RPCEmu - Linux - Networking

Hello,

I’ve just joined this forum to see if anyone can help me with a networking problem. I have RPCEmu 0.8.15 running on XUbuntu. RISC OS 5.22 is up and running in RPCEmu. Following the instructions for Linux IP Tunnelling on the RPCEmu website…

http://www.marutan.net/rpcemu/manual/network.html

…I’ve had success right up to the last hurdle. I can’t get the final test on the final page of the instructions to work I.e:

> Next try to ping a website by name to test the DNS configuration.
> ping -c 4 <a website that you know is up right now, eg. www.marutan.net>

I can ping everything the instructions ask me to ping. I can even ping a website’s server if I know its IP address, but I can’t ping using a domain name. In the ‘Host names’ dialogue, I have entered my router IP address in the ‘Primary name server’ field. I believe I have followed the instructions to the letter, but at the same time, I don’t fully understand what I am doing, so I can’t be sure of anything.

One further observation is that even though I can ping a server if I know its IP address, I can’t get Netsurf to display the server’s default page by entering the same IP address in the Netsurf address bar. Netsurf does not appear to be able to talk to my router at all – unlike the ‘ping’ command?

Any suggestions would be appreciated. Many thanks.

Given everything else running (ping by IP address) I think the only issue might be on the name server config window

http://www.marutan.net/rpcemu/manual/net-ro-tun.html
http://www.marutan.net/rpcemu/manual/i/ro-tun-7.png

You must have a ‘Host Name’
You must have a ‘Local Domain’
You must put your routers IP address in ‘Primary Name Server’
You must click the ‘Use name servers also’

If it’s not one of those 4 being the issues, I’ll try to come up with some more advanced debugging.

Thanks very much for your reply Peter. I can confirm that I have filled out the fields in the ‘Host names’ dialogue as you say.

Following my first post on this forum yesterday, I have shutdown and then restarted my PC and therefore restarted Linux. I have noticed that when I do that, I am unable to PING my router (DNS server) from RISC OS. I am still able to ping the Linux end of the IP tunnel 172.31.0.1

When setting up the Linux IP Tunnelling I issued the following commands (in root mode – I used ‘sudo -i’ before entering the commands) at the terminal precisely as shown (copied and pasted from the RPCEmu networking instructions):

iptables -I FORWARD -m state —state ESTABLISHED,RELATED -j ACCEPT
iptables -t nat -A POSTROUTING —source 172.31.0.0/16 -o eth0 -j MASQUERADE
sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv4.ip_dynaddr=1

After a little investigation, it appears that each time I restart Linux I have to re-enter these commands. Once I do that, I am back to my original position of being able to ping my router (or anything else) from RISC OS provided I use an IP address rather than a domain name.

One further observation is that when I run rpcemu from the Linux command line as follows…

sudo ./rpcemu

…after rpcemu terminates the following error messages appear on the Linux command line:

shm_unlink(/pulse-shm-3094402229) failed: Permission denied
shm_unlink(/pulse-shm-3962433915) failed: Permission denied

Hopefully some of this will be a clue as to what I might be doing wrong.

Many thanks for your help.