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

NAME
     route -- manually manipulate the routing tables

SYNOPSIS
     route [-dnqtv] command [[modifiers] args]

DESCRIPTION
     The route utility is used to manually manipulate the network routing tables.  It normally is
     not needed, as a system routing table management daemon, such as routed(8), should tend to
     this task.

     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 program-
     matic interface discussed in route(4).

     The following options are available:

     -d      Run in debug-only mode, i.e., do not actually modify the routing table.

     -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 forget this, especially when attempting to repair networking opera-
	     tions).

     -t      Run in test-only mode.  /dev/null is used instead of a socket.

     -v      (verbose) Print additional details.

     -q      Suppress all output from the add, change, delete, and flush commands.

     The route utility provides the following commands:

     add	 Add a route.
     flush	 Remove all routes.
     delete	 Delete a specific route.
     del	 Another name for the delete command.
     change	 Change aspects of a route (such as its gateway).
     get	 Lookup and display the route for a destination.
     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

     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 may is specified by any of the -osi, -xns, -atalk, -inet6,
     or -inet modifiers, only routes having destinations with addresses in the delineated family
     will be deleted.

     The other commands have the following syntax:

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

     where destination is the destination host or network, 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 argu-
     ment.  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 (0.0.0.0), 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 could 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; -net 128.32.130 is interpreted as
     128.32.130.0; and 192.168.64/20 is interpreted as -net 192.168.64 -netmask 255.255.240.0.

     A destination of default is a synonym for -net 0.0.0.0, which is the default route.

     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 trans-
     mission.  Alternately, if the interface is point to point the name of the interface itself
     may be given, in which case the route remains valid even if the local or remote addresses
     change.

     The optional modifiers -xns, -osi, -atalk, and -link specify that all subsequent addresses
     are in the XNS, OSI, or AppleTalk address families, or are specified as link-level
     addresses, and the names must be numeric specifications rather than symbolic names.

     The optional -netmask modifier is intended to achieve the effect of an OSI 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 inter-
     preted 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.

     For AF_INET6, the -prefixlen qualifier is available instead of the -mask qualifier because
     non-continuous masks are not allowed in IPv6.  For example, -prefixlen 32 specifies network
     mask of ffff:ffff:0000:0000:0000:0000:0000:0000 to be used.  The default value of prefixlen
     is 64 to get along with the aggregatable address.	But 0 is assumed if default is specified.
     Note that the qualifier works only for AF_INET6 address family.

     Routes have associated flags which influence operation of the protocols when sending to des-
     tinations matched by the routes.  These flags may be set (or sometimes cleared) by indicat-
     ing the following corresponding modifiers:

     -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

     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 (as in the ISO case where several interfaces may have the same address), the -ifp
     or -ifa modifiers may be used to determine the interface or interface address.

     The optional -proxy modifier specifies that the RTF_LLINFO routing table entry is the
     ``published (proxy-only)'' ARP entry, as reported by arp(8).

     The optional -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 RTF_CLONING flag set.

     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.

     The route utility 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.

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 symbol-
     ically.

     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 indi-
     cated 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 was not 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.

     gateway uses the same route  A change operation resulted in a route whose gateway uses the
     same route as the one being changed.  The next-hop gateway should be reachable through a
     different route.

SEE ALSO
     netintro(4), route(4), arp(8), IPXrouted(8), routed(8)

HISTORY
     The route utility appeared in 4.2BSD.

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

     Currently, routes with the RTF_BLACKHOLE flag set need to have the gateway set to an
     instance of the lo(4) driver, using the -iface option, for the flag to have any effect;
     unless IP fast forwarding is enabled, in which case the meaning of the flag will always be
     honored.

BSD					 October 2, 2005				      BSD
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