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ROUTE(8) FreeBSD System Manager's Manual ROUTE(8) NAME route - manually manipulate the routing tables SYNOPSIS route [-dnqtv] [-T rtable] command [[modifier ...] arg ...] DESCRIPTION At system start, routing tables are initialised and configured by netstart(8). The route utility can be used to view or manually manipulate the network routing tables. Only the superuser may modify the routing tables. 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 rtable Select an alternate routing table to modify or query. The default is to use the current routing table. The current routing table can be displayed with id(1). -t Write routing messages to a fake device (/dev/null) instead of a real routing socket to test route manipulation. -v Print additional details. The commands are as follows: route [-dnqtv] [-T rtable] add [modifier] destination gateway route [-dnqtv] [-T rtable] change [modifier] destination gateway Add a new route, or modify an existing route, to the host or network at destination. gateway is the next-hop intermediary by which packets should be routed. See Address notation and interpretation for more information. A number of modifiers can be used with add and change, and as documented with the other commands: flags Various flags can be set on routes (viewable using show): -blackhole silently discard packets -cloning generates a new route on use -iface destination is directly reachable -llinfo validly translates address to link address -mpath multiple gateways for a destination exist -nostatic pretend route added by kernel or daemon -proto1 sets protocol specific routing flag #1 -proto2 sets protocol specific routing flag #2 -reject emits an ICMP unreachable when matched -static manually added route (default) The -blackhole and -reject flags require a gateway to the loopback interface, either 127.0.0.1 or ::1. [-lock | -lockrest] -expire n [-lock | -lockrest] -mtu n Specify the lifetime for the route (e.g. if generated by a redirect) or the Maximum Transmission Unit (MTU) size for this path, respectively. The value n is locked if preceded by -lock; if preceded by -lockrest all following -expire and -mtu metrics are locked. -host | -net Interpret destination as a host or network, respectively. -ifa address -ifp ifname Where the destination and gateway are not sufficient to specify the route, these modifiers may be used to determine the interface address (-ifa) or name (-ifp). -label label Associate the route with a label. Route labels can be used to attach arbitrary information to a route. -mpath Used 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. -mplslabel -in label -push|-pop|-swap [-out label] For MPLS routes, specify 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 or -swap. The route's gateway can be specified using the -inet or -inet6 modifier before the address. -netmask mask -prefixlen len Used to add subnet routes with the specified netmask. The netmask should be specified after the destination parameter. If no netmask is specified, an implicit one is used for the AF_INET family. The network mask can also be specified as a prefix length, but in that case one of either -inet or -inet6 must also be specified. -priority n Specifies a routing priority. If no priority is specified, the kernel will set a priority depending on the RTF_STATIC flag to either RTP_STATIC or RTP_DEFAULT. Note that priority 1 is reserved for kernel use. route [-dnqtv] [-T rtable] del[ete] destination [-priority n] [gateway] Delete the route to destination. If multiple routes to the destination exist, a specific route must be selected by specifying the priority and/or a gateway. route [-T rtable] exec command [arg ...] Execute a command, forcing the process and its children to use the routing table and appropriate routing domain as specified with the -T rtable option. route [-nqv] [-T rtable] flush [family] [-iface ifname] [-priority n] Delete all gateway entries from the routing table, optionally limited to a specific address family. Routes matching a specific interface or priority can be flushed by using the -iface or -priority modifiers. route [-nv] [-T rtable] get destination [-priority n] [gateway] Display the route to destination. If multiple routes to the destination exist, a specific route may be selected by specifying the priority and/or a gateway. route [-n] [-T rtable] monitor [family] [-iface] Continuously report any changes to the routing information base. The information reported can be limited to a specific address family, a specific routing table using the -T option, or interface specific messages (link state changes) using the -iface modifier. route [-dtv] [-T rtable] nameserver interface [address ...] Broadcast a list of up to five nameserver address proposals to resolvd(8), which is used to update the list of nameservers for the given interface in resolv.conf(5). If no address is given, a request to remove the nameservers for the given interface is sent. route [-nv] [-T rtable] show [family] [-gateway] [-label label] [-priority n] Display the routing table. 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. If -priority is specified, only routes with the specified priority are shown. It may be specified by number or one of local, connected, static, ospf, rip, or bgp. If the priority is negative, then routes that do not match the numeric priority are shown. Within the output of show, the "Flags" column indicates what flags are set on the route. The mapping between letters and flags is: 1 RTF_PROTO1 Protocol specific routing flag #1. 2 RTF_PROTO2 Protocol specific routing flag #2. 3 RTF_PROTO3 Protocol specific routing flag #3. B RTF_BLACKHOLE Just discard packets. b RTF_BROADCAST Correspond to a local broadcast address. C RTF_CLONING Generate new routes on use. c RTF_CLONED Cloned routes (generated from RTF_CLONING). D RTF_DYNAMIC Created dynamically (by redirect). G RTF_GATEWAY Dest requires forwarding by intermediary. H RTF_HOST Host entry (net otherwise). h RTF_CACHED Referenced by gateway route. L RTF_LLINFO Valid protocol to link address translation. l RTF_LOCAL Correspond to a local address. M RTF_MODIFIED Modified dynamically (by redirect). m RTF_MULTICAST Correspond to a multicast address. n RTF_CONNECTED Interface route. P RTF_MPATH Multipath route. R RTF_REJECT Host or net unreachable. S RTF_STATIC Manually added. T RTF_MPLS MPLS route. U RTF_UP Route usable. route [-T rtable] sourceaddr [-ifp ifname | address] Set the preferred source address to address. The source address can be set to the address assigned to interface ifname if -ifp is specified, or reset by setting the address to zero. If no arguments are given, the preferred source addresses are printed. The preferred source address is not used if the destination is on- link or the source address is assigned to a disabled interface. Address notation and interpretation Addresses are assumed to be IPv4 unless they contain a colon, in which case they are treated as IPv6. Alternatively they may be specified as belonging to a particular address family using one of the following modifiers: -inet IPv4 addresses; see ip(4) -inet6 IPv6 addresses; see ip6(4) -link hardware (link-level) addresses -mpls MPLS addresses -sa actual sockaddr data, in hexadecimal format destination is assumed to be a route to a network if any of the following apply: o the -net modifier is used o it is the word "default", equivalent to 0/0 or ::/0 o it is an address with a "/XX" suffix, where XX is the number of bits in the network portion of the address o it specifies the network portion either with -netmask or -prefixlen If destination is a valid IP address or host name, or the -host modifier is used, it is assumed to be a route to a host. All symbolic names specified for a destination or gateway are looked up using gethostbyname(3). FILES /etc/hosts host and network name database /etc/mygate default gateway address EXIT STATUS For commands other than exec, the route utility exits 0 on success, and >0 if an error occurs. For the exec command the route utility exits with the exit status of command if it could be invoked. Otherwise the route utility exits with one of the following values: 1 An invalid command line option was passed to route or setting the routing table failed. 126 command was found but could not be invoked. 127 command could not be found. EXAMPLES Show the current IPv4 routing tables, without attempting to print hostnames symbolically: $ route -n show -inet 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 Add a static inet6(4) route to a host which is on the vio0 interface that is outside your prefix, and use that host as a default gateway, as used by some hosting providers: # route add -inet6 2001:db8:efef::1 -cloning -link -iface vio0 # route add -inet6 default 2001:db8:efef::1 DIAGNOSTICS %s: gateway %s flags %x The specified route is being added to or deleted from the tables. 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 gethostbyname(3), inet_net_pton(3), inet_pton(3), route(4), rtable(4), hosts(5), mygate(5), netstart(8) HISTORY The route command appeared in 4.2BSD. IPv6 support was added by WIDE/KAME project. The -recvpipe, -hopcount, -sendpipe, -ssthresh, -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. FreeBSD 14.1-RELEASE-p8 August 2, 2023 FreeBSD 14.1-RELEASE-p8