[pptp-server] pptp, gre, adsl firewllas and nat

[John Leach]

On 23 May 2001 12:11:34 +0100, Tim Small wrote:
> I've found CIPE to work quite well in this situation (one end BT ADSL - 
> NATed through a win98 box because I can't get the Linux Speedtouch USB 
> driver working stably :-(  - the other end a permanently connected host).
> 

Ah, I had the BT flowpoint router, which is set up to NAT by default.  I
broke into it and snooped around a bit, turned on protocol 47 forwarding
just in case.  I do see gre traffic at both ends using tcpdump, so I
assume all is well on that front.

> One thing that might be worth doing is knocking the MTU/MRU down - 
> probably something around 1400 will do it, not that the NAT boxes should 
> be choking on GRE fragments, but it is worth a try, and will help 
> performance, if you do get it working.
> 

I shall try this again, I did fiddle with the mtu/mru but only reduced
it if I remember correctly, I'll report results here, thanks.

> CIPE encapsulates over UDP, and doesn't have any problem with any 
> mainstream NAT equipment.

I'd prefer CIPE or proper IPSEC myself, but some lusers needs access
from their win boxes *sigh*