323 lines
7.6 KiB
Perl
Executable File
323 lines
7.6 KiB
Perl
Executable File
#! /usr/bin/perl
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use IO::Socket::INET;
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use Time::HiRes qw(gettimeofday sleep);
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use Getopt::Long;
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Getopt::Long::Configure("bundling");
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Getopt::Long::Configure("pass_through");
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$::USAGE = "Usage: detect_dhcpd -i interface [-m macaddress] [-t timeout] [-V]
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This command can be used to detect the dhcp server in a network for a specific mac address.
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Options:
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-i interface: The interface which facing the target network.
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-m macaddress: The mac that will be used to detect dhcp server. Recommend to use the real mac of the node that will be netboot. If no specified, the mac of interface which specified by -i will be used.
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-t timeout: The time to wait to detect the dhcp messages. The default value is 10s.
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Author: Wang, Xiao Peng\n";
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if (!GetOptions(
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'i=s' => \$::IF,
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'm=s' => \$::MACADD,
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't=s' => \$::TIMEOUT,
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'V|verbose' => \$::VERBOSE,
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'h|help' => \$::HELP,)) {
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print $::USAGE;
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exit 1;
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}
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if ($::HELP) { print $::USAGE; exit 0; }
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my $nic;
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if ($::IF) {
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$nic = $::IF;
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} else {
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print $::USAGE;
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exit 1;
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}
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my $start = Time::HiRes::gettimeofday();
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$start =~ s/(\d.*)\.(\d.*)/$1/;
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if (!$nic) { print "specify a nic\n"; print $::USAGE; exit 1;}
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#my $IP = `ifconfig $nic | grep "inet addr" | awk '{print \$2}' | awk -F: '{print \$2}'`;
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my $IPADDRMASK = `ip addr show dev $nic | grep inet | grep -v inet6 | awk '{print \$2}' | head -n 1`;
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my ($IP,$MASK)= split (/\//,$IPADDRMASK);
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my $MAC;
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my $tmpMAC;
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my @ipoutput;
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if ($::MACADD) {
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$MAC = $::MACADD;
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} else {
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# $MAC = `ifconfig $nic | grep "HWaddr" | /usr/bin/awk '{print \$5}'`;
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$tmpMAC = `ip link show $nic | grep ether`;
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@ipoutput= split (' ',$tmpMAC);
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$MAC=$ipoutput[1];
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}
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chomp($IP);
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chomp($MAC);
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if ($::VERBOSE) {
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print "Send out dhcp discover from: NIC = $nic, IP = $IP, MAC = $MAC\n";
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}
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if (!$IP || !$MAC) { print "Cannot find IP/MAC\n"; exit 1;}
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# check the distro
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my $os;
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if (-f "/etc/redhat-release") {
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$os = "rh";
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} elsif (-f "/etc/SuSE-release") {
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$os = "sles";
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} else {
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print "Only support the redhat and sles OS.\n";
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exit 1;
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}
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# fork a process to capture the packet by tcpdump
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my $pid = fork;
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if (!defined $pid) { print "Fork failed.\n"; exit 1;}
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my $dumpfile = "/tmp/dhcpdumpfile.log";
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if ($pid == 0) {
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# Child process
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my $cmd = "tcpdump -i $IF port 68 -n -vvvvvv > $dumpfile 2>/dev/null";
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`$cmd`;
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exit 0;
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}
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# generate the discover package
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my $package = packdhcppkg($MAC);
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# send out the package
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my $sock = IO::Socket::INET->new(Proto => 'udp',
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Broadcast => 1,
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#ReusePort => 1,
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PeerPort => '67',
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#LocalAddr => 0,
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LocalAddr => $IP,
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LocalPort => '68',
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PeerAddr => inet_ntoa(INADDR_BROADCAST));
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unless ($sock) {
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print "Create socket error: $@\n";
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kill_child();
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exit 1;
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}
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my $timeout = 10;
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if ($::TIMEOUT) {
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$timeout = $::TIMEOUT;
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}
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my $end = Time::HiRes::gettimeofday();
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$end =~ s/(\d.*)\.(\d.*)/$1/;
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while ($end - $start <= $timeout) {
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$sock->send($package) or die "Send discover error: $@\n";
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sleep 2;
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$end = Time::HiRes::gettimeofday();
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$end =~ s/(\d.*)\.(\d.*)/$1/;
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}
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kill_child();
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#kill the child process
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kill 15, $pid;
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my @pidoftcpdump = `ps -ef | grep -E "[0-9]+:[0-9]+:[0-9]+ tcpdump -i $IF" | awk -F' ' '{print \$2}'`;
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foreach my $cpid (@pidoftcpdump) {
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kill 15, $cpid;
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# print "try to kill $cpid\n";
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}
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sleep 2;
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open (FILE, "<$dumpfile") or die "Cannot open $dumpfile\n";
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my %output;
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my @snack = ();
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my @siaddr = ();
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my $newsection = 0;
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my $offer = 0;
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$chaddr = ();
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$ciaddr = ();
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$siaddr = ();
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while (<FILE>) {
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$line = $_;
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if ($line =~ /^\d\d:\d\d:\d\d/) {
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# A new packet was captured. Parse the last one.
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if ($::VERBOSE) {
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print "The server I found: mac = $chaddr, clientip = $ciaddr, serverip = $siaddr, offer = $offer.\n";
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}
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if ($os == "sles") { $offer = 1;}
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if ($chaddr =~ /$MAC/i && $offer && $ciaddr && $siaddr && $rsiaddr) {
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$output{$rsiaddr}{'client'} = $ciaddr;
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$output{$rsiaddr}{'nextsv'} = $siaddr;
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} elsif ($nack && $siaddr && !grep(/^$siaddr$/, @snack)) {
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push @snack, $siaddr;
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} elsif ($siaddr && ! grep(/^$siaddr$/,@server)) {
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push @server, $siaddr;
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}
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$offer = 0;
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$nack = 0;
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$chaddr = ();
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$ciaddr = ();
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$siaddr = ();
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$rsiaddr = (); # the server which responsing the dhcp request
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}
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if ($line =~ /(\d+\.\d+\.\d+\.\d+)\.[\d\w]+ > \d+\./) {
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$rsiaddr = $1;
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}
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if ($line =~ /\s*DHCP-Message.*: Offer/) {
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$offer = 1;
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} elsif ($line =~ /\s*DHCP-Message.*: NACK/) {
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$nack = 1;
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}
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if ($line =~ /\s*Client-Ethernet-Address (..:..:..:..:..:..)/) {
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$chaddr = $1;
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}
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if ($line =~/\s*Your-IP (\d+\.\d+\.\d+.\d+)/) {
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$ciaddr = $1;
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}
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if ($line =~/\s*Server-IP (\d+\.\d+\.\d+.\d+)/) {
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$siaddr = $1;
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}
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}
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close(FILE);
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my $sn = scalar(keys %output);
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print "\n++++++++++++++++++++++++++++++++++\n";
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print "There are $sn servers reply the dhcp discover.\n";
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foreach my $server (keys %output) {
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print " Server:$server assign IP [$output{$server}{'client'}] to you. The next server is [$output{$server}{'nextsv'}]!\n";
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}
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print "++++++++++++++++++++++++++++++++++\n\n";
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if (scalar(@snack)) {
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print "===================================\n";
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print "The dhcp servers which sending out NACK in present network:\n";
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foreach my $nack (@snack) {
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print " $nack\n";
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}
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}
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if (scalar(@server)) {
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print "===================================\n";
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print "The dhcp servers in present network:\n";
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foreach my $s (@server) {
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print " $s\n";
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}
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}
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#`rm -f $dumpfile`;
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exit 0;
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sub packdhcppkg{
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my $mymac = shift;
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my $package;
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# add the operation type. 1 - request
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$package .= pack("C*",1);
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# add the hardware type. 1 - ethernet
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$package .= pack("C*",1);
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# add the length of hardware add
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$package .= pack("C*",6);
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# add the hops
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$package .= pack("C*",0);
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# add the transaction id
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$package .= pack("C*",60,61,62,63);
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# add the elapsed time
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$package .= pack("C*",0,0);
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# add the flag 00 - broadcast
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$package .= pack("C*",128,0);
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# add the IP of client
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$package .= pack("C*",0,0,0,0);
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# add the your IP
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$package .= pack("C*",0,0,0,0);
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# add the next server IP
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$package .= pack("C*",0,0,0,0);
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# add the relay agent IP
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$package .= pack("C*",0,0,0,0);
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# add the mac address of the client
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my @macval;
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if ($mymac) {
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my @strmac = split(/:/, $mymac);
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foreach (@strmac) {
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push @macval, hex($_);
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}
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$package .= pack("C*",@macval);
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} else {
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@macval = ('0','0','50','51','52','53');
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$package .= pack("C*",@macval);
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}
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# add 10 padding for mac
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my @macpad;
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foreach (1..10) {
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push @macpad, "0";
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}
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$package .= pack("C*",@macpad);
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# add the hostname of server
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my @hs;
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foreach (1..64) {
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push @hs, "0";
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}
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$package .= pack("C*",@hs);
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# add the file name
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my @fn;
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foreach (1..128) {
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push @fn, "0";
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}
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$package .= pack("C*",@fn);
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# add the magic cookie
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$package .= pack("C*",99,130,83,99);
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# add the dhcp message type. The last num: 1 - dhcp discover
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$package .= pack("C*",53,1,1);
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# add the client identifier
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$package .= pack("C*",61,7,1); #type, length, hwtype
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$package .= pack("C*",@macval);
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# add the parameter request list
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$package .= pack("C*",55,10); #type, length
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$package .= pack("C*",1,3,6,12,15,28,40,41,42,119);
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# add the end option
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$package .= pack("C*",255);
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# pad the package to 300
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@strpack = unpack("W*",$package);
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my $curleng = length($strpack);
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my @padding;
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foreach (1..35){
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push @padding, '0';
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}
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$package .= pack("C*",@padding);
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return $package;
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}
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sub kill_child {
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kill 15, $pid;
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my @pidoftcpdump = `ps -ef | grep -E "[0-9]+:[0-9]+:[0-9]+ tcpdump -i $IF" | awk -F' ' '{print \$2}'`;
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foreach my $cpid (@pidoftcpdump) {
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kill 15, $cpid;
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#print "try to kill $cpid\n";
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}
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}
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