Change dhcp-client-identifier
Thomas Zenz
thomas.zenz at oenb.at
Fri Nov 18 16:22:35 UTC 2016
Dear all,
We are running isc dhcp for years now.
In the last weeks the count of vpn clients is growing. We only planned a
/24 network. That would be ok if there wasn't the cisco logic of
creating the dhcp-client-identifier. Cisco takes his own Mac-address,
adds the PCName and here comes the problem, a random number...
So my Client uses 17 Leases!
I reduced the lease-time to 1h but still, if a usere reconnects 3 times
in one hour, it uses 3 addreses.
uid "\000cisco-881d.fc6f.affe-NB326973851-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973852-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973857-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973858-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973861-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973863-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973848-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973850-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973853-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973854-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973873-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973859-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973865-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973866-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973868-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973869-inside\000";
uid "\000cisco-881d.fc6f.affe-NB326973870-inside\000";
I tried to change the uid like this:
on commit {
set myClientID = pick (option dhcp-client-identifier,0);
log (info, concat ("ClientID: ",myClientID));
but it looks like the option is no string...
(from the log)
dhcpd: ClientID: HPs2,
dhcpd: ClientID: HPs2,
dhcpd: ClientID: fÚAi
dhcpd: ClientID: HPsY
dhcpd: ClientID: HPsW¬
dhcpd: ClientID: lbmw&
dhcpd: ClientID: lbmw&
dhcpd: ClientID: HPsY
dhcpd: ClientID: HPsY
dhcpd: ClientID: HPsY
dhcpd: ClientID: HPsY
dhcpd: ClientID: HPs3T
dhcpd: ClientID: HPsW¬
dhcpd: ClientID: HPsW¬
dhcpd: ClientID: HPs\
dhcpd: ClientID: HPs\
I tried to do it like this:
if (binary-to-ascii(10,8,".",packet(24,3)) = "192.168.1" ) {
set vpnClientID = concat(substring(myClientID,26,6),"-inside");
set dhcp-client-identifier = vpnClientID;
log (info, concat ("vpnClientID: ",vpnClientID));
}
This is also not working. I use a similar option to choose the PXE Bootfile.
Please help
Kind Regards
Thomas
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