Scan a subnet for valid hosts with perl script

This is perl script for Scan a subnet for valid hosts. if given hostname, will look at the 255 possible hosts on that net. Report if host is running rexd or ypserv.

#!/usr/local/bin/perl -s
#
#
# Usage: scan n.n.n.n

# mine, by default
$default = "130.80.26";

$| = 1;

if ($v) { $verbose = 1; }

if ($#ARGV == -1) { $root = $default; }
else { $root = $ARGV[0]; }

# ip address
if ($root !~ /[0-9]+\.[0-9]+\.[0-9]+/) {
($na, $ad, $ty, $le, @host_ip) = gethostbyname($root);
($one,$two,$three,$four) = unpack('C4',$host_ip[0]);
$root = "$one.$two.$three";
if ($root eq "..") { die "Can't figure out what to scan...\n"; }
}

print "Subnet $root:\n" if $verbose;
for $i (01..255) {
print "Trying $root.$i\t=> " if $verbose;
&resolve("$root.$i");
}

#
# Do the work
#
sub resolve {

local($name) = @_;

# ip address
if ($name =~ /[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/) {
($a,$b,$c,$d) = split(/\./, $name);
@ip = ($a,$b,$c,$d);
($name) = gethostbyaddr(pack("C4", @ip), &AF_INET);
}
else {
($name, $aliases, $type, $len, @ip) = gethostbyname($name);
($a,$b,$c,$d) = unpack('C4',$ip[0]);
}

if ($name && @ip) {
print "$a.$b.$c.$d\t$name\n";
system("if ping $name 5 > /dev/null ; then\nif rpcinfo -u $name 100005 > /dev/null ; then showmount -e $name\nfi\nif rpcinfo -t $name 100017 > /dev/null ; then echo \"Running rexd.\"\nfi\nif rpcinfo -u $name 100004 > /dev/null ; then echo \"R
unning ypserv.\"\nfi\nfi");
}
else { print "unable to resolve address\n" if $verbose; }

}

sub AF_INET {2;}