Diff: RoutingHowTo

--- Version 4 

+++ Version 5 

@@ -6,7 +6,7 @@ 

 

 Regardless of the device you are using it needs to have more than one network interface, should be able to forward packets between the interfaces and should allow you to run firewall software and a routing daemon or two. It's probably a good idea to have a dedicated machine between you own stuff and the rest of the world, usual disclaimer here. 

 ! Configuring IP forwarding 

-Most PC based operating systems support ip forwarding but it is usually not turned on. When you have a PC that has more than one network interface any you want to enable routing you need to make some simple configuration changes to get the machine forwarding packets. 

+Most PC based operating systems support ip forwarding but it is usually not turned on. When you have a PC that has more than one network interface and you want to enable routing, you may need to make some simple configuration changes to get the machine forwarding packets between interfaces. 

 

 Often you have the funny situation where the machine you want to act as a router can see other machines on both subnets but machines on one subnet cannot see machines on the other - you need to enable IP forwarding. 

 !! Linux 

@@ -46,17 +46,14 @@ 

   127.0.0.0       *               255.0.0.0       U     0      0        0 lo 

   default         bgenki2         0.0.0.0         UG    0      0        0 eth0 

 

-You can see different types of routing entries. Some are for machines and others are for subnets. The machine entries are fully qualified addresses or a machine name (192.168.1.3 or wailea) while the subnets are those that end in zero (192.168.2.0). Routes to subnets include the IP Address of the gateway that is used to send packets to the subnet. Typicaly you need to add a route to the gateway first them can add the route to the subnet using the previously defined gateway. There are exceptions to this, MAC OS X will add the gateway automatically and has a different command syntax. 

+You can see different types of routing entries. Some are for machines and others are for subnets. The machine entries are fully qualified addresses or a machine name (192.168.1.3 or wailea) while the subnets (in this case) are those that end in zero (192.168.2.0). Routes to subnets include the IP Address of the gateway that is used to send packets to the subnet. Typically you need to add a route to the gateway first, then add the route to the subnet using the previously defined gateway. There are exceptions to this, MAC OS X will add the gateway automatically and has a different command syntax. 

 Alternative commands can access the same information but most likely formatted differently. The raw routing data is maintained by the kernel and is accessed by these commands from ''/proc/net/route''. 

-  /sbin/ip show route 

+  /sbin/ip route (or /sbin/ip r) 

   /bin/netstat -r 

 ! Default route 

 The default route is the route used for all packets that do not match an explicitly defined route. Each device can have only one default route. Each OS will have a slightly different command syntax for creating a route. The same command usually allows you to look at the routing table as well as set routes. This needs to be done as root or a user with the appropriate permissions. 

- 

  || Linux || route add -net default 192.168.1.1 netmask 255.255.255.0 || 

  || BSD   || route add -net default 192.168.1.1 255.255.255.0 || 

- 

- 

 ! Links 

 

 Good description of (http://home.pacific.net.au/~djames.hub/mesh/routing_faq.html routing concepts ) by Damian James at (http://www.itee.uq.edu.au/~mesh/index.html Brismesh )