Very much appreciate all the tips!

We had an issue with some transparent proxies (the URL is served as http://), where those sometimes add HTTP_X_FORWARDED_FOR but then detail internal IPs. We subsequently may still wish to refer to the remote_addr if all the IPs in the http_x_forwarded_for list are all not valid. The following appears to be working perfectly now:
use Data::Validate::IP qw(is_ip is_public_ip is_loopback_ip);

my $ip;
my @IPs;

if (defined $ENV{HTTP_X_FORWARDED_FOR}) {
  @IPs=split /,/, $ENV{HTTP_X_FORWARDED_FOR};
};
unshift (@IPs, $ENV{REMOTE_ADDR});
foreach $check (@IPs) {
  $check =~ s/^\s*(.*?)\s*$/\1/g;
  if (is_ip($check)) {
    if (defined $ip) {
      if ( (not is_public_ip($check))
        or (is_loopback_ip($check))
        or ($check eq "41.79.21.90") ) {
        $check = $ip;
      }
    }
    $ip = $check;
  }
}

print "Content-type: text/html\nCache-Control: max-age=0,no-cache,no-s
+tore,post-check=0,pre-check=0\n\n<html><head><title>Current IP Check<
+/title></head><body>Current IP Address: $ip</body></html>";

[download]

In reply to Re^3: mod-perl2 re-using $ENV{REMOTE_ADDR} by bbs2web
in thread mod-perl2 re-using $ENV{REMOTE_ADDR} by bbs2web

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.