Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #532
Difficulty: Medium
UTF-8 uses a fixed number of bytes to encode characters.
True or False?
Linux & Unix Commands - Search Man Pages

route(8) [bsd man page]

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

NAME
route - manually manipulate the routing tables SYNOPSIS
/sbin/route [ -f ] [ -n ] [ command args ] DESCRIPTION
Route is a program used to manually manipulate the network routing tables. It normally is not needed, as the system routing table manage- ment daemon, routed(8), should tend to this task. Route accepts two commands: add, to add a route, and delete, to delete a route. All commands have the following syntax: /sbin/route command [ net | host ] destination gateway [ metric ] where destination is the destination host or network, gateway is the next-hop gateway to which packets should be addressed, and metric is a count indicating the number of hops to the destination. The metric is required for add commands; it must be zero if the destination is on a directly-attached network, and nonzero if the route utilizes one or more gateways. If adding a route with metric 0, the gateway given is the address of this host on the common network, indicating the interface to be used for transmission. Routes to a particular host are dis- tinguished from those to a network by interpreting the Internet address associated with destination. The optional keywords 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, or if the destination is the symbolic name of a network, then the route is assumed to be to a network; otherwise, it is pre- sumed to be a route to a host. If the route is to a destination connected via a gateway, the metric should be greater than 0. All sym- bolic names specified for a destination or gateway are looked up first as a host name using gethostbyname(3N). If this lookup fails, get- netbyname(3N) is then used to interpret the name as that of a network. Route uses a raw socket and the SIOCADDRT and SIOCDELRT ioctl's to do its work. As such, only the super-user may modify the routing tables. If the -f option is specified, route will ``flush'' the routing tables of all gateway entries. If this is used in conjunction with one of the commands described above, the tables are flushed prior to the command's application. The -n option prevents attempts to print host and network names symbolically when reporting actions. 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 call. If the gateway address used was not the primary address of the gateway (the first one returned by gethostbyname), the gateway address is printed numerically as well as symbolically. ``delete [ host | network ] %s: gateway %s flags %x'' As above, but when deleting an entry. ``%s %s done'' When the -f flag 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
intro(4N), routed(8), XNSrouted(8) 4.2 Berkeley Distribution November 16, 1996 ROUTE(8)

Check Out this Related Man Page

gateways(4)						     Kernel Interfaces Manual						       gateways(4)

NAME
gateways - Specifies Internet routing information to the routed daemon SYNOPSIS
/etc/gateways DESCRIPTION
The /etc/gateways file identifies gateways for the routed daemon. Ordinarily, the routed daemon queries the network and builds routing tables. The routed daemon builds the tables from routing information transmitted by other hosts directly connected to the network. How- ever, there may be gateways that this command cannot identify through its queries. These unidentified gateways are known as distant gate- ways. Such gateways should be identified in the /etc/gateways file, which the routed daemon reads when it starts. The general format of an file entry in the /etc/gateways file is: Destination Name1 gateway Name2 metric Value Type The following is a brief description of each element in an /etc/gateways file entry: A keyword that indicates whether the route is to a network or to a specific host. The two possible keywords are net and host. The name associated with Destination. Name1 can be either a symbolic name (as used in the /etc/hosts or /etc/networks file) or an Internet address specified in dotted-decimal format. An indicator that the following string identifies the gateway host. The name or address of the gateway host to which messages should be forwarded. An indicator that the next string represents the hop count to the destination host or network. The hop count, or number of gateways, from the local network to the destination network. A keyword that indicates whether the gateway should be treated as active, passive, or external. The three possible keywords are as follows: An active gateway is treated like a network interface. That is, it is expected to exchange RIP (Routing Information Protocol) routing information. Information about it is maintained in the internal routing tables as long as it is active and is included in any routing information that is transmitted through RIP. If it does not respond for a period of time, the route associated with it is deleted from the internal routing tables. A passive gateway is not expected to exchange RIP routing information. Information about it is maintained in the routing tables indefinitely and is included in any routing information that is transmitted through RIP. An external gateway is identified to inform the routed daemon that another routing process will install such a route and that alternative routes to that destination should not be installed. Information about external gateways is not maintained in the internal rout- ing tables and is not transmitted through RIP. Note that these routes must be to networks. EXAMPLES
To specify a route to a network through a gateway host with an entry in the gateways file, enter: net net2 gateway host4 metric 4 passive This example specifies a route to a network, net2, through the gateway host4. The hop count metric to net2 is 4, and the gateway is treated as passive. To specify a route to a host through a gateway host with an entry in the gateways file, enter: host host2 gate- way host4 metric 4 passive This example specifies a route to a host, host2, through the gateway host4. The hop count metric to host2 is 4, and the gateway is treated as passive. To specify a route to a host through an active Internet gateway with an entry in the gateways file, enter: host host10 gateway 192.100.11.5 metric 9 active This example specifies a route to a specific host, host10, through the gateway 192.100.11.5. The hop count metric to host10 is 9 and the gateway is treated as active. To specify a route to a host through a passive Internet gateway with an entry in the gateways file, enter: host host10 gateway 192.100.11.5 metric 9 passive This example specifies a route to a specific host, host10, through the gateway 192.100.11.5. The hop metric count to host10 is 9 and the gateway is treated as passive. To specify a route to a network through an external gateway, enter a line in the following format: net net5 gateway host7 metric 11 external This example specifies a route to a network, net5, through the gateway host7. The hop count metric to net5 is 11 and the gateway is treated as external (that is, it is not advertised through RIP, but is advertised through an unspecified routing protocol). RELATED INFORMATION
Daemons: gated(8), routed(8) delim off gateways(4)

Featured Tech Videos