[CentOS-virt] Question - Xen host, DHCPD and guest VMs

Scot P. Floess sfloess at nc.rr.com
Fri Nov 6 17:05:31 UTC 2009

So, to be honest this is running on my home network ;)  I'm not too 
worried about security - there is nothing sensitive on my network as is :)

Interesting, I never considered running a guest VM and it serving up dhcp 
addresses :D

So, one thing about my home network is my machines don't all have much 
RAM.  This particular machine has 1 GB and is my "administrative" 
server - DNS, NIS, NFS, etc...  I slivered off a small VM for a postgres 
DB and like it to start up when the machine boots.  I do, sometimes bring 
that down and bring up another VM...

I definitely understand what you mean though - but this isn't mission 
critical or anything so I don't mind it doing what its doing - it works 
fine to date by bouncing dhcpd - but I hate that ;)  I may try to get my 
cable modem-router to serve up dhcp - but I don't think it'll let me do 
ddns internally (that's another thing I am doing inside my network)...

On Fri, 6 Nov 2009, Christopher G. Stach II wrote:

> ----- "Scot P. Floess" <sfloess at nc.rr.com> wrote:
>> Anybody know what I need to do :)  I've been bouncing dhcpd in
>> /etc/rc.local and starting any VMs there.  Although annoying, I'd
>> rather
>> do it "right" so I can auto start my Xen guests...
> If you want to do it correctly, don't run dhcpd in domain 0. :) You're exposing your host to traffic that it doesn't need to deal with, which can be bad for performance and is bad for security. You're also putting one extra service there that isn't solely related to keeping the ground beneath the guests, the only thing domain 0 should be doing. Start a guest to run dhcpd in auto and name the sym link in auto something like "00-guestname" so it runs before the other guests. If you have two or more physical hosts and you run ISC dhcpd, run another one of these guests as a dhcp failover peer on another host.
> -- 
> Christopher G. Stach II
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> CentOS-virt at centos.org
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Scot P. Floess
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