 dots
.It
it is an IPv4 address with a
.Dq /XX
suffix (where XX is the number of bits in the network portion of the address
and is less than 32)
.It
it is the symbolic name of a network.
.El
.Pp
If
.Ar destination
is a valid IP address or host name it is presumed to be a route to a host.
.Pp
If none of the above apply,
.Nm
prints an error message and exits.
.Pp
For example,
.Li 192.168.1.1
is interpreted as
.Fl host Li 192.168.1.1
and
.Li 192.168.1
is interpreted as
.Fl net Li 192.168.1 .
Note, however, that
.Li 192.168.2.0
will be interpreted as
.Fl host Li 192.168.2.0
since it is a complete IP address with 3 dots.
In this case the number of bits in the network portion of the address must
be explicitly listed, for example
.Li 192.168.2.0/24 ,
.Li 192.168.2/24
or alternately
.Li 192.168.2 .
.Pp
If the destination is directly reachable
via an interface requiring
no intermediary system to act as a gateway, the
.Fl 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.
.Pp
The optional modifier
.Fl link
specifies that all subsequent addresses are specified as link-level addresses,
and the names must be numeric specifications rather than
symbolic names.
.Pp
The optional
.Fl netmask
qualifier is intended 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
.Dv AF_INET
case
can be overridden by making sure this option follows the
.Ar destination
parameter.
.Fl prefixlen
is also available for a similar purpose, for IPv6/v4.
.Pp
The
.Fl mpath
modifier needs to be specified with the
.Cm add
command to be able to enter multiple gateways for the same destination address
(multipath).
.Pp
Routes have associated flags which influence operation of the protocols
when sending to destinations matched by the routes.
These flags may be set (or sometimes cleared)
by indicating the following corresponding modifiers:
.Bd -literal
-cloning   RTF_CLONING    - generates a new route on use
-xresolve  RTF_XRESOLVE   - emit mesg on use (for external lookup)
-iface    ~RTF_GATEWAY    - destination is directly reachable
-static    RTF_STATIC     - manually added route
-nostatic ~RTF_STATIC     - pretend route added by kernel or daemon
-reject    RTF_REJECT     - emit an ICMP unreachable when matched
-blackhole RTF_BLACKHOLE  - silently discard pkts (during updates)
-proto1    RTF_PROTO1     - set protocol specific routing flag #1
-proto2    RTF_PROTO2     - set protocol specific routing flag #2
-llinfo    RTF_LLINFO     - validly translates proto addr to link addr
.Ed
.Pp
The optional modifiers
.Fl rtt ,
.Fl rttvar ,
.Fl sendpipe ,
.Fl recvpipe ,
.Fl mtu ,
.Fl hopcount ,
.Fl expire ,
and
.Fl 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
.Fl lock
meta-modifier, or one can
specify that all ensuing metrics may be locked by the
.Fl lockrest
meta-modifier.
.Pp
The
.Fl src
and
.Fl srcmask
modifiers can be used to specify the source selector of the route,
which will match the source IP address of outgoing packets.
.Fl src
and
.Fl srcmask
work in a similar way to
.Fl dst
and
.Fl netmask .
For example:
.Bd -literal -offset indent
# route add -src 180.83.46.98 180.83.46.97
# route add -src 192.168.10/24 -dst 10.5.1/24 180.83.46.97
.Ed
.Pp
In a
.Cm change
or
.Cm add
command where the destination and gateway are not sufficient to specify
the route, the
.Fl ifp
or
.Fl ifa
modifiers may be used to determine the interface or interface address.
.Pp
All symbolic names specified for a
.Ar destination
or
.Ar gateway
are looked up first as a network name using
.Xr getnetbyname 3 .
If this lookup fails,
.Xr gethostbyname 3
is then used to interpret the name as a valid host name.
.Pp
.Nm
uses a routing socket and the new message types
.Dv RTM_ADD ,
.Dv RTM_DELETE ,
.Dv RTM_GET ,
and
.Dv RTM_CHANGE .
As such, only the superuser may modify
the routing tables.
.Sh FILES
.Bl -tag -width "/etc/mygate" -compact
.It Pa /etc/mygate
Default gateway address.
.El
.Sh DIAGNOSTICS
.Bl -diag
.It "%s: gateway %s flags %x"
The specified route is being added to or deleted from the tables.
The values printed are from the routing table entry supplied in the
.Xr ioctl 2
call.
If the gateway address used was not the primary address of the gateway
(the first one returned by
.Xr gethostbyname 3 ) ,
the gateway address is printed numerically as well as symbolically.
.It "%s %s done"
When the
.Cm flush
command is specified, each routing table entry deleted
is indicated with a message of this form.
.It "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.
.It "not in table"
A
.Cm delete
operation was attempted for an entry which
wasn't present in the tables.
.It "routing table overflow"
An
.Cm add
operation was attempted, but the system was
low on resources and was unable to allocate memory
to create the new entry.
.El
.Sh SEE ALSO
.Xr esis 4 ,
.Xr netintro 4 ,
.Xr route 4 ,
.Xr mygate 5 ,
.Xr routed 8
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .
IPv6 support was added by WIDE/KAME project.
.Sh BUGS
The first paragraph may have slightly exaggerated
.Xr routed Ns 's
abilities.
.Pp
Some uses of the
.Fl ifa
or
.Fl ifp
modifiers with the
.Cm add
command will incorrectly fail with a
.Dq Network is unreachable
message if there is no default route.
See case
.Dv RTM_ADD
in
.Fn route_output
from
.Pa sys/net/rtsock.c
for details.