Re: [pptp-devel] LCP: timeout sending Config-Requests

[Bradley K. <br...@ki...>]

Yeah, the instructions on the web site are a tad faulty - you need to 
have the ppp device up before you can tcpdump to it.
There are a few other gotchas too, which I will document back to James 
once I have sorted everything out my side.

But to answer you Q, this LCP timeout error can be regarded as a 
"generic" error meaning that you are talking to the pptp server but it 
can't go any further than that.

Are you using mppe? I will take a guess that you are.

The web site has an excellent diagnostic set of steps, so go through 
that. I won't repeat what it says because it is very good, very 
comprehensive and does a great job.

However, there are some BIG gotchas not really obvious on the site, 
which I will document here. These are from my own experience. I hope 
that a webmaster for the site is reading this so that they can update it.

For the record, my setup is based on Mandrake 10.0.

If you followed the instructions and you downloaded ppd 2.4.2 and the 
mppe patch, and did the same for the kernel, these three problems will 
hammer you:

   1) there are two possible pppd patches, each making incompatible 
parameter names possible. One, the "standard" one, enables require-mppe, 
where as the newest (and most used online) has "mppe required" as a 
parameter... but pptpconfig doesn't understand this latter parameter set 
so you can waste a lot of time on this.
  2) The module name for mppe in the kernel is different if the latest 
patches to what the web site documents. It documents the old "mppe" and 
the newer "ppp_mppe" but it doesn't yet record "ppp_mppe_mppc". You need 
to alias this in your /etc/modules.conf. Mine looks like this:

    alias ppp-compress-18 ppp_mppe_mppc

  3) The kernel patch and the pppd patch can be incompatible. Please 
check the web site for this. You really need to be certain that you are 
at the same level. But here is another gotacha not yet on the web site: 
The 1.1 patch ONLY works for kernel 2.6.8. If you use anything less than 
that, you need to use 1.0. However, I have had HUGE problems getting 1.0 
to work with some VPNs, so moral of the story is that if you find out 
that you have run into kernel module problems, then you are well advised 
to use the latest patches and 2.6.8.

Having said that, ensure that you install the STANDARD paramters patch. 
If you use the newer parameters form, then you will not be able to use 
pptpconfig properly without changing your /etc/ppp/peers/{VPN} where 
{VPN} is your VPN config.

My guess is that what you really need to do is first turn on debugging 
(debug option) and check if you also need to have the "noauth" option 
added. To use tcpdump, get a terminal with the tcpdump command ready, 
then fire up the VPN with pptpconfig and almost simultaneously hit the 
return key in the tcpdump window... there are better methods that get 
the ppp device up but this is probably your most foolproof and easiest 
option atm.

Hope that this helps!

Brad

Richard Gong wrote:

>Hi, all,
>
>I can't get the pptp client work. It has the following
>error:
>
>    sent [LCP ConfReq id=0x1 <asyncmap 0x0 <magic
>0x8d2b2758> <pcomp> <accomp>]
>
>After trying several times, it terminated by timeout.
>
>The error is got when I run tcpdump -i ppp0
>    ioctl: No such device
>
>How come? Please help.
>
>
>		
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