Change dhcp-client-identifier

[perl-list]

If you have foreknowledge of the MAC address, you could assign static IP based on the mac address like so: 

host SomeHost { hardware ethernet 00:01:02:03:04:05; fixed-address 10.0.10.2; } 

which would then make it not matter what their dhcp-client-identifier is... 

> From: "Thomas Zenz" <thomas.zenz at oenb.at>
> To: dhcp-users at lists.isc.org
> Sent: Wednesday, November 23, 2016 7:08:55 AM
> Subject: Change dhcp-client-identifier

> Sorry, I did not get the answer via mail, so I resend the Mail like this:

> Hi Patrick,

> I agree with you, that DHCP is not the cause of the issue. But, as
> allways, we are the ones who can fix it ;) Can we?

> We do have more VPN clients. That's why we had to look into this problem.

> Regards
> Thomas

> ###################################################

> It sounds like something changed recently - new VPN appliance? More VPN
> clients?

> It might be useful to include that in the conversation because it
> doesn't sound like ISC DHCP is the cause of the issue, just where it's
> become visible.

> Patrick

> ###################################################

> 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

> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
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