$NetBSD: route.8,v 1.6 1995/03/18 15:00:13 cgd Exp $
Copyright (c) 1983, 1991, 1993
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
@(#)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 dnqtv .Op Fl T Ar tableid .Ar command .Oo .Op Ar modifiers .Ar args .Oc .Sh DESCRIPTION .Nm is a utility used to manually view and manipulate the network routing tables. Except for setting up the default route, it normally is not needed to manipulate routes, as a system routing table management daemon, such as .Xr routed 8 , .Xr ospfd 8 , or .Xr bgpd 8 , should tend to this task.
p .Nm can be used to modify nearly any aspect of the routing policy, except packet forwarding, which can be manipulated through the .Xr sysctl 8 command.
p 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 .
p The options are as follows: l -tag -width Ds t Fl d Run in debug-only mode, i.e., don't actually modify the routing table. t 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.) t Fl q Suppress all output. t Fl T Ar tableid Select an alternate routing table to modify or query. Table 0 is the default table. t Fl t Write routing messages to a fake device
a ( /dev/null ) instead of a real routing socket to test route manipulation. t Fl v (verbose) Print additional details. .El
p The .Nm utility provides several commands:
p l -tag -width Fl -compact t Cm add Add a route. t Cm change Change aspects of a route (such as its gateway). t Cm delete Delete a specific route. t Cm flush Remove all routes. t Cm get Lookup and display the route for a destination. t Cm monitor Continuously report any changes to the routing information base, routing lookup misses, or suspected network partitionings. t Cm show Print out the route table similar to "netstat -r" (see .Xr netstat 1 ) . .El
p The .Cm get command has the syntax: d -filled -offset indent .Nm route Op Fl nv .Cm get .Op Ar modifiers .Ar address .Ed
p The .Cm flush command has the syntax: d -filled -offset indent .Nm route Op Fl dnqtv .Cm flush .Op Ar family .Ed
p 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 one of the .Ar family modifiers (listed below), only routes having destinations with addresses in the delineated family will be deleted.
p The .Cm monitor command has the syntax: d -filled -offset indent .Nm route Op Fl dn .Cm monitor .Ed
p The .Cm show command has the syntax: d -filled -offset indent .Nm route Op Fl n .Cm show .Op Ar family .Ed
p The other commands have the syntax: d -filled -offset indent .Nm route Op Fl dnqtv .Ar command .Op Ar modifiers .Ar destination gateway Op Ar netmask .Ed
p .Ar destination is the destination host or network, .Ar gateway is the next-hop intermediary via which packets should be routed, and .Ar netmask behaves the same as the argument to the .Fl netmask modifier and is described below. 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:
p The route is assumed to be to a network if any of the following apply to .Ar destination :
p l -bullet -compact t it is the word "default", equivalent to 0/0 t it is an IPv4 address with less than 3 dots t it is an IPv4 address with a .Dq / Ns Em XX suffix (where .Em XX is the number of bits in the network portion of the address and is less than 32) t it is the symbolic name of a network. .El
p If .Ar destination is a valid IP address or host name, it is presumed to be a route to a host.
p If none of the above apply, .Nm prints an error message and exits.
p 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 .
p 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.
p To allow addresses to be interpreted as belonging to a particular address family (as well as for use in the .Ar family arguments to some commands), the following modifiers may be used:
p l -tag -width -inet6 -compact t Fl inet Internet Protocol version 4 (IPv4) addresses (see .Xr ip 4 ) t Fl inet6 Internet Protocol version 6 (IPv6) addresses (see .Xr ip6 4 ) t Fl encap IPsec (see .Xr ipsec 4 ) t Fl ipx Novell's Internet Packet Exchange (IPX) addresses t Fl link Hardware (link-level) addresses t Fl sa Actual .Vt sockaddr data, in hexadecimal format .El
p 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.
p 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 a routing protocol). 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.
p The optional .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). When multiple routes exist for a destination, one route is selected based on the source address of the packet. The .Xr sysctl 8 variables .Va net.inet.ip.multipath and .Va net.inet6.ip6.multipath are used to control multipath routing. If set to 1, multiple routes are used equally; if set to 0, the first route selected will be used for subsequent packets to that destination regardless of source.
p 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: l -column blackhole RTF_BLACKHOLE t Fl blackhole Ta Dv RTF_BLACKHOLE Ta "silently discard pkts (during updates)" t Fl cloning Ta Dv RTF_CLONING Ta "generates a new route on use" t Fl iface Ta Dv ~RTF_GATEWAY Ta "destination is directly reachable" t Fl llinfo Ta Dv RTF_LLINFO Ta "validly translates proto addr to link addr" t Fl mpath Ta Dv RTF_MPATH Ta "multiple gateways for a destination exist" t Fl nostatic Ta Dv ~RTF_STATIC Ta "pretend route added by kernel or daemon" t Fl proto1 Ta Dv RTF_PROTO1 Ta "set protocol specific routing flag #1" t Fl proto2 Ta Dv RTF_PROTO2 Ta "set protocol specific routing flag #2" t Fl reject Ta Dv RTF_REJECT Ta "emit an ICMP unreachable when matched" t Fl static Ta Dv RTF_STATIC Ta "manually added route" t Fl xresolve Ta Dv RTF_XRESOLVE Ta "emit mesg on use (for external lookup)" .El
p The optional modifiers .Fl mtu and .Fl expire provide initial values to quantities maintained in the routing entry by transport level protocols, such as TCP (see .Xr tcp 4 ) . They have the following meanings:
p l -tag -width "-ssthresh n" -compact t Fl expire Ar n Lifetime for route (e.g., if generated by a redirect). t Fl mtu Ar n Maximum transmission unit .Tn ( MTU ) size for this path. .El
p 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.
p 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.
p The optional .Fl genmask modifier specifies that a cloning mask is present. This specifies the mask applied when determining if a child route should be created. It is only applicable to network routes with the .Dv RTF_CLONING flag set.
p The optional .Fl label modifier specifies on route addition or modification that the route should have the given .Em label associated with it. Route labels can be used to attach arbitrary information to a route.
p 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.
p .Nm uses a routing socket (see .Xr route 4 ) and the 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 l -tag -width "/etc/networks" -compact t Pa /etc/hosts host name database t Pa /etc/mygate default gateway address t Pa /etc/networks network name database .El .Sh DIAGNOSTICS l -diag t "%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. t "%s %s done" When the .Cm flush command is specified, each routing table entry deleted is indicated with a message of this form. t "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. t "not in table" A .Cm delete operation was attempted for an entry which wasn't present in the tables. t "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 netstat 1 , .Xr gethostbyname 3 , .Xr getnetbyname 3 , .Xr netintro 4 , .Xr route 4 , .Xr tcp 4 , .Xr hosts 5 , .Xr mygate 5 , .Xr networks 5 , .Xr bgpd 8 , .Xr ospfd 8 , .Xr routed 8 , .Xr sysctl 8 .Sh HISTORY The .Nm command appeared in x 4.2 . IPv6 support was added by WIDE/KAME project.
p The .Fl recvpipe , .Fl hopcount , .Fl sendpipe , .Fl ssthres , .Fl rtt , and .Fl rttvar modifiers used to be used to initialize various quantities in routing table entries. The routing system no longer uses these values and the modifiers exist now only for compatibility with other operating systems. .Sh BUGS The first paragraph may have slightly exaggerated .Xr routed 8 Ns 's abilities.
p 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