Re: pppd[32497]: Unsupported protocol 'CallBack Control Protocol (CBCP)' (0xc029) received

From: Randy.Dunlap (
Date: Tue Aug 06 2002 - 15:01:14 EST

On Tue, 6 Aug 2002, Richard B. Johnson wrote:

| On Tue, 6 Aug 2002, Diego Calleja wrote:
| > In different kernels I've seen this message:
| >
| > Aug 6 19:10:01 localhost pppd[32497]: Unsupported protocol 'CallBack
| > Control Protocol (CBCP)' (0xc029) received
| >
| > Is pppd who has to handle this protocol, or it's a "ToDo" in ppp in the
| > kernel? In the last case, will it be implemented?
| >
| > and, what's the hell is the "Callback Protocol?"
| You are connected to a M$ 'server' and it's trying to interrogate
| your machine with 'Magic Lantern'. I don't think you want it
| implemented. From what I hear, it's what the US Government decided
| that M$ must put into everything so that any 'Duly authorized....'
| can peer into your computer.
| Check it out. Scary...

I've never heard this explanation, but who knows??

I've heard of callback relating to RAS as a method of preventing
just anyone calling into a particlar RAS server.
Using callbacks, the server hangs up and immediately calls the
originator back to a valid, known telephone number.
Also allows the server to be billed for it instead of the caller.

At MS web site:
Callback Negotiation with the Callback Control Protocol
The Callback Control Protocol (CBCP) is documented in .
CBCP negotiates the use of callback where the remote access server,
after authenticating the remote access client, terminates the physical
connection, waits a specified amount of time, and then calls the remote
access client back at either a static or dynamically configured phone
number. Common CBCP options include the phone number being used by the
remote access server to call the remote access client back.


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