ppp transactions with XP using Null Modem - PPP

This is a discussion on ppp transactions with XP using Null Modem - PPP ; Hi, I am working on an embedded system that is connected to the PC through a Null Modem driver (mdmcbx.inf). I have managed to exchange a few ppp packets but I am now stuck in negotiating the pap exchange..in brief: ...

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  1. ppp transactions with XP using Null Modem

    Hi,

    I am working on an embedded system that is connected to the PC through
    a Null Modem driver (mdmcbx.inf). I have managed to exchange a few ppp
    packets but I am now stuck in negotiating the pap exchange..in brief:
    embedded system xp
    ----------------- --------------
    lcp config request (pap,,)
    lcp config ack
    lcp config request
    lcp config ack
    pap request (name,password)
    pap ack
    ipcp config req (ip address)
    no response

    I have discovered that with my pap ack I need to return back the name
    and password with the ack or else xp keeps on requesting till it
    gives up.
    The 2 systems stops communicating after I send the ipcp config req (ip
    addr).
    I am thinking that even if I keep on sending this request it would not
    help. I will be trying this next. I am also thinking that I may have
    to send a pap request (or chap request) before xp will proceed
    further.

    Does anyone have a clue on what exchanges are required and if anyone
    has a trace of a successful connection I will be very grateful?

    Also, although I've got the null modem to work using mdmcbx.inf, can
    anyone explain some of the lines of code in there? All I do on startup
    is I ignore all the exchanges, like HELLO etc and just pump out my lcp
    request which gets acknowledged.

    Any help will be much appreciated.

    Thanks.

  2. Re: ppp transactions with XP using Null Modem

    On 27 Aug 2004 22:28:18 -0700, Lee Chua wrote:

    > Does anyone have a clue on what exchanges are required and if anyone has a
    > trace of a successful connection I will be very grateful?


    There are probably a lot of folks here who can answer your question better
    than I can, but maybe this will help (originating end of a connection to an
    NT server):

    sent [LCP ConfReq id=0x1 ]
    rcvd [LCP ConfReq id=0x1 < 00 04 00 00>
    ]
    sent [LCP ConfRej id=0x1 < 00 04 00 00> ]
    rcvd [LCP ConfAck id=0x1 ]
    rcvd [LCP ConfReq id=0x2
    ]
    sent [LCP ConfAck id=0x2
    ]
    sent [PAP AuthReq id=0x1 user="some guy" password="some password"]
    rcvd [PAP AuthAck id=0x1 ""]
    sent [CCP ConfReq id=0x1 ]
    sent [IPCP ConfReq id=0x1 ]
    rcvd [IPCP ConfReq id=0x1 ]
    sent [IPCP ConfAck id=0x1 ]
    rcvd [LCP ProtRej id=0x3 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]

    rcvd [IPCP ConfNak id=0x1 ]
    (Nak for "Local Addr" IPCP req)

    sent [IPCP ConfReq id=0x2 rcvd [IPCP ConfAck id=0x2
    --
    If you can see the FNORD, remove it to reply by email.

  3. Re: ppp transactions with XP using Null Modem

    Thanks RL,

    I am sure there are lots of good and clever folks out there that could
    have responded too, and I thank you, being one of them, for your quick
    response.

    I will examine the exchanges you have given and try it out.

    Lee

  4. Re: ppp transactions with XP using Null Modem

    In article <3142f5e0.0408272128.4baf0df7@posting.google.com>,
    Lee Chua wrote:
    >Hi,
    >
    >I am working on an embedded system that is connected to the PC through
    >a Null Modem driver (mdmcbx.inf). I have managed to exchange a few ppp
    >packets but I am now stuck in negotiating the pap exchange..in brief:
    >embedded system xp
    >----------------- --------------
    >lcp config request (pap,,)
    > lcp config ack
    > lcp config request
    >lcp config ack
    > pap request (name,password)
    >pap ack
    >ipcp config req (ip address)
    > no response
    >
    >I have discovered that with my pap ack I need to return back the name
    >and password with the ack or else xp keeps on requesting till it
    >gives up.
    >The 2 systems stops communicating after I send the ipcp config req (ip
    >addr).


    Can you provide the actual packets (bytes or full decodes would be most
    helpful)?

    >Also, although I've got the null modem to work using mdmcbx.inf, can
    >anyone explain some of the lines of code in there? All I do on startup
    >is I ignore all the exchanges, like HELLO etc and just pump out my lcp
    >request which gets acknowledged.


    Again, a full dump of data going back and forth might be helpful. Last
    I recall, Windows null-modem "driver" utilized a handshake where the
    server sends "SERVER", and the client sends "CLIENT" (after echoing
    "SERVER"). Are you not seeing that??

    ========= For LAN/WAN Protocol Analysis, check out PacketView Pro! =========
    Patrick Klos Email: patrick@klos.com
    Klos Technologies, Inc. Web: http://www.klos.com/
    ==================== What goes around, comes around... =====================

  5. Re: ppp transactions with XP using Null Modem

    patrick@klos.com wrote:
    > In article <3142f5e0.0408272128.4baf0df7@posting.google.com>,
    > Lee Chua wrote:


    >>Also, although I've got the null modem to work using mdmcbx.inf, can
    >>anyone explain some of the lines of code in there? All I do on startup
    >>is I ignore all the exchanges, like HELLO etc and just pump out my lcp
    >>request which gets acknowledged.


    > Again, a full dump of data going back and forth might be helpful. Last
    > I recall, Windows null-modem "driver" utilized a handshake where the
    > server sends "SERVER", and the client sends "CLIENT" (after echoing
    > "SERVER"). Are you not seeing that??


    In that exchange doesn't the "client" send CLIENT and the "server"
    responds with CLIENTSERVER?

    --
    Clifford Kite Email: "echo xvgr_yvahk-ccc@ri1.arg|rot13"
    PPP-Q&A links, downloads: http://ckite.no-ip.net/
    /* Better is the enemy of good enough. */

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