[HPADM] SUMMARY: Monitor Socket Connection Attempts?

From: Jim Turner (JTurner_at_hertz.com)
Date: 05/06/03

  • Next message: Matthew McCleary: "[HPADM] Re: Looking for HP-UX 10.20 media"
    To: hpux-admin@dutchworks.nl
    Date: Tue, 6 May 2003 15:02:24 -0500
    
    

    Thanks to all who replied (listed in chronological order):
              IlicR@stentor.ca
              Mike.Keighley@lexicon.co.uk
              "Ed" <ed1901@hotmail.com>
              IlicR@stentor.ca
              Ben Le <ble@pcc.edu>
              "Bill Hassell" <blhconsulting@mindspring.com>
              "Brett Geer" <brett.geer@dhl.com>
              "Ekstrom Christopher A" <EkstromChristopherA@JohnDeere.com>
              Dave Ritchie <deritchie@yahoo.com>
    Replies as well as my original post appear below. In a nutshell, it was a
    mucked-up firewall ACL that jammed traffic coming to us. We used inetd's
    logging (inetd -l) to prove what we suspected all along -- we were not
    receiving a connection request from the vendor.

    ++++++++++ IlicR@stentor.ca:

    Use lsof this is free product and will provide your requirements.
    Usage lsof -i:your_port_number it will show all socet connection ( port +
    IP
    address).
    With netstat this is not possible.

    Hope it helps.

    ++++++++++ Mike.Keighley@lexicon.co.uk:

    Start the inet daemon with the "-l" option.
    e.g. kill inetd, then: inetd -l

    or, edit /etc/rc.config.d/netdaemons to include:
    export INETD_ARGS="-l"
    and restart

    ++++++++++ "Ed" <ed1901@hotmail.com>:

    In a similar previous experience it turned out that my box was running a
    software firewall (ipchains) by default, blocking all or most traffic,
    which I didn't know about. Check if yours is doing that too.

    ++++++++++ IlicR@stentor.ca:

    Hmmmm , Not quite sure what you want to prove? Lsof will list all
    established
    connection.
    It shouldn't be any problem to specify IP address ( lsof | grep
    your_required_IP_addres).
    I bet you what real problem is on firewall ACL is not updated properly. No
    connection is made at all. How to prove "attempt" !?
    At least you would be able to provide more info. It take just 1-2 minutes
    to
    download and
    install.

    ++++++++++ Ben Le <ble@pcc.edu>:

    Try the following command:
    /usr/bin/last -R

    ++++++++++ "Bill Hassell" <blhconsulting@mindspring.com>:

    You can use nettl and inetd -l to trace the connections. My guess is that
    nothing is reaching
    your server because your firewall is preventing the connection. It's easy
    to verify this by
    simply using telnet from the remote system specifying the port(s) that
    will be used
    in MQ Series (make sure you know all of them by number). Connection
    refused
    messages (without any connection records in HP-UX) is a sure sign that the

    network is denying access, not HP-UX.

    ++++++++++ "Brett Geer" <brett.geer@dhl.com>:

    best bet I'd think would be tcpdump. It's truely a handy tool

    ++++++++++ "Ekstrom Christopher A" <EkstromChristopherA@JohnDeere.com>:

    If someone hasn't mentioned it already I would try out tcp dump, you can
    get
    it from the HPUX Porting and Archive center (UTAH) This will provide a
    dynamic connection status which you can drig through to search for the
    connection you don't believe is reaching the box.

    http://hpux.cs.utah.edu/hppd/cgi-bin/search

    ++++++++++ Dave Ritchie <deritchie@yahoo.com>

       try doing a 'telnet machine.hertz.com <socket#>' and see if it shows up
    in
    the application logs - if you can do that and you see that connection in
    your log, it pretty much implies that the outside connection is not
    getting
    through, and that there is something 'inbetween' that is not forwarding.

        Another way to do this is to place a sniffer on that port and see what
    traffic is going across the wire - Linux boxes are useful for doing this.

    Good luck with it!

    Is this is a TCP or UDP packet, BTW? Most routers don't forward UDP by
    default....

    ++++++++++

    I should add that we can connect to the queue in question from a local
    server with no problem at all. Sorry for the extra bandwidth for the
    addendum.

    Greetings!

    Here's the situation: I'm working with an outside vendor that connects to
    us via MQ Series through a firewall to a server in our environment. The
    vendor says he's making a connection attempt. The LAN guys say they see
    the connection attempt at the firewall and that it must be a problem on
    "our end" not accepting the connection. However, I never see a socket
    connection from the vendor with netstat. Further, it is our contention
    that the connection request is never making it to our box.

    Is there a good way to reliably monitor/log all TCP connection attempts
    (successful and unsuccessful) that my HP-UX box gets?

    Thanks!
    Jim

    [Cross-posted to itrc hp-ux forum]

    ===========================
    Jim Turner
    Sr. UNIX Systems Programmer
    The Hertz Corporation

    "In the beginning of a change, the patriot is a scarce man and brave,
    hated and scorned. When his cause succeeds however, the timid join him,
    for then it costs nothing to be a patriot." --Mark Twain

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