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dhcp-release
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dhcp-release
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#!/usr/bin/perl
use strict;
# Written by Leif Sawyer <leif@gci.net> Dec 14, 1999
# A simple utility to remove a host leases from the dhcp
# lease file, by IP or ethernet. Removes ALL entries for
# either the IP given, or the ethernet host.
#
my($PathLeases) = "/var/dhcpd/dhcpd.leases";
my($mode) = "ip";
my($etherhost) = "00:90:27:3f:6f:32";
my($iphost) = "24.237.1.102";
my($date)=`/bin/date +'%Y%m%d%H%M%S'`; chop $date;
print "Freeing lease for host $iphost ($etherhost)\n";
`mv $PathLeases $PathLeases.$date` && die "Can't mv $PathLeases to $PathLeases.$date: $!\n";
open(LEASES, ">$PathLeases") || die "Cannot open $PathLeases for writing: $!\n";
open(OLD,"<$PathLeases.$date") || die "Cannot open $PathLeases.$date for reading $!\n";
$SIG{'QUIT'} = \&exit_handler;
$SIG{'INT'} = \&exit_handler;
$SIG{'ABORT'} = \&exit_handler;
$SIG{'HUP'} = \&exit_handler;
my($in_entry) = 0;
my($i) = 0;
my($line) = 0;
my($found) = 0;
my(%entry);
my($ip) = "";
while(<OLD>) {
chop;
if ($in_entry) {
if ( /^\}/ ) {
$in_entry = 0;
if ($found) {
print "Found entry for host $ip, freeing.\n";
$line = 0; $found = 0; next;
}
for ($i=0; $i ne $line; $i++) {
print LEASES $entry{$i} . "\n";
}
print LEASES "}\n"; $line = 0; next; # reset and loop again
}
# We're somewhere in the lease entry, so start storing the info
if (/^\thardware ethernet (\S+:\S+:\S+:\S+:\S+:\S+);$/) {
$found = 1 if ( ( $1 eq $etherhost) && ($mode eq "ethernet") );
}
$entry{$line++} = $_;
} else { # We're not in a lease entry
if (/^lease (\d+\.\d+\.\d+\.\d+) \{$/) {
$ip = $1;
$found = 1 if ( ( $ip eq $iphost ) && ( $mode eq "ip" ) );
$in_entry = 1; $entry{$line++} = $_ ; next;
} else {
print LEASES $_ . "\n";
}
}
}
exit(1);
# ---------------------------------------------------------------------------
# Handle an interrupt in processing
# ---------------------------------------------------------------------------
sub exit_handler {
print "caught QUIT signal, restoring old config...\n";
close(OLD);
close(LEASES);
unlink "$PathLeases" if "$PathLeases.$date";
`mv $PathLeases.$date $PathLeases` && die "Warning: Can't restore $PathLeases from $PathLeases.$date: $!\n";
exit(0);
}