Article 2764 of comp.infosystems.gopher:
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From: lindner@mudhoney.micro.umn.edu (Paul Lindner)
Subject: Re: Proxy agent for gopher
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Organization: University of Minnesota, Minneapolis
References: <ylee.737238632@florida> <C6zu7B.GCy@pandora.sf.ca.us>
Date: Tue, 18 May 1993 21:56:17 GMT
Lines: 140

mitra@path.net (Mitra) writes:

>There are two ways of doing proxy servers with Gopher.  One is at the IP
>level, which sounds like the previous message's method.  I'd be
>interested
>in seeing this.   

>We have a proxy gopher server working atthe application level. It will
>sit on a firewall machine and funnel gopher requests between the two
>sides of the net.  We built it to solve some caching and interface
>conversion problems but it could be fairly easily adapted to meet the
>firewall situation mentioned in several people's messages.

>If anyone needs one of these please get in touch by email, and I'll see
>what could be done.

Here is a firewall gopher translater that runs underneath go4gw, I did
not write it, it was submitted to me..  Have fun :-)

----------snip--------------snip--------------s nip----

From A.Macpherson@bnr.co.uk  Tue May 18 20:09:06 1993
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To: gopher@boombox.micro.umn.edu
Subject: Gopher through a firewall
Date: Tue, 18 May 1993 19:09:06 +0100
From: Andrew Macpherson <A.Macpherson@bnr.co.uk>
Sender: A.Macpherson@bnr.co.uk
Status: OR


Sorry verry silly, I sent you the wrong version, which was missing 2 lines,

I hope it may be usefull to someone


#----------------------------------------------------------------------

@g2go4_acl=(
#     ipaddress  access + = allow, - = deny    
     '^47\.      +',
     '^128.199\.     +',
     '.*         -'
  );

$SafeTypes = "^(0|1|3|4|5|6|7|9)" ;  # Gopher tags we will pass
#----------------------------------------------------------------------

sub g2go4_main {
 local($_ )= @_;

 &Gsorry if /^sorry$/;

  if (&check_access() eq '-') {
      &Greply("0Sorry! No access from Non-Local hosts\t$Ggw sorry\t$Ghost\t$Gport");
      &Greply("."); 
      exit; 
  }

 if (/^$/) {
  &Greply("1Imperial College Archive\t$Ggw 70\007src.doc.ic.ac.uk\007\t$Ghost\t$Gport");
  &Greply(".");
  exit(0);
 }
 ( $port, $host, $query ) = split('\007') ;
 &GopenServer($host, $port);
 &Gsend($query) ;

 # We may be doing a file transfer here, or it may be another menu
 # all we can do is intuit.

 $First = <GSERVER> ;
 $Second = <GSERVER> ;
 if ( $First =~ /^[^\t]*\t[^\t]*\t[^\t]*\t[^\t]*$/ &&
    ($Second eq ".\r\n" ||
     $Second =~ /^[^\t]*\t[^\t]*\t[^\t]*\t[^\t]*$/ )) { # close enough
    $First =~ s/[\r\n]//g ;
  ( $disp, $sel, $host, $port ) = split('\t', $First) ;
    print "${disp}\t$Ggw ${port}\7${host}\7${sel}\t$Ghost\t$Gport\r\n" 
	if $disp =~ m/${SafeTypes}/ ;
    if ($Second eq ".\r\n" ) {
      print $Second ;
      exit 0;
    }
    $Second =~ s/[\r\n]//g ;
  ( $disp, $sel, $host, $port ) = split('\t', $Second) ;
    print "${disp}\t$Ggw ${port}\7${host}\7${sel}\t$Ghost\t$Gport\r\n" 
	if $disp =~ m/${SafeTypes}/ ;
    while(<GSERVER>) {
      s/[\r\n]//g ;
      if ( $_ eq "." ) {
	print ".\r\n" ;
	exit 0;
      }
    ( $disp, $sel, $host, $port ) = split('\t') ;
      print "${disp}\t$Ggw ${port}\7${host}\7${sel}\t$Ghost\t$Gport\r\n" 
	if $disp =~ m/${SafeTypes}/ ;
    }
 } else {
   print $First ;
   print $Second ;
   while(<GSERVER>) {
     print ;
   }
 }
}



sub check_access {

   return 1 if (-t STDIN);
   $sockaddr = 'S n a4 x8';
   $mysockaddr = getpeername(STDIN);
   ($ramily,$rport,$raddr) = unpack($sockaddr,$mysockaddr);
   ($a,$b,$c,$d) = unpack('C4',$raddr);
   $ipaddress = "$a.$b.$c.$d";

   foreach (@g2go4_acl) {
      ($ipacl,$access)=split;
      return $access if  ($ipaddress =~ /$ipacl/);
   }
   return '-'; #default is to restrict access
}

1; # for require


--
 | Paul Lindner | lindner@boombox.micro.umn.edu   | Slipping into madness
 |              | Computer & Information Services | is good for the sake
 | Gophermaster | University of Minnesota         | of comparison.
///// / / /    /////// / / / /  /  /  /   /      //// / / / /  /  /  /   /