as an alternative, you can bind a variable to the entry widget, e.g.

use vars qw($IpAddress);
my $entry = $parent->Entry(-textvariable => \$IpAddress)
  ->pack(-side => 'left');
$parent->Button(-text => 'Go', -command => \&DoIt)
  ->pack(-side => 'left');

sub DoIt {
  print "Entry contains: $IpAddress\n";
} # DoIt
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