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#1 2007-08-10 02:16:41

Jessehk
Member
From: Toronto, Ontario, Canada
Registered: 2007-01-16
Posts: 152

Some very "newbie" networking questions -- trying to get started

Hello all. Since this forum is so friendly for issues related to Arch, I thought I'd post my semi-arch related question. smile

I'm trying to create a network for my house, consisting of about 3 computers. I have a book reference, TCP/IP Network Administration from O'reilly, but I think I need a bit of a "kick-start" in order to get to a level in which I can comfortably understand the book (if that makes sense).

I've got internet access working by connecting to a router and having everything configured by DHCP (ie, in rc.conf, eth0="dhcp"). What's bothering me (and I don't even know if it should) is that the other computers on the physical network are not visible to me.

IE, when I try to connect to them with their host name, it doesn't recognise them. My understanding of that is that either I need to manually set the hostnames of the other computers on the network in /etc/hosts, or use something like a DNS server on one of the computers in the network in order to recognize the others.

My other doubt is that I think I've got a dynamic IP address (though it might be static, I'm not quite sure). Does that change things?

I don't expect you guys to completely run through me setting up the network (that's what the book is for!) but some basic advice on either my misconceptions (I'm sure I have plenty) or related in general to my situation would be awsome and highly appreciated. I'd also be happy to provide any additional info that would be helpful.

Thanks in advance. smile

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#2 2007-08-10 03:04:32

ralvez
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From: Canada
Registered: 2005-12-06
Posts: 1,694
Website

Re: Some very "newbie" networking questions -- trying to get started

OK, there are a few things here that you need to handle in order to get started.
1. If you use DHCP on a range of say 250 addresses, there is no way for you to know the address/name of any of those computers unless you have a machine to DNS the addresses that your DHCP server gives away.
So, since it is a small network ( and because to get yourself started you want something you can easily handle ) I would "promote" your machines to static addresses. That simple move will give you two things: (a) A simple way to identify each machine by address (b) an easy way to "name" each machine in your /etc/hosts file so that you can actually type something like "ping tester_1" or "ping 192.168.1.23" and know which machine should respond.
2. Set all your machines to see the router address, so you can experiment with web access from any of the machines.
3. Set SSH so you can manage the machines remotely.
4. Once you have the network reliably working then you can set up kerberos (or whatever you like) to handle log ins.

Hope this helps.

R.

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#3 2007-08-10 06:02:07

Jessehk
Member
From: Toronto, Ontario, Canada
Registered: 2007-01-16
Posts: 152

Re: Some very "newbie" networking questions -- trying to get started

Thanks for the advice. smile

If anything I'm about to say sounds really stupid, it's because I'm very new to this.

Assuming I don't update my to my ISP's static IP service (very expensive), is it still possible to connect the computers and use services such as NFS, Sambda, etc?

My understanding is that my gateway to the internet is my router, to which all of the computers in the network (3) connect. What I need on my zone is a master DNS server in order to assign hostnames to the IP addresses that are randomly assigned to the computers in my network. The other computers in the network can then page the master server  for the IP address associated with a hostname, or go through the gateway (my router) to the rest of the world (the internet). Therefore, the master server has to somehow download this database of IP-address-to-hostname mappings from the server that randomly assigns the IP addresses to the machines in my network. The book I have is unfortunately very terse in some cases and doesn't seem to mention what to do with IP addresses that are not static.

Do any of you know of any resources that help explain this sort of thing? Am I on the right track? Do I have the right idea of what needs to be done?

Last edited by Jessehk (2007-08-10 06:03:55)

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#4 2007-08-10 07:13:59

Mefju
Member
From: Poland
Registered: 2006-07-12
Posts: 104

Re: Some very "newbie" networking questions -- trying to get started

You can make that IP numbers in your network will be fixed and delivered by DHCP server at the same time. Read something about host directive in /etc/dhcpd.conf. It may look like this

host <hostname>
{
        hardware ethernet <mac address>;
        fixed-address <ip address assigned to host>;
}

So with this, host everytime gets the same IP.

Now, if you have static IP address from your ISP, you have to set up NAT to deliver web access to hosts in your network. If you have DSL connection with random assigned IP number, you have to use MASQERADE instad NAT.

I suggest that for now you should use /etc/hosts file for address translation. When your network will be working without problems, than you can switch to DNS. In my opinion using bind in network with 3 hosts is like shooting with big gun to mosquitos.

Good luck with setting up your network smile

Last edited by Mefju (2007-08-10 07:17:00)

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#5 2007-08-10 11:43:08

ralvez
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From: Canada
Registered: 2005-12-06
Posts: 1,694
Website

Re: Some very "newbie" networking questions -- trying to get started

I take you use Rogers or Sympatico, correct?
Well, in my case I use Rogers, and I  have not upgraded to static IP (I think they charge you as if you are a commercial entity in such case) and have my network at home. My point: you do not have to upgrade.

You can have samba, NFS, whatever it does not matter. You have what is called a "private network" and the IP address your ISP gives you is a "public IP address" (your book may describe this) so there is no problem there.

R.

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#6 2007-08-10 14:35:38

Jessehk
Member
From: Toronto, Ontario, Canada
Registered: 2007-01-16
Posts: 152

Re: Some very "newbie" networking questions -- trying to get started

ralvez wrote:

I take you use Rogers or Sympatico, correct?

I have Rogers Cable.
Could you go into a bit more detail about how you set things up? Do you use hostnames or IP addresses? I'm a bit confused. smile

I suggest that for now you should use /etc/hosts file for address translation. When your network will be working without problems, than you can switch to DNS. In my opinion using bind in network with 3 hosts is like shooting with big gun to mosquitos.

That was the impression I got too. Could I just use something like DynDNS in order to update my hostnames?

Last edited by Jessehk (2007-08-10 15:03:49)

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#7 2007-08-10 16:00:49

ralvez
Member
From: Canada
Registered: 2005-12-06
Posts: 1,694
Website

Re: Some very "newbie" networking questions -- trying to get started

My set up is simple.
I have a Linux router running on an old Pentium machine. It has two cards, one configured for the private network (with an address like 192.168.1.1) and the second card set up to take addresses from DHCP ( since that's how Rogers sends you the public address).
In that machine I run my firewall, SmoothWall (smoothwall.org) and have enabled NAT so the machines in the inside network can go to the Internet.

I have Samba set up in another machine to share files (that's an Arch system) with static IP, my daughter's machine (another Arch system), my system (obviously another Arch with static IP) and my wife's machine with Windows XP system (static IP too).

So, the key concept here  are:
1. Use static IPs for the private network
2. Use DHCP for Rogers
3. Use NAT in your router so all the machines can go to the Internet but no one from the Internet can get to them.

Hope this helps.

R

p.s. feel free to contact me off the list if you need further details/help.

Last edited by ralvez (2007-08-10 16:05:34)

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#8 2007-08-10 16:32:46

Jessehk
Member
From: Toronto, Ontario, Canada
Registered: 2007-01-16
Posts: 152

Re: Some very "newbie" networking questions -- trying to get started

ralvez wrote:

My set up is simple.
I have a Linux router running on an old Pentium machine. It has two cards, one configured for the private network (with an address like 192.168.1.1) and the second card set up to take addresses from DHCP ( since that's how Rogers sends you the public address).
In that machine I run my firewall, SmoothWall (smoothwall.org) and have enabled NAT so the machines in the inside network can go to the Internet.

I have Samba set up in another machine to share files (that's an Arch system) with static IP, my daughter's machine (another Arch system), my system (obviously another Arch with static IP) and my wife's machine with Windows XP system (static IP too).

So, the key concept here  are:
1. Use static IPs for the private network
2. Use DHCP for Rogers
3. Use NAT in your router so all the machines can go to the Internet but no one from the Internet can get to them.

Hope this helps.

R

p.s. feel free to contact me off the list if you need further details/help.

Aha! So, for example, the network 192.168.0.0 where mask is 255.255.255.0 is a private network set up by my router, right?

So the addresses in 192.168.0.0 never change, but the public IP address of the hosts do change?

Does that mean that if, for example, I have a host called 192.168.0.32 that its address never changes? Can I simply add that to all the other hosts' /etc/hosts file and it won't change?
All I was ever concerned about was allowing hosts in the network to contact each other via hostname. If that never changes then I'm all set.

BTW, thanks for your continuing help! smile

Last edited by Jessehk (2007-08-10 16:33:57)

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#9 2007-08-10 18:40:29

ralvez
Member
From: Canada
Registered: 2005-12-06
Posts: 1,694
Website

Re: Some very "newbie" networking questions -- trying to get started

Aha! So, for example, the network 192.168.0.0 where mask is 255.255.255.0 is a private network set up by my router, right?

This part is partly correct. A 192.168.x.x address belongs to a private class network (referred to, but now deprecated, as a class C network) but is not set up by the router, you give each machine in your LAN an address within that range. And BTW you cannot assign any machine the address 192.168.0.0 that address is reserved (there are a few others make sure to know about them).
Now this is not exactly correct:

So the addresses in 192.168.0.0 never change, but the public IP address of the hosts do change?

The private address, of course being private do not change. That is to say that the internal network (your LAN) addresses do not change but the public IP address of the card in the router, the one that connects to the Roger's box, does because it is managed by the DHCP server at Rogers.

Does that mean that if, for example, I have a host called 192.168.0.32 that its address never changes? Can I simply add that to all the other hosts' /etc/hosts file and it won't change?

You are absolutely correct about that.

R.

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#10 2007-08-10 19:02:21

Jessehk
Member
From: Toronto, Ontario, Canada
Registered: 2007-01-16
Posts: 152

Re: Some very "newbie" networking questions -- trying to get started

Everything works great now. I've got NFS setup and I'm probably going for SAMBA next. Thanks for the great help ralvez! smile

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#11 2007-08-10 23:25:42

ralvez
Member
From: Canada
Registered: 2005-12-06
Posts: 1,694
Website

Re: Some very "newbie" networking questions -- trying to get started

Glad to be of help.
Have fun!

R.

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