Geo::IP looks up country by IP Address, and from there you might be able to guess the time zone. There is both a free (gratis) and paid country database:

www.maxmind.com/app/geoip_country

use strict;
use warnings;

use Geo::IP;
use DateTime;
use DateTime::TimeZone;

my $gi = Geo::IP->new(GEOIP_STANDARD);
my $country_code = $gi->country_code_by_addr('24.24.24.24');
print qq{Country:\t$country_code};

my $dt = DateTime->now;
foreach my $tz (DateTime::TimeZone->names_in_country($country_code)) {
  $dt->set_time_zone( $tz );
  print $tz . qq{\t} . $dt->hms();
}
__END__
$ perl -l 630749.pl
Country:        US
America/New_York        04:19:57
America/Detroit 04:19:57
America/Kentucky/Louisville     04:19:57
America/Kentucky/Monticello     04:19:57
America/Indiana/Indianapolis    04:19:57
America/Indiana/Knox    03:19:57
America/Indiana/Winamac 04:19:57
America/Indiana/Marengo 04:19:57
America/Indiana/Vevay   04:19:57
America/Chicago 03:19:57
America/Indiana/Vincennes       03:19:57
America/Indiana/Petersburg      03:19:57
America/Menominee       03:19:57
America/North_Dakota/Center     03:19:57
America/North_Dakota/New_Salem  03:19:57
America/Denver  02:19:57
America/Boise   02:19:57
America/Shiprock        02:19:57
America/Phoenix 01:19:57
America/Los_Angeles     01:19:57
America/Anchorage       00:19:57
America/Juneau  00:19:57
America/Yakutat 00:19:57
America/Nome    00:19:57
America/Adak    23:19:57
Pacific/Honolulu        22:19:57
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