脚本功能：通过ICMP Ping或TCP/SYN探测指定的域名，探测前检测域名是否有效。

file: check.host.pl#!/usr/bin/perluse strict;use Net::Ping;use Net::DNS;use Time::HiRes qw();$| = 1;my $DEFAULT_TIMEOUT = 2;my $PING_TIMEOUT = 2;my $DNS_TIMEOUT = 3;### 查询域名是否有效sub queryDomain { my $domain = shift(); my $query = ''; my $dns = Net::DNS::Resolver->new( tcp_timeout => $DNS_TIMEOUT, udp_timeout => $DNS_TIMEOUT, retry => 1 ); my @nameservers = qw/8.8.8.8 114.114.114.114/; $dns->nameservers(@nameservers); eval { $query = $dns->search($domain,'A'); }; if ($@ or ! $query) { my $err = $dns->errorstring ; print "ERR: query $domain failed: $errn"; return if ($err =~ /NXDOMAIN/); } return 'OK';}### return nothing is FAILED, other is OKsub pingHost { my $arg = shift(); return 1 if (ref $arg ne 'HASH'); my $p; eval { $p = Net::Ping->new($arg->{'proto'},$DEFAULT_TIMEOUT,0) }; if ($@) { warn "ERR to create Net::Ping object: $@n"; return; } $p->hires(); my ($host,$duration,$hip,$rep,$ret); ### tcp/syn ping if ($arg->{'proto'} eq "syn") { $p->{port_num} = $arg->{'port'}; $p->ping($arg->{'host'},$PING_TIMEOUT); if (($host,$duration,$hip) = $p->ack()) { printf("ACK Reply from $arg->{'host'}[%s] time=%.2f msn", $hip, $duration * 1000); $ret = 'OK'; } else { warn "SYN Request for $arg->{'host'} timed out.n"; } } ### icmp ping else { ($rep,$duration,$hip) = $p->ping($arg->{'host'},$PING_TIMEOUT); if ($rep) { printf("Echo Reply from $arg->{'host'}[%s] time=%.2f msn", $hip, $duration * 1000); $ret = 'OK'; } else { warn "PING Request for $arg->{'host'} timed out.n"; } } $p->close; undef($p); return $ret;}my $ARG = { proto => 'syn', port => 80 };my $host = $ARGV[0];my $proto = $ARGV[1];die "Usage: $0 [icmp]n" if (! $host);$ARG->{'host'} = $host;$ARG->{'proto'} = $proto if ($proto);my $code;if (&queryDomain($host) eq 'OK' and $code = &pingHost($ARG)) { print "$host is online !n";}else { print "$host is DOWN !n";}

测试例子：

# ./check.host.pl 2013.jb51.netERR: query 2013.jb51.net failed: NXDOMAIN2013.jb51.net is DOWN !# ./check.host.pl is DOWN !