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RISC OS Configuration - Network Address Translation

Protocols and Applications tested and working

Caveats - Network Address translation is simpler, but less featureful than other modes of networking, but will be suitable in almost all circumstances.

Run RPCEmu and open the networking configuration GUI (on the main menu, Settings -> Networking).

rpcemu configure dialog

Select the 'Network Address Translation' option and click on OK. RPCEmu will reset and RISC OS will restart.

We now configure RISC OS to use the network we've just set up.

The IP addresses we use here, remain the same regardless of the host OS configuration and will not need to be changed should the host network change (e.g. wifi etc).

These screenshots are from RISC OS 5.24, other versions of RISC OS will be very similar but not necessarily identical.

Run !Boot, to run the configure app, and click the Network icon:

Click the Internet icon:

Click Enable TCP/IP Protocol Suite, then click the Interfaces icon.

In 'Interfaces' make sure EtherRPCEm is selected and click the Configure... button.

If you are running a version of RISC OS that supports DHCP (RISC OS Select, Adjust, 5 and 6) then you can optionally use that to simplify things, and follow the Blue instructions otherwise you can use a static IP address and use the Yellow instructions.


Choose DHCP; and Click Set.



Choose Manually; and in IP address enter In Netmask enter Click Set.

Click Close on the 'Interfaces' window.

Now click the Routing icon in the 'Internet Configuration' window:

Enter the Gateway as the IP address of the NAT router. Click Set.

Now click the Host names icon in the 'Internet Configuration' window:

DNS configuration: You must enter a value for Host name and Local Domain for RISC OS DNS to work, though the exact values are not important. This example uses the values myhost and domain. Enter Primary name server as the IP address of the RPCEmu NAT DNS server

On RISC OS 5, you may need to click the Try name server too box before several of the boxes become editable.

Click Set on the 'Host names' window.


Click Close on the 'Internet Configuration' window. You will be prompted to reboot RISC OS and must reboot before networking will be available.

Test configuration

Enter these commands at a RISC OS command prompt.

First check that the interface has been created:

ifconfig -a

This should have a rpcem0 interface in the output with the IP address we set earlier,

lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet netmask 0xff000000
        inet netmask 0xffffff00 broadcast
        ether 06:02:03:04:05:06

Next try to ping the router we're using.

ping -c 4

Next try a 'gethost' to test the DNS configuration.

gethost <a website that you know is up right now, eg.>

The results should have the IP address of the site in. E.g.

   type:  2
 length:  4

If this all succeeded then networking has been set up successfully.

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