Find out if a host is alive

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  • Anand Pillai
    #1

    Find out if a host is alive

    I would like to add a feature to one of my network programs.
    The requirement is to find out if a server is alive by sending
    it requests. I know of the standard ICMP ping, and searched
    for python modules able to 'PING'. The only hit I got was Jeremy
    Hiltons ping package, written for Python 1.4, and it does not
    work with the latest Python versions (2.0 upwards).

    Are there other ways of finding out (in a few lines of code)
    whether a server is alive, apart from the ICMP protocol?

    Thanks for your help.

    -Anand
    Tags: None
    • Alex Martelli
      #2
      Re: Find out if a host is alive

      Anand Pillai wrote:
      [color=blue]
      > I would like to add a feature to one of my network programs.
      > The requirement is to find out if a server is alive by sending
      > it requests. I know of the standard ICMP ping, and searched
      > for python modules able to 'PING'. The only hit I got was Jeremy
      > Hiltons ping package, written for Python 1.4, and it does not
      > work with the latest Python versions (2.0 upwards).[/color]

      http://pynms.sourceforge.net/ does appear to support ICMP, among
      many other things, and to support Python 2.2 (I'd be quite amazed
      if it worked with 2.2 and not with 2.3).
      [color=blue]
      > Are there other ways of finding out (in a few lines of code)
      > whether a server is alive, apart from the ICMP protocol?[/color]

      If you know what services the server is supposed to be running,
      sure. If you have no idea whatsoever, no way. It's quite
      imaginable, for example, that a server does not serve ICMP
      (doesn't WANT to be pinged nor tracerouted etc) but only,
      strictly HTTP on port 80/TCP _period_. If you know that, then
      'pinging' the server is useless as a way to determine whether
      the server 'is alive'; rather, you would try to bind a socket
      to its TCP port 80, and, depending on your definition of "being
      alive", might claim that just managing to bind that socket is
      enough (or, you might try some short HTTP transaction on the
      socket).

      I've noticed an analogy between people wanting their programs
      to check if "a server is alive" and ones wanting their programs
      to check if "a file exists": the question they pose is rarely
      the one they really need to get answered; for example, the
      mere existence of a file is often of no real interest if the
      program does not have permission to _read_ the file -- and
      the mere "aliveness" of a host is often of no real interest
      if the program does not have permission to _talk_ to the host
      along at least one protocol that's of actual _use_...


      Alex

        Comment

        • Anand Pillai
          #3
          Re: Find out if a host is alive

          Thank You Alex. What I want is actually answered by you.
          I would like to find if the server is answering HTTP requests
          at port 80.

          I checked out pyheartbeat, but I think it is useful only for
          computers in the local area network and not the internet.

          -Anand

          Alex Martelli <aleax@aleax.it > wrote in message news:<ccCfb.224 602$R32.7219630 @news2.tin.it>. ..[color=blue]
          > Anand Pillai wrote:
          >[color=green]
          > > I would like to add a feature to one of my network programs.
          > > The requirement is to find out if a server is alive by sending
          > > it requests. I know of the standard ICMP ping, and searched
          > > for python modules able to 'PING'. The only hit I got was Jeremy
          > > Hiltons ping package, written for Python 1.4, and it does not
          > > work with the latest Python versions (2.0 upwards).[/color]
          >
          > http://pynms.sourceforge.net/ does appear to support ICMP, among
          > many other things, and to support Python 2.2 (I'd be quite amazed
          > if it worked with 2.2 and not with 2.3).
          >[color=green]
          > > Are there other ways of finding out (in a few lines of code)
          > > whether a server is alive, apart from the ICMP protocol?[/color]
          >
          > If you know what services the server is supposed to be running,
          > sure. If you have no idea whatsoever, no way. It's quite
          > imaginable, for example, that a server does not serve ICMP
          > (doesn't WANT to be pinged nor tracerouted etc) but only,
          > strictly HTTP on port 80/TCP _period_. If you know that, then
          > 'pinging' the server is useless as a way to determine whether
          > the server 'is alive'; rather, you would try to bind a socket
          > to its TCP port 80, and, depending on your definition of "being
          > alive", might claim that just managing to bind that socket is
          > enough (or, you might try some short HTTP transaction on the
          > socket).
          >
          > I've noticed an analogy between people wanting their programs
          > to check if "a server is alive" and ones wanting their programs
          > to check if "a file exists": the question they pose is rarely
          > the one they really need to get answered; for example, the
          > mere existence of a file is often of no real interest if the
          > program does not have permission to _read_ the file -- and
          > the mere "aliveness" of a host is often of no real interest
          > if the program does not have permission to _talk_ to the host
          > along at least one protocol that's of actual _use_...
          >
          >
          > Alex[/color]

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