commit b5c1232b78a0bbe0b0bd4ba9b5ec17c8f974876b
Author: Florian Obser <florian@narrans.de>
Date:   Mon Apr 24 17:34:37 2017 +0200

    Initial commit

diff --git a/sshdyndns b/sshdyndns
new file mode 100755
index 0000000..7c0ed28
--- /dev/null
+++ b/sshdyndns
@@ -0,0 +1,148 @@
+#! /usr/bin/perl
+# Copyright (c) 2017 Florian Obser <florian@narrans.de>
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+use strict;
+use warnings;
+use 5.010;
+use autodie;
+
+use Getopt::Long;
+use MIME::Base64;
+use Net::DNS;
+use Net::DNS::RR::TSIG;
+use Pod::Usage;
+
+my $port = 53;
+my $ttl = 3600;
+my $help = 0;
+my ($tsigname, $tsigkey, $server, $verbose, $tsig);
+my ($old_rr, $new_rr, $update, $resolver, $reply, $ip);
+
+GetOptions("help|?" => \$help,
+	   "verbose" => \$verbose,
+	   "port=i" => \$port,
+	   "server=s" => \$server,
+	   "ttl=i" => \$ttl,
+	   "tsigname=s" => \$tsigname,
+	   "tsigkey=s" => \$tsigkey)
+    or die("Error in command line arguments\n");
+
+pod2usage(1) if ($help or scalar(@ARGV) != 2);
+
+my ($zone, $label) = @ARGV;
+
+if (!defined $server) {
+    say STDERR "DNS Server missing.";
+    pod2usage(1);
+}
+
+if($ENV{SSH_CLIENT}=~/^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}) (\d{1,5}) 22$/) {
+    $ip = $1;
+} else {
+    say STDERR "cannot pare remote IP";
+    pod2usage(1);
+}
+
+$old_rr = rr_del("$label A");
+$new_rr = rr_add("$label $ttl A $ip");
+
+say "del: ", $old_rr->string  if (defined $old_rr && $verbose);
+say "add: ", $new_rr->string  if (defined $new_rr && $verbose);
+
+$update = new Net::DNS::Update($zone);
+
+if (defined $old_rr && defined $new_rr) {
+    $update->push(update => rr_del($old_rr->string), rr_add($new_rr->string));
+} else {
+    say STDERR "old and new record not defined, don't know what to do";
+    exit(1);
+}
+
+if (defined $tsigname && defined $tsigkey) {
+    $tsig =  Net::DNS::RR::TSIG->create($tsigname, $tsigkey);
+    say $tsig->string if ($verbose);
+    $update->push( additional => $tsig);
+}
+
+say $update->string if ($verbose);
+
+$resolver = new Net::DNS::Resolver;
+$resolver->nameservers($server);
+$resolver->port($port);
+
+$reply = $resolver->send($update);
+
+if ($reply) {
+    if ( $reply->header->rcode eq 'NOERROR') {
+	say "Update succeeded" if($verbose);
+    } else {
+	say STDERR 'Update failed: ', $reply->header->rcode;
+	exit(1);
+    }
+} else {
+    say 'Update failed: ', $resolver->errorstring;
+    exit(1);
+}
+
+exit(0);
+
+__END__
+=head1 NAME
+
+sshdyndns - update A records based on ssh origin ip
+
+=head1 SYNOPSIS
+
+dnsupdate_tlsa [options] zone dnsname
+
+ Options:
+    -help	brief help message
+    -verbose	verbose output
+    -server	DNS server
+    -port	DNS port
+    -tsigname	Name of tsig key
+    -tsigkey	tsig key
+
+=head1 OPTIONS
+
+=over 8
+
+=item B<-help>
+
+Print a brief help message and exits.
+
+=item B<-server>
+
+DNS server to send DNS updates to.
+
+=item B<-port>
+
+DNS port to send DNS updates to, default 53.
+
+=back
+
+=head 1 DESCRIPTION
+
+B<This program> will update A records.
+
+=head1 ENVIRONMENTS
+
+=item B<SSH_CLIENT>
+
+Remote IP to set A record to.
+
+=back
+
+=cut