Help with cu and xinetd - Linux

This is a discussion on Help with cu and xinetd - Linux ; I am pretty new to xinetd and uucp. I am trying to setup a reverse telnet terminal server with Fedora 9. I am using cu from the taylor uucp package and I am using xinetd to start cu. Everything works ...

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Thread: Help with cu and xinetd

  1. Help with cu and xinetd

    I am pretty new to xinetd and uucp. I am trying to setup a reverse
    telnet terminal server with Fedora 9. I am using cu from the taylor
    uucp package and I am using xinetd to start cu.

    Everything works fine if I telnet to port 23 and start "cu -s 9600 -l
    /dev/ttyS1" from the command line, but if I start cu through xinetd I
    get double or triple echos. Also, I get a ^@ everytime I press enter.

    Does anyone have any idea what is causing the extra echos or the ^@
    after I press enter? or how to avoid the extra echos? I've turned off
    localecho when I telnet into cu, but I still get the double and triple
    echo.

    Here is my xinetd config for cu below

    # default: off
    # description: The reverse telnet console server serves console
    sessions via
    # telnet sessions; it uses unencrypted communications and
    is NOT
    # authenticated.
    service console1
    {
    type = UNLISTED
    flags = REUSE
    socket_type = stream
    port = 3002
    wait = no
    user = root
    server = /usr/bin/cu
    server_args = -s 9600 -l /dev/ttyS1
    disable = no
    }

    Here is an example of what the telnet session looks like

    R7#shos ho ip iinp tin btrie brie
    R7#enaenablbele

    R7#
    R7#^@

    Thanks for any help.

    Brian Burns

  2. Re: Help with cu and xinetd


    On Sun, 2008-11-09 at 17:10 +0000, Brian Burns wrote:
    > I am pretty new to xinetd and uucp. I am trying to setup a reverse
    > telnet terminal server with Fedora 9. I am using cu from the taylor
    > uucp package and I am using xinetd to start cu.


    Firstly, why are you using cu and uucp? I used to use it about 15-20
    years ago, but with the advent of faster networks I now do everything
    with ssh/rcp or rsync.

    Even if you have to use a dial-up connection, you can establish the
    connection with diald/pppd or the like and then use ssh.





  3. Re: Help with cu and xinetd

    Thanks for the reply. I am trying to muddle through this and don't
    know the best approach.

    I am using a RocketPort 8J serial card and a Digi Accelleport XEM to
    connect to a rack of Cisco routers and switches. I have a web page
    with a Java Telnet plugin and I'm just looking for a simple way to
    connect a Java Telnet Client directly to ttyS1 - ttyS16

    My goal is to have a user click on a link to open a Java Telnet
    session to TCP port 3001 - 30016. All my routers use TACACS+
    authentication, so I don't care about authenticating the user on
    Telnet/SSH session.

    I am using cu because I don't know of any other way to pipe a telnet
    session directly to the serial port. I wont be doing any dialing or
    connecting to modems.

    I haven't found any information on how to connect an SSH session
    directly to a serial port, and I don't want to give the user access to
    the operating system.

    I just found termnetd, but I am having trouble getting any output at
    all that.

    I am open to any suggestions if there is a better way to do this.

    Thanks for any help.

    Brian Burns

    On Mon, 10 Nov 2008 12:23:17 +0000, Raphael Mankin
    wrote:

    >
    >On Sun, 2008-11-09 at 17:10 +0000, Brian Burns wrote:
    >> I am pretty new to xinetd and uucp. I am trying to setup a reverse
    >> telnet terminal server with Fedora 9. I am using cu from the taylor
    >> uucp package and I am using xinetd to start cu.

    >
    >Firstly, why are you using cu and uucp? I used to use it about 15-20
    >years ago, but with the advent of faster networks I now do everything
    >with ssh/rcp or rsync.
    >
    >Even if you have to use a dial-up connection, you can establish the
    >connection with diald/pppd or the like and then use ssh.
    >
    >
    >


  4. Re: Help with cu and xinetd


    On Mon, 2008-11-10 at 22:52 +0000, Brian Burns wrote:
    > Thanks for the reply. I am trying to muddle through this and don't
    > know the best approach.
    >
    > I am using a RocketPort 8J serial card and a Digi Accelleport XEM to
    > connect to a rack of Cisco routers and switches. I have a web page
    > with a Java Telnet plugin and I'm just looking for a simple way to
    > connect a Java Telnet Client directly to ttyS1 - ttyS16
    >
    > My goal is to have a user click on a link to open a Java Telnet
    > session to TCP port 3001 - 30016. All my routers use TACACS+
    > authentication, so I don't care about authenticating the user on
    > Telnet/SSH session.
    >
    > I am using cu because I don't know of any other way to pipe a telnet
    > session directly to the serial port. I wont be doing any dialing or
    > connecting to modems.
    >
    > I haven't found any information on how to connect an SSH session
    > directly to a serial port, and I don't want to give the user access to
    > the operating system.
    >
    > I just found termnetd, but I am having trouble getting any output at
    > all that.
    >
    > I am open to any suggestions if there is a better way to do this.
    >


    Then it sounds as if 'cu' is really the way to go. However, trying to
    open a telnet session from a web page sounds rather obtuse.

    It is possible to get your web server to act as a proxy between the user
    and your CISCOs, but it is not what it is designed to do. Web servers
    are really biased towards short, self-contained transactions.

    I suggest, either let your users connect directly to the CISCOs or, if
    this is not possible, write a custom server in Perl, Python, or
    whatever, to do the proxying. That way you have full control over what
    is going on.

    Another way is to let users ssh to the server having the serial
    interfaces and then run cu directly in their terminal session.


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