How to use local network (+ XDMCP) and PPP at the same time?

[theYinYeti]

I've got a problem. I used to be happy with networking: there was only PPP and it worked OK. Then I bought a cheap laptop to use as a remote display (X terminal) via XDMCP.

So now I have:

- local network (up by default) with main PC and laptop,

- PPP (down by default, I use kppp) on the main PC.

 

When the laptop is connected to main PC via XDMCP, and I bring PPP up, then the local network connexion is broken and XDMCP freezes.

 

Of course, 127.0.0.X is routed to loopback.

On local network, main PC is 10.0.0.1 and laptop is 10.0.0.2, and 10.0.0.X is routed to eth0.

On PPP, IP is dynamic, DNS is dynamic, and ppp0 becomes default route when PPP is up.

 

As I see it, when ppp0 becomes default route, it should not be a problem with local network because 10.0.0.X is still routed to eth0. Still, as soon as ppp0 is up, local network freezes (the XDMCP-displayed screen on the laptop becomes still, and no more light-blinking can be seen on the ethernet-switch).

 

Any idea?

 

Yves.

[b]

Allo

 

My .02 read is that your kernel is setup and used to 1 only tcpip connection

it now has 2 and does not know how to route them correctly

(not setup for this). Are you getting any feedbackcomplaints in logs ?

On a similar micro lan the machine having the 2 links

has this set to 1

/proc/sys/net/ipv4/ip_forward

The other has it set to 0.

This 1 might be magical, hope it is but dought it.

Anyway for me all this networking voodoo nat, masquerading, forwarding,

filtering was handled by bastille-firewall (now gone from mdk I hear)

while basic networking was through installation then netconf.

(dont remember much of it I am afraid)

[theYinYeti]

Thanks, b. I'll look into it.

But first, as I wrote on the same subject on MUB1 (at club-nihil), I just remembered that in /etc/ppp/ip-up.local, there's "service bastille-firewall start", so (stupid me again) I'm almost sure I'll correct the problem by reconfiguring the firewall.

 

Yves.

[qeldroma]

Hallo Yeti, wie geht's??

 

:lol:

 

I will be here more often now...

[ranger]

As I see it, when ppp0 becomes default route, it should not be a problem with local network because 10.0.0.X is still routed to eth0. Still, as soon as ppp0 is up, local network freezes (the XDMCP-displayed screen on the laptop becomes still, and no more light-blinking can be seen on the ethernet-switch).

 

Any idea?

 

Yves.

 

I think you need to add an entry for the laptop in the hosts file on the server. This looks like name resolution issues, and that should fix it.

[theYinYeti]

problem solved. It was indeed a firewall problem, as I launch it in ip-up.local, and stop it in ip-down.local. the solution is easy. Bastille-firewall enables you to choose which network interfaces are trusted (no checks), and which are not (firewall in action). I put eth+ in trusted interfaces (no need to firewall anything), and ppp+ in untrusted interfaces (firewall active). Now both PC (connected via modem) and laptop (connected via PC's modem, through XDMCP remote display) can access the web.

 

Yves.