routeros-scripts/dhcp-to-dns

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#!rsc
# RouterOS script: dhcp-to-dns
# Copyright (c) 2013-2019 Christian Hesse <mail@eworm.de>
#
# check DHCP leases and add/remove/update DNS entries
:global CharacterReplace;
:global Identity;
:global Domain;
:global HostNameInZone;
:local Zone;
:if ($HostNameInZone = true) do={
:set Zone ("dhcp." . $Identity . "." . $Domain);
} else={
:set Zone ("dhcp." . $Domain);
}
:local Ttl 5m;
:local CommentPrefix "managed by dhcp-to-dns for ";
:foreach Static in=[ / ip dns static find where comment ~ $CommentPrefix ] do={
:local MacAddress [ $CharacterReplace [ / ip dns static get $Static comment ] $CommentPrefix "" ];
:local IpAddress [ / ip dns static get $Static address ];
:local HostName [ / ip dns static get $Static name ];
:if ([ / ip dhcp-server lease print count-only where mac-address=$MacAddress address=$IpAddress dynamic=yes ] > 0) do={
:log debug ("Lease for " . $MacAddress . " (" . $HostName . ") still exists. Not deleting DNS entry.");
} else={
:local Found false;
:log info ("Lease expired for " . $MacAddress . " (" . $HostName . "), deleting DNS entry.");
/ ip dns static remove $Static;
}
}
:foreach Lease in=[ / ip dhcp-server lease find where dynamic=yes ] do={
:local Mac [ / ip dhcp-server lease get $Lease mac-address ];
:local DhcpIp [ / ip dhcp-server lease get $Lease address ];
:local Comment ($CommentPrefix . $Mac);
:local HostName [ $CharacterReplace [ / ip dhcp-server lease get $Lease host-name ] " " "" ];
:if ($HostName = "") do={
:set HostName [ $CharacterReplace [ / ip dhcp-server lease get $Lease mac-address ] ":" "-" ];
}
:local Fqdn ($HostName . "." . $Zone);
:local DnsNode [ / ip dns static find where name=$Fqdn ];
:if ([ :len $DnsNode ] > 0) do={
:local DnsIp [ / ip dns static get $DnsNode address ];
:local Leases [ / ip dhcp-server lease find where host-name=$HostName dynamic=yes ];
:local HostNameCount [ / ip dhcp-server lease print count-only where host-name=$HostName dynamic=yes ];
:if ($HostNameCount > 1) do={
:foreach J,Lease in=$Leases do={
:if ($J + 1 = $HostNameCount) do={
:set DhcpIp [ / ip dhcp-server lease get $Lease address ];
}
}
}
:if ($DnsIp = $DhcpIp) do={
:log debug ("DNS entry for " . $Fqdn . " does not need updating.");
} else={
:log info ("Replacing DNS entry for " . $Fqdn . ", new address is " . $DhcpIp . ".");
/ ip dns static set name=$Fqdn address=$DhcpIp ttl=$Ttl comment=$Comment $DnsNode;
}
} else={
:log info ("Adding new DNS entry for " . $Fqdn . ", address is " . $DhcpIp . ".");
/ ip dns static add name=$Fqdn address=$DhcpIp ttl=$Ttl comment=$Comment;
}
}