Telnet command to test DHCP - Networking

This is a discussion on Telnet command to test DHCP - Networking ; Is there a port I can test for a DHCP server? For instance, if I wanted to test web connectivity, I would "telnet [server] 80". Can I "telnet [server] [dhcp port #]"? Or are there multiple ports? Or, does it ...

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Thread: Telnet command to test DHCP

  1. Telnet command to test DHCP

    Is there a port I can test for a DHCP server?

    For instance, if I wanted to test web connectivity, I would "telnet
    [server] 80".

    Can I "telnet [server] [dhcp port #]"? Or are there multiple ports?
    Or, does it use UDP? I don't actually know if telnet works with UDP.

    Little help?


  2. Re: Telnet command to test DHCP


    ha scritto nel messaggio
    news:1130417878.347743.91410@f14g2000cwb.googlegro ups.com...
    > Is there a port I can test for a DHCP server?
    >
    > For instance, if I wanted to test web connectivity, I would "telnet
    > [server] 80".
    >
    > Can I "telnet [server] [dhcp port #]"? Or are there multiple ports?
    > Or, does it use UDP? I don't actually know if telnet works with UDP.
    >
    > Little help?
    >


    Hi,
    the DHCP port is UDP 69. I do not think you can telnet the DHCP server as he
    is waiting
    for BROADCAST messages.

    If you want to play with the DHCP try http://tftpd32.jounin.net
    or use ethereal (google) to see the traffic.

    Regards

    Luc



  3. Re: Telnet command to test DHCP

    tftpd32 seems to be an actual dhcp server, no? I'm looking to test an
    existing dhcp server.


  4. Re: Telnet command to test DHCP


    ha scritto nel messaggio
    news:1130435502.819746.320150@o13g2000cwo.googlegr oups.com...
    > tftpd32 seems to be an actual dhcp server, no? I'm looking to test an
    > existing dhcp server.
    >


    Then Ethereal is the tool !

    Bye

    Luc



  5. Re: Telnet command to test DHCP

    nospam-google.com@zairgit.com wrote:

    > tftpd32 seems to be an actual dhcp server, no? I'm looking to test an
    > existing dhcp server.
    >

    That would be a pretty perverse name for a DHCP server, even in
    Windows-land -- it sounds more like something to do with tftp.

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.

  6. Re: Telnet command to test DHCP


    "CJT" ha scritto nel messaggio
    news:43613D08.3020806@prodigy.net...
    > nospam-google.com@zairgit.com wrote:
    >
    >> tftpd32 seems to be an actual dhcp server, no? I'm looking to test an
    >> existing dhcp server.
    >>

    > That would be a pretty perverse name for a DHCP server, even in
    > Windows-land -- it sounds more like something to do with tftp.
    >
    > --
    > The e-mail address in our reply-to line is reversed in an attempt to
    > minimize spam. Our true address is of the form che...@prodigy.net.


    Yeah,

    actually it is both !

    Bye

    Luc



  7. Re: Telnet command to test DHCP

    O.K. I did an ethereal capture while attempting to "ipconfig /renew
    *". This was what I got:

    http://www.zairgit.net/temp/dhcp.csv
    http://www.zairgit.net/temp/dhcp.htm

    Does that tell you anything about why I get "An error occurred while
    renewing interface Local Area Connection : unable to contact your DHCP
    server. Request has timed out."


    Alan


  8. Re: Telnet command to test DHCP


    "pimpstein" ha scritto nel messaggio
    news:1130512910.510602.238440@g49g2000cwa.googlegr oups.com...
    > O.K. I did an ethereal capture while attempting to "ipconfig /renew
    > *". This was what I got:
    >
    > http://www.zairgit.net/temp/dhcp.csv
    > http://www.zairgit.net/temp/dhcp.htm
    >
    > Does that tell you anything about why I get "An error occurred while
    > renewing interface Local Area Connection : unable to contact your DHCP
    > server. Request has timed out."
    >
    >
    > Alan
    >


    Hi Alan,

    could you please give the following commands ?
    ipconfig/release
    ipconfig/renew
    ipconfig/all > output.txt

    and then post the file output.txt.

    If the DHCP server is not responding (it seems so)
    you should get an IP like 169.254.x.x and NO gateway.

    If you have 0.0.0.0 then the problem is the DHCP client.

    Bye

    Luc



  9. Re: Telnet command to test DHCP

    I had assumed it was the server, since all clients on the network have
    the same problem:

    -------------------------------------------------------------------------------------
    Windows IP Configuration


    Ethernet adapter Local Area Connection:

    Connection-specific DNS Suffix . :
    Autoconfiguration IP Address. . . : 169.254.200.223
    Subnet Mask . . . . . . . . . . . : 255.255.0.0
    Default Gateway . . . . . . . . . :
    ------------------------------------------------------------------------------------

    Right now, there is only one DHCP server on the network (w2k3), which
    seems to be authenticated via AD and pingable by all clients, so I'm
    wondering why the clients wouldn't find it.

    Thanks!

    Alan


  10. Re: Telnet command to test DHCP


    "pimpstein" ha scritto nel messaggio
    news:1130541721.597515.242330@z14g2000cwz.googlegr oups.com...
    >I had assumed it was the server, since all clients on the network have
    > the same problem:
    >
    > -------------------------------------------------------------------------------------
    > Windows IP Configuration
    >
    >
    > Ethernet adapter Local Area Connection:
    >
    > Connection-specific DNS Suffix . :
    > Autoconfiguration IP Address. . . : 169.254.200.223
    > Subnet Mask . . . . . . . . . . . : 255.255.0.0
    > Default Gateway . . . . . . . . . :
    > ------------------------------------------------------------------------------------
    >
    > Right now, there is only one DHCP server on the network (w2k3), which
    > seems to be authenticated via AD and pingable by all clients, so I'm
    > wondering why the clients wouldn't find it.
    >
    > Thanks!
    >
    > Alan
    >


    Hi Alan,

    you are right, the problem is the server !
    In your traces there is nothing related to DHCP OFFER: it seems that the
    requests from the clients do not get to the server.
    Stupid question: is the server on the same LAN ? (no router in between)
    Another stupid question: are you shure the DHCP service has been started ?
    (net start "dhcp server").
    Last one: do you have a firewall somewhere blocking port 67 ?
    Your DHCP server is the one built in windows ?
    Give tftp32 a chance, it is easy to control and configure: just to try to
    isolate the problem.
    Let me know how you proceed .

    Regards

    Luc



  11. Re: Telnet command to test DHCP

    Answers to your questions before I try tftp32:

    Server is on the same LAN separated by a switch. This is certain,
    since I can ping it, terminal into it, etc. from any client on the LAN.

    DHCP is absolutely started. I just verified through services MMC.
    (DHCP Server)

    No 3rd party firewall anywhere on network; There is another box on the
    network - the gateway - with a WAN interface on external interface (two
    nics) protected by ISA; windows firewall service is stopped on the DHCP
    server and on the client it is not enabled for the NIC.

    DHCP server is the windows service that comes with Windows 2003.

    Unless any of those answers helped diagnose, I'm off to try tftp.


    Thanks!

    Alan


  12. Re: Telnet command to test DHCP

    pimpstein wrote:

    > Answers to your questions before I try tftp32:
    >
    > Server is on the same LAN separated by a switch. This is certain,
    > since I can ping it, terminal into it, etc. from any client on the LAN.
    >
    > DHCP is absolutely started. I just verified through services MMC.
    > (DHCP Server)
    >
    > No 3rd party firewall anywhere on network; There is another box on the
    > network - the gateway - with a WAN interface on external interface (two
    > nics) protected by ISA; windows firewall service is stopped on the DHCP
    > server and on the client it is not enabled for the NIC.
    >
    > DHCP server is the windows service that comes with Windows 2003.
    >
    > Unless any of those answers helped diagnose, I'm off to try tftp.


    You say you're running 2K3? Have you authorized the DHCP server? Until you
    do it won't service requests? If you're not sure, go into the windows help
    and search DHCP and there's a procedure described.

    > Thanks!
    >
    > Alan


    --
    --John
    to email, dial "usenet" and validate
    (was jclarke at eye bee em dot net)

  13. Re: Telnet command to test DHCP

    I set up the DHCP server on the domain controller, as an experiment.
    That seemed to work. So I re-set-up the other one with settings to
    mirror it. That worked!

    I think I must not have gone through the "extra" settings phase when I
    set it up the first time. Thanks for all your help, my friends.


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