Author Topic: Network Setup /w manual IP's vs DHCP  (Read 1094 times)

Martinus

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Network Setup /w manual IP's vs DHCP
« on: September 06, 2008, 11:45:23 am »
Hi out there,

I'm new to LinuxMCE concept, software and idea.
My knowledge in computing is usable (programming, setting up PC's etc.) and I'm a technician,
but I have my blank spots.

I'm going to set up a hybrid with LinuxMCE RC2  into my home network.
I'd like to use it as a media center rather than for security/house service purposes,
that might add later.

my current network
1 PC W2K, 1 PC WinXP/Ubuntu 8.02, 1PC Ubuntu 8.02, 1 Laptop WinXP, one IP camera at the front door
This connects via cabling and switches in short range and via  powerLAN Network (which is slowly, but the cabling...) throughout the house and to a router as the gateway to the ADSL modem.
This setup uses fix IP's.

As I get deeper into LinuxMCE (reading, not doing, I'm just now setting up
the machine designated to be the hybrid) quite some questions show up :^)

1)
As I understand the supposed networking concept:
I'll go, throw out the router (in front of the ADSL modem) and connect the hybrid
directly to ADSL via the "external" NIC.
The existing network will be connected entirely to the "internal" NIC and the hybrid routes all internet connections.
Did I get that concept correct?

2)
Instead of using DHCP I'd like to set up fix IP's manually for all  devices that might add to the internal network (as I do currently).
I read already that it is possible to switch off DHCP but consequently it must be possible to setup IP's manually.
Does LinuxMCE allow for that (I'd wonder if not) and is that easily achieved (by a wizzard for instance)?
(I'm lazy)

3)
I believe (do not know) that most devices that might add to the internal network
can have their IP set up manually.
Is there any reason, that DHCP is mandatory?
(I can do without PnP in terms of finding a new device and set the new "connection" up manually)

4)
When distributing fix IP's to the networking devices (including the hybrid):
Does the router within LinuxMCE act like the router I used up to now ?
(Build IP-Maps and recognizes which IP goes where -a real blind spot of mine-)

5)
I try to install LinuxMCE without  the machine  being connected to the network or the Internet.
Does that work or does the machine have to be connected to the Internet and/or the internal network while installation?

Why do I want to run it that way:
I'd like to have control on what happens on the network.
I run Zonelalarm on the Windows PC's so I can control which program has access to the internet (Never trust Windows) but here working with fixed IP's makes it a lot easier.
Games we play via network need fixed IP's to identify the pc's involved.
I am doing the setup at work, where I have room but no internet.


thanks a lot in advance.

Martin

A lot or read for you :^)
LinuxMCE looks like it is real exciting  stuff,
I even might get back to programming and look deeper into Linux.

colinjones

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Re: Network Setup /w manual IP's vs DHCP
« Reply #1 on: September 06, 2008, 12:58:40 pm »
The short answer to most of your questions is: do not set IPs statically. You haven't actually given any real reason why you want to do this anyway, so all the more reason not to do it. But basically, the system uses DHCP for several reasons, one of which is pnp as you say - you do not want to try to set devices up manually, esp if you have holes in your LMCE knowledge (and networking knowledge, which you mentioned).

One significant reason is, if you have problems (which you probably will as you are re-engineering the system) you will not get much sympathy on the forums if your first step was to change the design :)

There are almost no meaningful reasons not to use DHCP. The only one that some people get hung up on are you may have fixed firewall rules port forwarding to specific IP addresses or the like - but this doesn't really hold up, because once LMCE has assigned an IP address, under normal circumstances it will never change 1) because the client will continually request a renewal of the same address and 2) because LMCE records the MAC address of the client's NIC and always had out the same address anyway. So they effectively become fixed addresses anyway.

1) You don't have to throw out the router if you don't want to. That's up to you - but it is true you won't actually need it anymore (are you sure the ADSL modem isn't a router anyway, most are, in which case you never needed it anyway). Yes, under normal circumstances your entire existing network would be behind the LMCE core/hybrid on the "internal" network.

3) I have never come across a device (in many years, at least) that does not support DHCP.

4) The core/hybrid acts just like any other router except that it has a firewall on it so for certain things you may need to set up firewall rules. In short, a router doesn't set up "IP maps" it has "routes" that describe entire subnets (eg 192.168.80.0/24) is reached through interface X, via gateway Y. There will always be a "default route" or "route of last resort" that tells it where to send traffic that doesn't match any of the other, more specific routes. Essentially, your core will have 3 main routes, one that says 192.168.80.0/24 subnet is out the "internal" NIC, one that says your external subnet (something like 192.168.1.0/24) is out the external NIC, and one that says all other subnets are out the external NIC via the internal IP address of your modem/router.

5) Definitely set up with Internet access, it will make several things easier/possible. After you have installed, you don't need to maintain that Internet access if you don't want to.

Martinus

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Re: Network Setup /w manual IP's vs DHCP
« Reply #2 on: September 09, 2008, 07:19:19 pm »

Hi Colin,

thanks for reply.
Couldn't get back earlier.
You haven't actually given any real reason why you want to do this anyway, so all the more reason not to do it.

Further down the post you mention it. Static IP for Firewall reasons.
I checked my system and found a way to set a window within zonealarm and the router currently sets IP's within this range, so I think I can live with DHCP.

Well,
One significant reason is, if you have problems (which you probably will as you are re-engineering the system) you will not get much sympathy on the forums if your first step was to change the design :)

This looks to me a bit hmm.. unlinux like.
But as far as I get down the line in installing I had first contact with the setup wizard and it is quite unusual having a system talking to me.
What an effort..great.
I'm really not used to simple systems for the common user.

The only one that some people get hung up on are you may have fixed firewall rules port forwarding to specific IP addresses or the like -
That's what I meant..

1) You don't have to throw out the router if you don't want to. That's up to you - but it is true you won't actually need it anymore (are you sure the ADSL modem isn't a router anyway, most are, in which case you never needed it anyway).

OK, no need to throw the router out.
Well, I had a combined ADSL modem/Router but with a recent change to ADSL2 I had to switch the modem and the provider selected one with no router built in so I had to attach one.

5) Definitely set up with Internet access, it will make several things easier/possible. After you have installed, you don't need to maintain that Internet access if you don't want to.

I just don't have an open internet access at the company so I just put the machine together and run the installation at home.
No sweat.

But what I wanted to know: Would LMCE update later when I connect it to the internet at home and update at that point, with the installation already done?
It seems somewhat inflexible to me if the system couldn't do that.

Thanks a lot again so far for sharing your thoughts.

all the best

Martin

colinjones

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Re: Network Setup /w manual IP's vs DHCP
« Reply #3 on: September 09, 2008, 11:59:57 pm »
On the unlinux point - once you start browsing the forums you'll see why, it has been discussed to death ... I'm trying to save you the pain. And as I say, the addresses don't end up being dynamic anyway, so it deals with your firewall rule issue anyway.

I'm not sure how much is dependent on an Internet connection during setup. Things like location finding, to set sunrise/set, etc are but you can always do that later. I would say that all the software is in the deb-caches or on the image-drop (for the DVD) but it is always possible that it might look for something else during setup... so to be safe...

As for updates, yes LMCE has an update system (and disables the normal Kubuntu one, as this is necessary to maintain specific dependencies) - at the moment, however, no updates are going out as the devs are in the process of merging 2 separate code trees. Once that is complete, the updates will start rolling again.

BTW - you will probably find there is a hack out there to enable the router functionality of your modem. There is usually a modem/router version of the hardware and they usually just hack the firmware to disable the router functionality in the modem only version of the hardware. Just a thought as it might make your network simpler..

Martinus

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Re: Network Setup /w manual IP's vs DHCP
« Reply #4 on: September 10, 2008, 07:45:00 pm »
Hi Colin and poeple,

On the unlinux point - once you start browsing the forums you'll see why...
I'm trying to save you the pain.

I thought that I might stress a theme that is already discussed at length,
but there is always a chance to have a different look at it.
Well, I don't want to upset anyone, just getting known to LMCE and I strongly appreciate your intentions.

I'm not sure how much is dependent on an Internet connection during setup. ... so to be safe...

...As for updates, yes LMCE has an update system...

I'll take my time, I think about going through the processes just for getting the feeling
If I end up with a problem because of updates I'll run the installation again.
I have to at least once anyway because I didn't add the second NIC inititally.
I was aware about the locked updates on Kubuntu, just not how necessary is an active internet connection at time of installation.

BTW - you will probably find there is a hack out there to enable the router functionality of your modem. ... Just a thought as it might make your network simpler..

Thanks, I will have a look at that.  :)

I thought that linux firewalls and linux itself is quite safe against hacking and viruses  ;D (one point is, so was I told, that routers provide a firewall that save Windows pc's (especially XP) from being overrun by viruses.

I don't need to share the ADSL modem directly to other pc's when I use LMCE as the router and the rest is behind that, otherwise I'd leave it as it is.
The modem has but one port, so there's is not much to route, especially when the LMCE is in between and a firewall might be the only issue to hack it.

Thanks so far  for your patience and insights

Greetings

Martinus

wsuetholz

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Re: Network Setup /w manual IP's vs DHCP
« Reply #5 on: September 11, 2008, 12:24:01 am »
One thing to note here, is that you can accomplish the fixed IP addresses with the LinuxMCE web administration, and DHCP.  Or, if you really don't want to have those machines doing DHCP.  Create the entry for the machine so that LinuxMCE knows about it, and won't assign that IP address to one of the PNP devices later on.

My current setup goes one further, and has 3 NICS.  One for Outside, one for Inside, and one for the TV Tuners.  I was having some issues watching live tv, so I thought having the tuners on one network by themselves might help.  HDHomeRun, Tuners..  Shows are copied over the network to the core, and then back out over the network to the remote frontend.

I also am not using the LinuxMCE firewall, instead I'm using Shorewall.  I was able to convince the LinuxMCE DHCP configuration to behave eventually.

As Colin said, doing a setup like this will eliminate most of the support from the list.  I know of some hardworking (stressed) developers that will be extremely rude, when being asked for support for non-standard(approved) configs.