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Date: Thu, 31 Oct 2002 18:06:06 +0100
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Message-ID: <20021031170606.GB20459@mail.archlab.tuwien.ac.at>
References: 
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From: Cahya Wirawan <cwirawan@email.archlab.tuwien.ac.at>
Subject: Re: [users@httpd] Testing if a Webserver is down

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Ok, I forget to check the unknown host, in your case it was succesfull 
connected and get http answer because if the host unknown, it connected 
to localhost and you have a webserver running on localhost :)
also I just inserted one line to check the host.

cahya.

On Thu, Oct 31, 2002 at 10:43:29AM -0500, Kyle wrote:
> Cahya,
> 
> The program you attached always gives a "successful" reply even for 
> non-existent servers.  :(
> 
> I only wanted to run it once, so I changed the "while(1){" to "if(1){" 
> to make it run one time.  I wanted to see the failure output, so he 
> server I chose to test was a fake one: www.asdfljja.com
> 
> Here is what happens on one of my servers:
> [dustdevil:/test root]# ./checkwebserver.pl
> Thu Oct 31 10:16:48 2002: Testing www.asdfljja.com on port 80 ...
> Thu Oct 31 10:16:48 2002: GET / answered.
> Thu Oct 31 10:16:48 2002: Connected successfully.
> 
> But there is no such server.
> 
> BTW, I think this approach is great.  It is a compromise between the 
> complexity of the wget/ultramonkey suggestions and the simplistic ping 
> options, which I think is a good fit for the majority of the Apache 
> sysadmins.  If you correct the problem, I hope you will repost your 
> program to the group.
> 
> -Kyle
> 

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#!/usr/bin/perl=0A=0A$Host =3D "webserver.hostname.org";=0A$Port =3D 80;=0A=
$Interval =3D 5; #in second=0A=0A$AF_INET =3D 2;=0A$SOCK_STREAM =3D 1;=0A$s=
ockaddr =3D 'S n a4 x8';=0Achop($localHostname =3D `hostname`);=0A=0Awhile(=
1) {=0A  testservice($Host,$Port);=0A  sleep $Interval;=0A}=0A=0Asub testse=
rvice {=0A  local($testhost,$testport) =3D @_;=0A  $now =3D localtime;=0A=
=0A  print STDERR "$now: Testing $testhost on port $testport ...\n";=0A =0A=
  ($name,$aliases,$proto) =3D getprotobyname('tcp');=0A  ($name, $aliases, =
$type, $len, $thisaddr) =3D gethostbyname($localHostname);=0A  $this =3D pa=
ck($sockaddr, $AF_INET, 0, $thisaddr);=0A=0A  ($name,$aliases,$testport) =
=3D getservbyname($testport,'tcp')=0A    unless $testport =3D~ /^\d+$/;;=0A=
  ($name, $aliases, $type, $len, $thataddr) =3D gethostbyname($testhost);=
=0A  die "$now: $testhost is unknown host!\n" unless $thataddr;=0A  $that =
=3D pack($sockaddr, $AF_INET, $testport, $thataddr);=0A=0A  # Create a hand=
le to the socket=0A  if (!socket(S, $AF_INET, $SOCK_STREAM, $proto)) {=0A  =
  $reason =3D $!;=0A    print STDERR "$now: socket failed: $reason\n";=0A  =
  return;=0A  }=0A  # Assign the socket an address=0A  if (!bind(S, $this))=
 {=0A    $reason =3D $!;=0A    print STDERR "$now: bind failed: $reason\n";=
=0A    return;=0A  }=0A=0A  # Connect to the server=0A  if (!connect(S,$tha=
t)) {=0A    $reason =3D $!;=0A    print STDERR "$now: connect failed: $reas=
on\n";=0A    shutdown(S,2);=0A    close(S);=0A    return;=0A  }=0A=0A  # El=
iminate buffering on this socket=0A  select(S);	  $| =3D 1;=0A=0A  # If it'=
s a Web service, use the GET method=0A=0A  if ($testport =3D=3D 80) {=0A   =
 print S "GET / HTTP/1.0\n\n";=0A    eval {=0A      local $SIG{ALRM} =3D su=
b { die "alarm\n" };=0A      alarm 30;=0A      $nread =3D sysread S,$buffer=
,10;=0A      alarm 0;=0A    };=0A    if ($@) {=0A      $reason =3D "answer =
time out";=0A      print STDERR "$now: GET / failed: $reason\n";=0A      sh=
utdown(S,2);=0A      close(S);=0A      return;=0A    }=0A    print STDERR "=
$now: GET / answered.\n";=0A  }=0A=0A  print STDERR "$now: Connected succes=
sfully.\n";=0A=0A  shutdown(S,2);=0A  close(S);=0A}=0A=0A

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