.\" $NetBSD: route.8,v 1.65 2021/01/02 22:02:27 uwe 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 8.4 (Berkeley) 6/1/94 .\" .Dd August 29, 2020 .Dt ROUTE 8 .Os .Sh NAME .Nm route .Nd manually manipulate the routing tables .Sh SYNOPSIS .Nm .Op Fl dfLnqSsTtv .Ar command .Oo .Op Ar modifiers .Ar args .Oc .Sh DESCRIPTION .Nm 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 .Xr routed 8 , should tend to this task. .Pp .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. .Pp The .Nm 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 .Xr route 4 . .Bl -tag -width Ds .It Fl d Turn on debugging .It Fl f Remove all routes (as per .Cm flush ) . If used in conjunction with the .Cm add , .Cm change , .Cm delete or .Cm get commands, .Nm removes the routes before performing the command. .It Fl L Don't show link layer entries in routing table. .It Fl 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). .It Fl q Suppress all output from commands that manipulate the routing table. .It Fl 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. .It Fl s (short) Suppresses all output from a .Cm 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. .It Fl T Show tags in the route display. .It Fl t Test only, don't perform any actions. .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 flushall Remove all routes including the default gateway. .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 monitor command has the syntax .Pp .Bd -filled -offset indent -compact .Nm .Op Fl n .Cm monitor .Op Fl c Ar count .Ed .Pp If .Ar count is specified, .Nm exits after receiving .Ar count routing messages. .Pp The flush command has the syntax .Pp .Bd -filled -offset indent -compact .Nm .Op Fl n .Cm flush .Op Ar family .Ed .Pp If the .Cm flush command is specified, .Nm will ``flush'' the routing tables of all gateway entries. When the address family is specified by any of the .Fl atalk , .Fl inet , .Fl inet6 , or .Fl mpls modifiers, only routes having destinations with addresses in the delineated family will be manipulated. .Pp The other commands have the following syntax: .Pp .Bd -filled -offset indent -compact .Nm .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 force the destination to be interpreted as a network or a host, respectively. Otherwise, if the .Ar destination has a ``local address part'' of .Dv INADDR_ANY , or if the .Ar 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 .Ar destination can also be specified in the .Ar net Ns / Ns Ar bits format. .Pp For example, .Li 128.32 is interpreted as .Fl host Li 128.0.0.32 ; .Li 128.32.130 is interpreted as .Fl host Li 128.32.0.130 ; .Fl net Li 128.32 is interpreted as .Li 128.32.0.0 ; and .Fl net Li 128.32.130 is interpreted as .Li 128.32.130.0 . .Pp The keyword .Cm default can be used as the .Ar destination to set up a default route to a smart .Ar gateway . If no other routes match, this default route will be used as a last resort. .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 modifiers .Fl atalk , and .Fl link specify that all subsequent addresses are in the .Tn AppleTalk address family, or are specified as link-level addresses in the form described in .Xr link_addr 3 , and the names must be numeric specifications rather than symbolic names. .Pp The optional modifier .Fl 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 .Xr mpls 4 stack; therefore .Nm assumes that the subsequent addresses are in the .Tn MPLS address family. See .Xr mpls 4 for examples of setting routes involving MPLS. .Pp The optional .Fl netmask qualifier is intended to achieve the effect of an .Tn 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 .Dv AF_INET case can be overridden by making sure this option follows the destination parameter. .Fl prefixlen is also available for similar purpose, in IPv4 and IPv6 case. .Pp 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: .Bl -column "ID" "xnoblackhole" "xRTF_BLACKHOLE" "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" .It Sy "ID" Ta Sy "Modifier" Ta Sy " Flag Bit" Ta Sy "Description" .It Li 1 Ta -proto1 Ta " RTF_PROTO1" Ta set protocol specific flag #1 .It Li 2 Ta -proto2 Ta " RTF_PROTO2" Ta set protocol specific flag #2 .It Li B Ta -blackhole Ta " RTF_BLACKHOLE" Ta discard pkts (during updates) .It Li " " Ta -noblackhole Ta ~RTF_BLACKHOLE Ta clear blackhole flag .It Li b Ta "" Ta " RTF_BROADCAST" Ta route represents a broadcast address .It Li C Ta -cloning Ta " RTF_CLONING" Ta (deprecated) same as .Fl connected .It Li " " Ta -nocloning Ta ~RTF_CLONING Ta (deprecated) same as .Fl noconnected .It Li C Ta -connected Ta " RTF_CONNECTED" Ta treat as a connected route .It Li " " Ta -noconnected Ta ~RTF_CONNECTED Ta stop treating a connected route .It Li D Ta "" Ta " RTF_DYNAMIC" Ta created dynamically (redirect) .It Li G Ta "" Ta " RTF_GATEWAY" Ta forward to dest by intermediary .It Li " " Ta -iface Ta ~RTF_GATEWAY Ta destination is directly reachable .It Li H Ta "" Ta " RTF_HOST" Ta host entry (net otherwise) .It Li L Ta "" Ta " RTF_LLDATA" Ta local link, generated by ARP or NDP .It Li l Ta "" Ta " RTF_LOCAL" Ta route represents a local address .It Li M Ta "" Ta " RTF_MODIFIED" Ta modified dynamically (redirect) .It Li p Ta -proxy Ta " RTF_ANNOUNCE" Ta make entry a link level proxy .It Li R Ta -reject Ta " RTF_REJECT" Ta send ICMP unreachable on match .It Li " " Ta -noreject Ta ~RTF_REJECT Ta clear reject flag .It Li S Ta -static Ta " RTF_STATIC" Ta manually added route .It Li " " Ta -nostatic Ta ~RTF_STATIC Ta pretend route added automatically .It Li U Ta "" Ta " RTF_UP" Ta route usable .El .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 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 host name using .Xr gethostbyname 3 . If this lookup fails, .Xr getnetbyname 3 is then used to interpret the name as that of a network. .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 super-user may modify the routing tables. .Sh EXIT STATUS .Ex -std route This includes the use of the .Cm get command to look up a route that is incomplete. .Sh EXAMPLES This sets the default route to 192.168.0.1: .Dl route add default 192.168.0.1 This shows all routes, without DNS resolution (this is useful if the DNS is not available): .Dl route -n show To install a static route through 10.200.0.1 to reach the network 192.168.1.0/28, use this: .Dl route add -net 192.168.1.0 -netmask 255.255.255.240 10.200.0.1 .Sh DIAGNOSTICS .Bl -tag -width Ds .It Sy "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 .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 Sy "delete [ host \&| network ] %s: gateway %s flags %x" As above, but when deleting an entry. .It Sy "%s %s done" When the .Cm flush command is specified, each routing table entry deleted is indicated with a message of this form. .It Sy "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 Sy "not in table" A delete operation was attempted for an entry which wasn't present in the tables. .It Sy "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. .It Sy "Permission denied" The attempted operation is privileged. Only root may modify the routing tables. These privileges are enforced by the kernel. .El .Sh SEE ALSO .Xr mpls 4 , .Xr netintro 4 , .Xr route 4 , .Xr routed 8 , .Xr sysctl 8 .Sh HISTORY The .Nm command appeared in .Bx 4.2 . IPv6 support was added by WIDE/KAME project. .Pp Since .Nx 8.0 , .Fl cloned , .Fl nocloned , .Fl llinfo and .Fl xresolve were obsolete and .Fl cloning and .Fl nocloning were deprecated. .Fl connected and .Fl noconnected appeared in .Nx 8.0 . .Sh BUGS The first paragraph may have slightly exaggerated .Xr routed 8 Ns 's abilities. .Pp Some uses of the .Fl ifa or .Fl ifp modifiers with the add command will incorrectly fail with a .Dq Network is unreachable message if there is no default route. See case .Dv RTM_ADD in .Pa sys/net/rtsock.c:route_output for details.