14. Configuring PPP for IPX support.

New versions of the pppd PPP daemon for Linux have support thatallows you to carry IPX packets across a PPP serial link. You need at leastversion ppp-2.2.0d of the daemon. See the PPP-HOWTOfor details on where to find it. When you compile pppd you mustensure you enable the IPX support by adding the following two lines:

IPX_CHANGE = 1USE_MS_DNS = 1

to: /usr/src/linux/pppd-2.2.0f/pppd/Makefile.linux.

The IPX_CHANGE is what configures the IPX support into PPP.The USE_MS_DNS define allows Microsoft Windows95 machines to doName Lookups.

The real trick to getting it to work in knowing how to configure it.

There are many ways of doing this, but I'm only going to describe the two thatI've received any information on. I've tried neither yet, so consider thissection experimental, and if you get something to work, please let me know.

14.1 Configuring an IPX/PPP server.

The first thing you need to do is configure your Linux machine as an IP/PPPserver. Don't panic! This isn't difficult. Again, follow the instructions inthe PPP-HOWTO and you should be prettymuch ok. When you have this done there are a couple of simple modificationsyou need to make to get IPX working over the same configuration.

First steps.

One of the first steps you must take is to configure your linux machine as anIPX router as described in the appropriate section earlier in this document.You won't need to use the ipx_route command for the ppp interfacebecause pppd will configure these for you as it does for IP. When youhave the ipxd daemon running it will automatically detect any new IPXinterfaces and propogates routes for them. In this way your dialup hosts willbe seen by other machines automatically when they connect.

Design.

When you are running as a server it will normally be your responsibilityto assign network address to each of the PPP links when they are established.This is an important point, each PPP link will be an IPX network and will havea unique IPX network address. This means that you must decide how you willallocate addresses and what what they will be. A simple convention is toallocate one IPX network address to each serial device that will supportIPX/PPP. You could allocate IPX network addresses based on the login idof the connecting user, but I don't see any particularly good reason to doso.

I will assume that this is what you have done, and that there are two serialdevices (modems) that we will use. The addresses I've assigned in thiscontrived example are:

device IPX Network Address------ -------------------ttyS0  0xABCDEF00ttyS1  0xABCDEF01

Configure pppd.

Configure your /etc/ppp/options.ttyS0 file as follows:

ipx-network 0xABCDEF00ipx-node 2:0ipxcp-accept-remote

and your /etc/ppp/options.ttyS1 file as:

ipx-network 0xABCDEF01ipx-node 3:0ipxcp-accept-remote    

These will ask pppd to allocate the appropriate IPX network addressesto the link when the link is established, set the local node number to2 or 3 and will let the remote node overwrite what theremote node number with what it thinks it is. Note that each of the addressesare hexadecimal numbers and that 0x is required at the start of thenetwork address, but not required at the start of the node address.

There are other places this information could be configured. If you have onlyone dialin modem then an entry could go into the /etc/ppp/optionsfile. Alternatively this information can be passed on the command line topppd.

Test the server configuration.

To test the configuration you will need to have a client configuration thatis known to work. When the caller dials in, logs in and pppd startsit will assign the network address, advise the client of the servers nodenumber and negotiate the clients node number. When this has completed, andafter ipxd has detected the new interface the client should be ableto establish IPX connections to remote hosts.

14.2 Configuring an IPX/PPP client.

In a client configuration, whether or not you configure your Linux machineas an IPX router depends on whether you have a local LAN that you wish toact as an IPX router for. If you are a standalone machine connecting to anIPX/PPP dialin server then you won't need to run ipxd, but if youhave a LAN and wish all of the machines on the LAN to make use of theIPX/PPP route then you must configure and run ipxd as described.This configuration is much simpler because you do not have multiple serialdevices to configure.

Configuring pppd

The simplest configuration is one that allows the server to supply all ofthe IPX network configuration information. This configuration would becompatible with the server configuration described above.

Again you need to add some options to your /etc/ppp/options file,they are:

ipxcp-accept-networkipxcp-accept-remoteipxcp-accept-local

These options tell pppd to act completely passively and acceptall of the configuration details from the server. You could supply defaultvalues here for servers that don't supply details by addingipx-network and ipx-node entries similar to the serverconfiguration.

Testing the IPX/PPP client.

To test the client you will need a known working server to dial into. Afteryou have dialled in and pppd has run you should see the IPX details configuredon your ppp0 device when you run the ifconfig command andyou should be able to use ncpmount.

I'm not sure whether you will have to manually add IPX routes so that youcan reach distant fileserver or not. This seems likely. If anyone runningthis configuration could tell me I'd be grateful.