Multiple chrooted dhcp servers for vlans on Linux?

Muhammad Faisal faisalusuf at
Fri Feb 26 20:39:05 UTC 2016

  In case of different subnets on single interface the relay agents is a 
mandatory requirement. You can then segregate subnets per agent IP in 
the dhcp scope.

Relay agent IP is option routers in dhcpd


------ Original Message ------
From: "Chuck Anderson" <cra at WPI.EDU>
To: dhcp-users at
Sent: 2/27/2016 1:22:23 AM
Subject: Re: Multiple chrooted dhcp servers for vlans on Linux?

>This won't work unless you use separate full virtual machines...
>You could make it work on a single machine maybe, but you'd need to
>recompile the dhcpd with USE_SOCKETS.  Then dhcpd will only work to
>serve remote clients via a relay agent, not local clients directly
>connected to the same VLAN as the server.  This is because local
>clients must be served via a raw socket rather than a normal udp
>socket.  The reason is that responses to local, on-link clients must
>contain specific IP headers and MAC address headers that cannot be set
>via a regular udp socket, such as the all-ones broadcast address.  I
>may have the exact details wrong, but that is the gist of it.
>On Fri, Feb 26, 2016 at 10:51:41AM -0800, stevel_isc at wrote:
>>  The goal is to have multiple chrooted dhcpd processes, one for each 
>>of four
>>  vlans, such that a compromise of a more public one won't affect a 
>>  private one.
>>  Server version is isc-dhcpd-4.3.3-P1 and Linux is a recent install of
>>  Debian.
>>  I've got them all running but looking at dhcpd processes in netstat I 
>>  think it'll actually work in practice.
>>  Even though each one is specified to a particular vlan interface they 
>>  appear to be listening to and I see nothing visible 
>>  them.
>>  Are they really all listing on every vlan, and does that mean 
>>  requests over one vlan will be handled by whatever server happens to 
>>  the request (3 out of 4 chance it's the wrong one)?
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