A/UX: TCP/IP Routing Via Ethernet and SL/IP (8/94)


I know that A/UX supports the routing of TCP/IP protocols and services between two Ethernet networks when the A/UX system is properly configured and has two Ethernet adapters in it.

I also know that A/UX supports SL/IP connections for providing TCP/IP protocols and services over direct or dial-up serial connections.

Can A/UX support TCP/IP routing between two networks, one via an Ethernet connection, and the other via SL/IP?

Yes, A/UX supports TCP/IP routing among networks. In A/UX, however, the "ipforwarding" parameter was turned off when it is installed, so that a host can't arbitrarily become a gateway.

You can turn the "ipforwarding" parameter back on by doing the following adb (kernel debugger) command:

# adb -w /unix
===> a.out file = /unix (COFF format)
===> cannot open core
===> ready
ipforwarding?D
===> ipforwarding: 0
ipforwarding?W 1
===> ipforwarding: 0x0 = 0x1
$w
$q
===> #

Then restart A/UX so that the change will take effect. You might also want to make the same change to the /etc/install.d/boot.d/bnet_dr file (adb -w bnet_dr) in case you build a new kernel via newconfig at some later date.

If you would rather not restart, do this:

# adb -w -w /unix /dev/kmem
===> a.out file = /unix (COFF format)
===> core file = /dev/kmem
===> ready
ipforwarding/W 1
===> ipforwarding: 0x0 = 0x1
$w
$q

This changes the running kernel (/dev/kmem) without affecting what will happen after the next start. You can do both changes in one session. The "-k" flag is recommended when working on standalone programs such as the kernel (that's why it's named "-k").


Article Change History:
23 Aug 1994 - Reviewed and updated.
30 Apr 1992 - REVIEWED for technical accuracy.

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Published Date: Feb 18, 2012