how to use compress modul in ppp process

how to use compress modul in ppp process

[C.J]

Hi list,                            
I got some troubles on ppp_mppe. After successful negotiation with parameter mppc-128bit encrypt, I cannot get decompressed package.

Between server and client, I got the comp_data package with wireshark also in my client I can get this package( which is not decompressed at all ).

I found ppp_mppe module decomp_init has been called successful. But why it couldn't work for me? 

I only know that we need call ioctl(PPPIOCSCOMPRESS) to set compressor and call ccp_test which is set COMP flags. Both of them I've use in my client.

Any ideas? 






Thx & Regards

--
cj
 

Re: how to use compress modul in ppp process

[Charlie Brady]

On Fri, 25 Apr 2008, C.J wrote:

> I got some troubles on ppp_mppe. After successful negotiation with 
> parameter mppc-128bit encrypt ...

MPPC is patent burdened, and not very widely available. Are you quite sure 
that you have it available in your kernel (or kernel modules)?

Re: Re: how to use compress modul in ppp process

[Charlie Brady]

On Fri, 25 Apr 2008, C.J wrote:

> Hi Charlie Brady

Please do not reply to just me. Please keep any replies on the list (and 
preferably, only on the list).

>> MPPC is patent burdened, and not very widely available. Are you quite sure
>> that you have it available in your kernel (or kernel modules)?
> I knew that pppd can use ppp_mppe.  On the mppe log there are some messages as below :
> 	comp count xxx: xxx
> 	decomp count xxx: xxx
> So we can tell it works for pppd well.

I don't know that anything you have said indicates that MPPC is available. 
It rarely is.

Re: Re: Re: how to use compress modul in ppp process

[C.J]

Hi ,

>I don't know that anything you have said indicates that MPPC is available. 
>It rarely is.
Sorry for mine behavior. I thought it maybe the pppol2tp driver's bug(have not handle this case). Now I'll ask l2tp user about that.

--
c.j

Re: Re: Re: how to use compress modul in ppp process

[Charlie Brady]

On Fri, 25 Apr 2008, C.J wrote:

> Hi ,
>
>> I don't know that anything you have said indicates that MPPC is available.
>> It rarely is.
>
> Sorry for mine behavior. I thought it maybe the pppol2tp driver's 
> bug(have not handle this case).

Why did you think that?

> Now I'll ask l2tp user about that.

I very much doubt that will be relevant.

l2tp is just an encapsulation layer which has nothing to do with MPPC.

Do you have a good reason for apparently ignoring my statement that MPPC 
is usually not supported by the ppp modules in the kernel? Are you quite 
sure that your kernel (or kernel modules) has been specifically patched to 
support MPPC? If not, you cannot use MPPC, not matter how you configure 
your client.

Re: Re: Re: how to use compress modul in ppp process

[C.J]

Hi,

>Why did you think that?
Since I got a strange package with protocol field 0xFD(not 0x00FD). 
I've read ppp_generic.txt and got that the upper layer should pass packages to ppp_generic driver with two octets protocol field. 
So this should be finished on l2tp layer(channel preferably) or other kinds of channel.
 
>l2tp is just an encapsulation layer which has nothing to do with MPPC.
You are right.

>Do you have a good reason for apparently ignoring my statement that MPPC 
>is usually not supported by the ppp modules in the kernel? Are you quite 
>sure that your kernel (or kernel modules) has been specifically patched to 
>support MPPC? If not, you cannot use MPPC, not matter how you configure 
>your client.
Really? But in my machine(which kernel is 2.6, Debian system) has ppp_mppe module but no any patch. Also has other compress module such as bsd_comp, deflate.
Does this mean that kernel support it and I can use it? 

Thanks so much for your kindly reply.
Regards.

--
c.j

Re: Re: Re: how to use compress modul in ppp process

[James Cameron]

On Sat, Apr 26, 2008 at 08:10:50PM +0800, C.J wrote:
> Charlie wrote:
> >Do you have a good reason for apparently ignoring my statement that MPPC 
> >is usually not supported by the ppp modules in the kernel? Are you quite 
> >sure that your kernel (or kernel modules) has been specifically patched to 
> >support MPPC? If not, you cannot use MPPC, not matter how you configure 
> >your client.
> Really? But in my machine(which kernel is 2.6, Debian system) has
> ppp_mppe module but no any patch.

Debian kernels do not have MPPC support, because of (a) kernel.org
kernel does not have MPPC support, and (b) the patent issue.

The ppp_mppe module provides MPPE support, not MPPC support.

> Also has other compress module such as bsd_comp, deflate.

This is not relevant.

> Does this mean that kernel support it and I can use it? 

No.

-- 
James Cameron                         http://quozl.netrek.org/
HP Open Source, Volunteer             http://opensource.hp.com/
PPTP Client Project, Release Engineer http://pptpclient.sourceforge.net/