$data = <<'DATA';
foo 1.1.1.1 foo
bar 22.22.22.22 bar
baz 333.333.333.333 baz
DATA

# this is *wrong*
foreach($data=~ /(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/g){
    push @ips, $1;
}

print "Foreach fails and gives:\n";
print "$_\n" for @ips;

@ips = ();

# this is right
while($data=~ /(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/g){
    push @ips, $1;
}

print "While works and gives:\n";
print "$_\n" for @ips;