route



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


NAME

     route - manually manipulate the routing tables


SYNOPSIS

     route [-dnqtv] [-T tableid] command [[modifiers] args]


DESCRIPTION

     route 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 ripd(8), ospfd(8), or bgpd(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 enables the user to specify any arbitrary request
     that could be delivered via the programmatic interface discussed in
     route(4).

     The options are as follows:

     -d      Run in debug-only mode, i.e., don't 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 forgo this, especially when attempting to repair
             networking operations.)

     -q      Suppress all output.

     -T tableid
             Select an alternate routing table to modify or query.  Table 0 is
             the default table.

     -t      Write routing messages to a fake device (/dev/null) instead of a
             real routing socket to test route manipulation.

     -v      (verbose) Print additional details.

     The route utility provides the following simple commands:

     route [-T tableid] exec [command ...]
                 Execute a command forcing the process and its children into
                 the routing domain as specified with the -T tableid option.

     route [-nqv] [-T tableid] flush [modifiers]
                 Delete all gateway entries from the routing table.  When the
                 address family is specified by any one of the family
                 modifiers (listed below), only routes having destinations
                 with addresses in the delineated family will be deleted.
                 Also, only routes matching a specific interface or priority
                 can be flushed by using the -iface or -priority modifiers.

     route [-nv] [-T tableid] get [modifiers] address
                 Extract a routing entry from the kernel.  If -gateway is
                 specified, only routes whose gateway are in the same address
                 family as the destination are shown.

     route [-n] monitor [modifiers]
                 Continuously report any changes to the routing information
                 base, routing lookup misses, or suspected network
                 partitionings.

                 When the address family is specified by any one of the family
                 modifiers (listed below), only routes having destinations
                 with addresses in the delineated family will be shown.  If
                 the -iface modifier is used only interface specific messages
                 (link state changes) are shown.

     route [-nv] [-T tableid] show [family] [-gateway] [-label label]
                 Print out the route table similar to "netstat -r" (see
                 netstat(1)).

                 If -gateway is specified, only routes whose gateway are in
                 the same address family as the destination are shown.

                 If -label is specified, only routes with the specified label
                 are shown.

     The other commands relating to adding, changing, or deleting routes have
     the syntax:

     route [-dnqtv] [-T tableid] add [modifiers] destination gateway
     route [-dnqtv] [-T tableid] change [modifiers] destination gateway
     route [-dnqtv] [-T tableid] delete [modifiers] destination gateway

     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 argument.  The optional
     modifiers -net and -host cause the destination to be interpreted as a
     network or a host, respectively.  Otherwise, type is chosen based on the
     following rules:

     The route is assumed to be to a network if any of the following apply to
     destination:

     o   it is the word "default", equivalent to 0/0
     o   it is an IPv4 address with less than 3 dots
     o   it is an IPv4 address with a ``/XX'' suffix (where XX is the number
         of bits in the network portion of the address and is less than 32)
     o   it is an IPv6 address with a ``/XX'' suffix (where XX is the number
         of bits in the network portion of the address and is less than 128)
     o   it is the symbolic name of a network.

     If destination is a valid IP address or host name, it is presumed to be a
     route to a host.

     For example, 192.168.1.1 is interpreted as -host 192.168.1.1 and
     192.168.1 is interpreted as -net 192.168.1.  Note, however, that
     192.168.2.0 will be interpreted as -host 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
     192.168.2.0/24, 192.168.2/24, or alternately 192.168.2.

     If the destination is directly reachable via an interface requiring no
     intermediary system to act as a gateway, the -iface 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.

     To allow addresses to be interpreted as belonging to a particular address
     family (as well as for use in the family arguments to some commands), the
     following modifiers may be used:

     -inet   Internet Protocol version 4 (IPv4) addresses (see ip(4))
     -inet6  Internet Protocol version 6 (IPv6) addresses (see ip6(4))
     -encap  IPsec (see ipsec(4))
     -link   Hardware (link-level) addresses
     -mpls   MPLS addresses
     -sa     Actual sockaddr data, in hexadecimal format

     In the absence of modifiers, an address is assumed to be IPv4, unless
     containing a `:' character, when it is treated as IPv6.

     The optional modifier -link specifies that all subsequent addresses are
     specified as link-level addresses, and the names must be numeric
     specifications rather than symbolic names.

     The optional -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 AF_INET case can be
     overridden by making sure this option follows the destination parameter.
     -prefixlen is also available for a similar purpose, for IPv6/v4.

     A specific routing priority can be specified with the optional -priority
     qualifier.  If no priority is specified the kernel will set a priority
     depending on the RTF_STATIC flag to either RTP_STATIC or RTP_DEFAULT.

     The optional -mpath modifier needs to be specified with the 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 sysctl(8)
     variables net.inet.ip.multipath and net.inet6.ip6.multipath are used to
     control multipath routing.  If set to 1, multiple routes with the same
     priority are used equally; if set to 0, the first route selected will be
     used for subsequent packets to that destination regardless of source.

     When inserting MPLS routes, particular modifiers must be used.  The
     -mplslabel modifier needs to be specified in an ingress LSR to associate
     a particular label to an IPv4/IPv6 route.  The MPLS traffic -in and -out
     modifiers are intended to identify the ingress label and, optionally, the
     outgoing one.  Additionally, one of the following operations must be
     used: -push, -pop and -swap.  Route's nexthop can be specified with the
     modifier -inet.

     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:

     -blackhole    RTF_BLACKHOLE    silently discard pkts (during updates)
     -cloning      RTF_CLONING      generates a new route on use
     -iface        ~RTF_GATEWAY     destination is directly reachable
     -llinfo       RTF_LLINFO       validly translates proto addr to link addr
     -mpath        RTF_MPATH        multiple gateways for a destination exist
     -nostatic     ~RTF_STATIC      pretend route added by kernel or daemon
     -proto1       RTF_PROTO1       set protocol specific routing flag #1
     -proto2       RTF_PROTO2       set protocol specific routing flag #2
     -reject       RTF_REJECT       emit an ICMP unreachable when matched
     -static       RTF_STATIC       manually added route
     -xresolve     RTF_XRESOLVE     emit mesg on use (for external lookup)

     The optional modifiers -expire and -mtu provide initial values to
     quantities maintained in the routing entry by transport level protocols,
     such as TCP (see tcp(4)).  They have the following meanings:

     -expire n    Lifetime for route (e.g., if generated by a redirect).
     -mtu n       Maximum transmission unit (MTU) size for this path.

     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 name or interface address.

     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.

     The optional -label modifier specifies on route addition or modification
     that the route should have the given label associated with it.  Route
     labels can be used to attach arbitrary information to a route.

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

     route uses a routing socket (see route(4)) and the message types RTM_ADD,
     RTM_DELETE, RTM_GET, and RTM_CHANGE.  As such, only the superuser may
     modify the routing tables.


FILES

     /etc/hosts     host name database
     /etc/mygate    default gateway address
     /etc/networks  network name database


EXAMPLES

     Add a static inet(4) route to the 192.168.5.0/24 network via the
     192.168.0.1 gateway:

           # route add -inet 192.168.5.0/24 192.168.0.1

     Amend the inet(4) route to the 192.168.5.0/24 network to use the
     192.168.0.2 gateway:

           # route change -inet 192.168.5.0/24 192.168.0.2

     Delete the inet(4) route to the 192.168.5.0/24 network:

           # route delete -inet 192.168.5.0/24


DIAGNOSTICS

     %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 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.

     %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.


SEE ALSO

     netstat(1), gethostbyname(3), getnetbyname(3), netintro(4), route(4),
     tcp(4), hosts(5), mygate(5), networks(5), bgpd(8), ospfd(8), ripd(8),
     sysctl(8)


HISTORY

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

     The -recvpipe, -hopcount, -sendpipe, -ssthres, -rtt, and -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.


BUGS

     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 route_output() from sys/net/rtsock.c
     for details.

OpenBSD 5.4                      May 27, 2013                      OpenBSD 5.4

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