One for the guild of networkers

Network isolation is the topic of the day how do you run two DHCP servers on a network without conflicts?

For example we currently have a router connected to a SME server which hands out I.P for the main network.

I want to setup a Clonezilla server however obviously I wish to avoid I.p Addy conflicts as the clonezilla would need to issue DHCP requests.

Now I am not a networking ninja our network setup isn't sophisticated I.e no subnets, vlans.

1) Could I setup a clonezilla server and connect it directly to a switch. Isolating it from the network completely. Could it in theory issue DHCP without a router.

2) Could I do the same as above but connect the switch directly to a router but not plug the router into our main network. Could DHCP be issued this way?

Any other ways to set this up completely isolating the secondary DHCP from the main DHCP.

Thank you guys

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Comments

Welly_59

Why does clonezilla have to dish out IP?

ally_uk

Pxe boot clients in order for the machines to touch base with server they meed a ip.

Nik 99

I'm kinda confused, why do you think you need a router to deal with DHCP? Thats not a routers job.

Simplest way to do this would be to just connect everything to a seperate switch if you have 1. Then setup a second dhcp along side that clonezilla server. You'd only need a router in this mix if you wanted this network to pass traffic to your main network or the internet.

ally_uk

So if a server is connected to a switch directly and I enable the DHCP service on the server. Anything I plug into that switch would get a I.p address. Bearing in mind there would be no outside network connection it's purely a server being linked to a switch.

Nik 99

ally_uk wrote: »

So if a server is connected to a switch directly and I enable the DHCP service on the server. Anything I plug into that switch would get a I.p address. Bearing in mind there would be no outside network connection it's purely a server being linked to a switch.

Yep, correct. Any host that is set to retrieve it's IP info from a dhcp server will do just that on this network.

This clonezilla sounds like a pain btw =P

ally_uk

The server won't be connected to a network though it has one Ethernet card connected directly to a switch.

I want to isolate it from the main network.

Are you sure DHCP would work? When you have to specify DNS information what should I do? Leave it blank or use the servers I.P

Nik 99

DHCP will work just fine. Why do you think it wouldn't?

You can leave DNS blank. Your not going to be resolving host names so you don't need it. You also don't need to define a default gateway (AKA the router) as you don't want your traffic to leave that network anyway.

ally_uk

Not sure dude I'm not very good at networking. I just always thought you had to have a server connected to a network / router to issue DHCP.

I'm going with clonezilla because I work for a charity that refurbished computer's we had 60 dells come in the other day figured I'd prep one and multicast deploy the image using clonezilla to the rest. I need the setup to be isolated from the main network to avoid DHCP conflicts with the main router.

Nik 99

By the way, if clonezilla must use multicast to get the job done then your switch needs to be multicast capable too. Not all switchs are, check your model supports IGMP (multicast).

ally_uk

Thanks for the heads up I shall have to dig one out.

dontstop

If possible I would say keep the cloning network separate from the production network. The last thing you want is to have a user machine which is configured to PXE boot start up and confuse the user or potentially begin the cloning process.

Grab yourself a cheap Gigabit switch from eBay like this and keep everything isolated!

ally_uk

I really need some help guys this whole thing is giving me a flipping headache

I will outline how far I have got so far and what is causing me a issue.

I have installed the Ubuntu Server 16:10 and setup the required packages for DRBL (clonezilla) The server was initially hooked up to main network for internet use so I could pull down and install required packages and update the system.

I have the server connected directly to a isolated switch. Currently this is the only node being connected to the switch can I connect it to any port on the switch? or am I being a numpty and should be aiming for a specific port.

The Server is currently not getting an i.p address so I figured I manually would have to setup one? what should my network config look like? just a i.p address as there is no gateway, dns,

The second bit which is stumping me is during the setup of DRBL I am specifically being asked for a DHCP scope to issue or a DHCP server.
As the server is connecting directly to a switch I currently do not have any DHCP services.

As the ethernet on the server is just one card how do I go about setting up a DHCP setup for Ubuntu.

I need somebody to hold my hand on this I literally am sat here with a banging headache

*update*

I have configured a static i.p address for my ethernet for the server that is connected to the switch. Am I missing any details?

192.168.1.0
255.255.255.0
0.0.0.0 G/W
192.168.1.255 B/C

Many Thanks

ally_uk

So I am still struggling to get the server to hand out DHCP. I have posted up my config hoping some networking guru / Linux ninja can call me an asshat and help me understand where I am going wrong:

UBUNTU SERVER 16:10

[ /etc/network/interfaces]

# the loopback network interface
auto lo
iface lo inet loopback

#the primary network interface
allow-hotplug enp3s0
iface enp3s0 static
address 192.168.2.1
netmask 255.255.0
gateway 0.0.0.0
broadcast 192.168.2.255

( This is a single ethernet card being connected directly to a switch, no router involved)

[DHCP Settings]

[/etc/default/isc-dhcp-server]

I added my interface

#INTERFACES="enp0s3"

[dhcpd.conf]

default-lease time 6000;
max-lease-time 7200;

subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.2 192.168.2.15;
option subnet-mask 255.255.255.0
option broadcast address 192.168.2.255
}

Nik 99

lol, i just finished replying to your other thread. didn't even see you updated this one.

EDIT: Ah, so u did what I suggested and installed dhcp onto the same box. Any changes? Does clonezilla detect dhcp now?

I think the network settings look alright. Can you get a test client onto your network so you can do some connectivity tests? Ping your client and ping the server. Also if you can see if that client can recieve an IP address via dhcp too.

Tbh I blame clonezilla for all your troubles =P

albinorhino187

So, I basically did this at my old job using a FOG server instead of clonezilla. FOG had an IP on my prod network. Separate DHCP server handed out IPs for my prod network. But I needed my new machines to PXE boot to my FOG server. I then configured a DHCP option on the DHCP server to define the PXE boot server, which was the IP of my FOG server. So any machines that were assigned an IP from my DHCP server would talk to my FOG server when PXE booting, and otherwise they'd boot from their HDD after they were imaged.