Confused about my home networking setup

Life used to be simple. I used to assign a static id in the 192.168.1.x
range to every box on my home LAN and I used two static id's for my
domain name server from my ISP, Comcast.

Then I got a message from Comcast, warning that I needed to change my
network settings to use DHCP and automatically get the dns
from the provider. That's when things started going haywire.

I have Linux boxes, Windows boxes, and Mac OS X boxes on my
home network. The Mac boxes were no problem at all. They kept
working like nothing changed. The Windows boxes are doing okay
as well, with some hiccups. The Linux boxes aren't faring well.
I'd appreciate any help in getting things back to normal.

Here's my setup: I have a cable modem taking the feed from Comcast.
That hooks to a Linksys wireless G router. The Linksys router has
a DHCP server built in. Since the Comcast change, I've allowed
the Linksys to hand out IP addresses and I've set all my clients
to get their IP addresses from DHCP.

The problem is, my Linux boxes can't find the other computers anymore.
I can't print at all (my printer is attached to a Windows box).
To use ssh, I need to log in to my Linksys router to find out
what IP addresses are leased. Then, while my Mac and Windows
boxes seem to be telling the DHCP server what their names are,
the Linux boxes aren't.

So here's my question:
How do I set up a dns functionality for my local LAN, so all
the machines know where each other are, even after their DHCP
leases expire and are reassigned? Can I just run my own dns server
and forget using Comcast's?

I'd rather run it on Windows or Mac, since I'm probably going to
phase out Linux in the near future. But running it on Linux in
the near term is possible.

Hamad bin Turki Salami wrote:
> Life used to be simple. I used to assign a static id in the 192.168.1.x
> range to every box on my home LAN and I used two static id's for my
> domain name server from my ISP, Comcast.
>
> Then I got a message from Comcast, warning that I needed to change my
> network settings to use DHCP and automatically get the dns
> from the provider. That's when things started going haywire.
>
> I have Linux boxes, Windows boxes, and Mac OS X boxes on my
> home network. The Mac boxes were no problem at all. They kept
> working like nothing changed. The Windows boxes are doing okay
> as well, with some hiccups. The Linux boxes aren't faring well.
> I'd appreciate any help in getting things back to normal.
>
> Here's my setup: I have a cable modem taking the feed from Comcast.
> That hooks to a Linksys wireless G router. The Linksys router has
> a DHCP server built in. Since the Comcast change, I've allowed
> the Linksys to hand out IP addresses and I've set all my clients
> to get their IP addresses from DHCP.
>
> The problem is, my Linux boxes can't find the other computers anymore.
> I can't print at all (my printer is attached to a Windows box).
> To use ssh, I need to log in to my Linksys router to find out
> what IP addresses are leased. Then, while my Mac and Windows
> boxes seem to be telling the DHCP server what their names are,
> the Linux boxes aren't.
>
> So here's my question:
> How do I set up a dns functionality for my local LAN, so all
> the machines know where each other are, even after their DHCP
> leases expire and are reassigned? Can I just run my own dns server
> and forget using Comcast's?
>
> I'd rather run it on Windows or Mac, since I'm probably going to
> phase out Linux in the near future. But running it on Linux in
> the near term is possible.
>
>
>
You are confusing two DHCP servers.

1. Your ISP uses DHCP to give the ISP interface of your router an IP
address.

2. Your router uses DHCP to give your local machines IP addresses.

You didn't have to use DHCP on your local net just because your ISP
didn't give you a fixed IP address. But if you do,

A. Your router, which hands out your local IP addresses, presumably has
DNS functionality as well. So your local machines use the router as
their DNS server. Don't worry about it: the DHCP protocol will tell them
where their DNS server is.

B. You can only see local machines that have active DHCP leases (if they
do not have fixed addresses). Your linux machines probably don't declare
their hostnames to DHCP by default so edit the file:

/etc/dhcp3/dhclient

(or something like it) suct that there is a line that says:

send host name myhost

(if the host name is myhost).

I hope that this helps.

Robert

Hamad bin Turki Salami <(E-Mail Removed)> writes:

>Life used to be simple. I used to assign a static id in the 192.168.1.x
>range to every box on my home LAN and I used two static id's for my
>domain name server from my ISP, Comcast.

Did they change the name servers? Remember, unless your ISP filters dns
queries you can use any dns server in the world. Your local one is probably
most convenient.


>Then I got a message from Comcast, warning that I needed to change my
>network settings to use DHCP and automatically get the dns
>from the provider. That's when things started going haywire.

Getting your IP and getting a dns are two separate issues. YOu can do one
without the other.


>I have Linux boxes, Windows boxes, and Mac OS X boxes on my
>home network. The Mac boxes were no problem at all. They kept
>working like nothing changed. The Windows boxes are doing okay
>as well, with some hiccups. The Linux boxes aren't faring well.
>I'd appreciate any help in getting things back to normal.

>Here's my setup: I have a cable modem taking the feed from Comcast.
>That hooks to a Linksys wireless G router. The Linksys router has
>a DHCP server built in. Since the Comcast change, I've allowed
>the Linksys to hand out IP addresses and I've set all my clients
>to get their IP addresses from DHCP.

>The problem is, my Linux boxes can't find the other computers anymore.

What is your routing table? And I have no idea why you needed to change
anything on your local lan. That has nothing to do with the external world.

>I can't print at all (my printer is attached to a Windows box).
>To use ssh, I need to log in to my Linksys router to find out
>what IP addresses are leased. Then, while my Mac and Windows
>boxes seem to be telling the DHCP server what their names are,
>the Linux boxes aren't.

AGain, why did you change things?


>So here's my question:
>How do I set up a dns functionality for my local LAN, so all
>the machines know where each other are, even after their DHCP
>leases expire and are reassigned? Can I just run my own dns server
>and forget using Comcast's?

Just assign static IPs on your router. Or have your router supply the same
IP to the same MAC address if you really want to use dhcp.


>I'd rather run it on Windows or Mac, since I'm probably going to
>phase out Linux in the near future. But running it on Linux in
>the near term is possible.

On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
> Life used to be simple. I used to assign a static id in the 192.168.1.x
> range to every box on my home LAN and I used two static id's for my
> domain name server from my ISP, Comcast.
>
> Then I got a message from Comcast, warning that I needed to change my
> network settings to use DHCP and automatically get the dns
> from the provider. That's when things started going haywire.
>
>
> So here's my question:
> How do I set up a dns functionality for my local LAN, so all
> the machines know where each other are, even after their DHCP
> leases expire and are reassigned? Can I just run my own dns server
> and forget using Comcast's?

Just tell your router to use dhcp from comcast.
You can run all your LAN PCs as static.
Put everyone's name/ip in everyone's host file.

Power down every thing, power up cable modem, wait for steady state on
leds, power up router. It will get a comcast dhcp lease. Now powwer up your
systems, Look around on your router and get the Comcast DNS values and put
them in all your PCs.

At this point you are "stret legal" as far as Comcast is conserned.

Now your only problem is keeping the PC's DNS values synced with the
ones handed out by Comcast.

On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
> Life used to be simple. I used to assign a static id in the 192.168.1.x
> range to every box on my home LAN and I used two static id's for my
> domain name server from my ISP, Comcast.
>
> Then I got a message from Comcast, warning that I needed to change my
> network settings to use DHCP and automatically get the dns
> from the provider. That's when things started going haywire.

Which I ignored -- and nothing untoward happened here.
I let them assign whatever IP addy they want to the cable modem.
I use a set of DNS IP's that are _not_ Comcast's -- both before and
after their 'dramatic' changes.
I run a LAN with 2 linux boxen, 2 OS/2 boxen, and my First Wife's
WinXP box -- using fixed LAN IP assignments.
Like I said, I received their dire warning -- ignored it -- and nothing
untoward happened here.

HTH
Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: <http//jonz.net/ng.htm>

On 2006-05-10, Allodoxaphobia <bit-(E-Mail Removed)> wrote:
> On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
>> Life used to be simple. I used to assign a static id in the 192.168.1.x
>> range to every box on my home LAN and I used two static id's for my
>> domain name server from my ISP, Comcast.
>>
>> Then I got a message from Comcast, warning that I needed to change my
>> network settings to use DHCP and automatically get the dns
>> from the provider. That's when things started going haywire.
>
> Which I ignored -- and nothing untoward happened here.
> I let them assign whatever IP addy they want to the cable modem.
> I use a set of DNS IP's that are _not_ Comcast's -- both before and
> after their 'dramatic' changes.
> I run a LAN with 2 linux boxen, 2 OS/2 boxen, and my First Wife's
> WinXP box -- using fixed LAN IP assignments.
> Like I said, I received their dire warning -- ignored it -- and nothing
> untoward happened here.

They weren't actually requiring that users use DHCP for their internal
home networks, were they? I find that hard to believe, but if so,
that reeks of ignorance/incompetence on Comcast's part.


--


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Jim Cochrane <allergic-to-(E-Mail Removed)> writes:

>On 2006-05-10, Allodoxaphobia <bit-(E-Mail Removed)> wrote:
>> On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
>>> Life used to be simple. I used to assign a static id in the 192.168.1.x
>>> range to every box on my home LAN and I used two static id's for my
>>> domain name server from my ISP, Comcast.
>>>
>>> Then I got a message from Comcast, warning that I needed to change my
>>> network settings to use DHCP and automatically get the dns
>>> from the provider. That's when things started going haywire.
>>
>> Which I ignored -- and nothing untoward happened here.
>> I let them assign whatever IP addy they want to the cable modem.
>> I use a set of DNS IP's that are _not_ Comcast's -- both before and
>> after their 'dramatic' changes.
>> I run a LAN with 2 linux boxen, 2 OS/2 boxen, and my First Wife's
>> WinXP box -- using fixed LAN IP assignments.
>> Like I said, I received their dire warning -- ignored it -- and nothing
>> untoward happened here.

>They weren't actually requiring that users use DHCP for their internal
>home networks, were they? I find that hard to believe, but if so,
>that reeks of ignorance/incompetence on Comcast's part.

Of course not. There have absolutely no way of telling if they did or did
not.
What I suspect happened was that they originally assigned fixed IP
addresses, and now decided that they wanted to go to dhcp so they could
handle more computers.

However, if the address they assign is a private non-routable address, then
doing double NAT might cause problems. Ie, your internal network does NAT
to put the local machines out onto the net, and then they do NAT on those
packets. Ie, the local machine assigns port translation into the high
thousands leaving the next nat layer a hard time figuring out how to do
port assignments.




>--


>*** Posted via a free Usenet account from http://www.teranews.com ***

Robert Harris wrote:

> Hamad bin Turki Salami wrote:
>> Life used to be simple. I used to assign a static id in the 192.168.1.x
>> range to every box on my home LAN and I used two static id's for my
>> domain name server from my ISP, Comcast.
>>
>> Then I got a message from Comcast, warning that I needed to change my
>> network settings to use DHCP and automatically get the dns
>> from the provider. That's when things started going haywire.
>>
>> I have Linux boxes, Windows boxes, and Mac OS X boxes on my
>> home network. The Mac boxes were no problem at all. They kept
>> working like nothing changed. The Windows boxes are doing okay
>> as well, with some hiccups. The Linux boxes aren't faring well.
>> I'd appreciate any help in getting things back to normal.
>>
>> Here's my setup: I have a cable modem taking the feed from Comcast.
>> That hooks to a Linksys wireless G router. The Linksys router has
>> a DHCP server built in. Since the Comcast change, I've allowed
>> the Linksys to hand out IP addresses and I've set all my clients
>> to get their IP addresses from DHCP.
>>
>> The problem is, my Linux boxes can't find the other computers anymore.
>> I can't print at all (my printer is attached to a Windows box).
>> To use ssh, I need to log in to my Linksys router to find out
>> what IP addresses are leased. Then, while my Mac and Windows
>> boxes seem to be telling the DHCP server what their names are,
>> the Linux boxes aren't.
>>
>> So here's my question:
>> How do I set up a dns functionality for my local LAN, so all
>> the machines know where each other are, even after their DHCP
>> leases expire and are reassigned? Can I just run my own dns server
>> and forget using Comcast's?
>>
>> I'd rather run it on Windows or Mac, since I'm probably going to
>> phase out Linux in the near future. But running it on Linux in
>> the near term is possible.
>>
>>
>>
> You are confusing two DHCP servers.
>
> 1. Your ISP uses DHCP to give the ISP interface of your router an IP
> address.
>
> 2. Your router uses DHCP to give your local machines IP addresses.
>
> You didn't have to use DHCP on your local net just because your ISP
> didn't give you a fixed IP address. But if you do,

Let me explain a little more what I think is going on. Maybe I'm
confused.

My router has always been using DHCP to get *its* IP address from
Comcast. That IP address is what anyone outside my LAN sees when any of
my machines communicates with them (because the router uses NAT). My
router has also been getting dns server addresses from Comcast. Until
now, those dns addresses have never changed, so I've just entered them
directly one each machine.

Recently, Comcast has moved the dns servers from the old addresses.
I don't know why. I don't know how often they'll change them in the
future.

The reason I'm using DHCP in my local LAN is that that way, the router
tells them the dns server addresses. Now, each individual machine could
use DHCP directly with Comcast to get the dns address, but I think
that's a bad idea. First, Comcast's official line is that it only
supports a single machine. If you have a LAN, you're supposed to use
some service from Comcast to set it up, and it probably only supports
Windows or some such bullshit, so I'm not going to do that. Also, I
don't want the outside world to see into my LAN. I like being behind
a firewall with one IP address.

Now, getting the dns address and getting the IP address for the local
LAN are logically distinct operations. However, I have 4 or 5 operating
systems on my LAN, and I don't want to take the time to figure out how
to do complicated stuff on all of them. On Mac OS X, it's easy; you can
do it with the gui. You open the Networking preference panel and it
gives you the option of setting a static IP address *and* getting your
dns from DHCP. If it were that easy on Linux and Windows, I probably
wouldn't be here, but none of my Linux or Windows based systems have
that option through the gui. That means digging a little deeper, which
is complicated and time consuming to do for multiple systems. I am
willing to do the work once, on one system, to set up a dns server. I
assume after I do that, it would be simple to direct any of my machines
to it and be done with my problems.


> A. Your router, which hands out your local IP addresses, presumably has
> DNS functionality as well. So your local machines use the router as
> their DNS server. Don't worry about it: the DHCP protocol will tell them
> where their DNS server is.

Unfortunately, I don't see how to make my router serve as a local dns
server. Maybe it can, maybe it can't. If someone here is familiar with
the Linksys wireless G router and knows how to do it, I'd be grateful.

> B. You can only see local machines that have active DHCP leases (if they
> do not have fixed addresses). Your linux machines probably don't declare
> their hostnames to DHCP by default so edit the file:
>
> /etc/dhcp3/dhclient
>
> (or something like it) suct that there is a line that says:
>
> send host name myhost
>
> (if the host name is myhost).
>
> I hope that this helps.
>
> Robert

Allodoxaphobia wrote:

> On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
>> Life used to be simple. I used to assign a static id in the 192.168.1.x
>> range to every box on my home LAN and I used two static id's for my
>> domain name server from my ISP, Comcast.
>>
>> Then I got a message from Comcast, warning that I needed to change my
>> network settings to use DHCP and automatically get the dns
>> from the provider. That's when things started going haywire.
>
> Which I ignored -- and nothing untoward happened here.
> I let them assign whatever IP addy they want to the cable modem.
> I use a set of DNS IP's that are _not_ Comcast's -- both before and
> after their 'dramatic' changes.
> I run a LAN with 2 linux boxen, 2 OS/2 boxen, and my First Wife's
> WinXP box -- using fixed LAN IP assignments.
> Like I said, I received their dire warning -- ignored it -- and nothing
> untoward happened here.

<offtopic>
Still running OS/2, huh? I used to run OS/2 until work commitments
forced me to start running Linux. At the time, Linux and OS/2 didn't
play well together on my PC and I had to drop OS/2. Has OS/2 changed
much in the past 5 years?
</offtopic>

I ignored Comcast's warning too. My router was already getting its
address by DHCP, and I thought there would be no sense to their chaning
the address of their dns server. Then one day I woke up and none of
my machines could find Yahoo or Google or Ebay ... So I started
switching over. I guess I could have just found another dns server,
like you have. But there should be an advantage to running a dns server
on my home LAN anyway, in terms of speed, right?

On 2006-05-10, Unruh <unruh-(E-Mail Removed)> wrote:
> Jim Cochrane <allergic-to-(E-Mail Removed)> writes:
>
>>On 2006-05-10, Allodoxaphobia <bit-(E-Mail Removed)> wrote:
>>> On Wed, 10 May 2006 10:43:15 -0600, Hamad bin Turki Salami wrote:
>>>> Life used to be simple. I used to assign a static id in the 192.168.1.x
>>>> range to every box on my home LAN and I used two static id's for my
>>>> domain name server from my ISP, Comcast.
>>>>
>>>> Then I got a message from Comcast, warning that I needed to change my
>>>> network settings to use DHCP and automatically get the dns
>>>> from the provider. That's when things started going haywire.
>>>
>>> Which I ignored -- and nothing untoward happened here.
>>> I let them assign whatever IP addy they want to the cable modem.
>>> I use a set of DNS IP's that are _not_ Comcast's -- both before and
>>> after their 'dramatic' changes.
>>> I run a LAN with 2 linux boxen, 2 OS/2 boxen, and my First Wife's
>>> WinXP box -- using fixed LAN IP assignments.
>>> Like I said, I received their dire warning -- ignored it -- and nothing
>>> untoward happened here.
>
>>They weren't actually requiring that users use DHCP for their internal
>>home networks, were they? I find that hard to believe, but if so,
>>that reeks of ignorance/incompetence on Comcast's part.
>
> Of course not. There have absolutely no way of telling if they did or did
> not.
> What I suspect happened was that they originally assigned fixed IP
> addresses, and now decided that they wanted to go to dhcp so they could
> handle more computers.

Ah, I misunderstood; thanks for clearing that up.

> However, if the address they assign is a private non-routable address, then

I guess you mean, for example, a 10.*.*.* address rather than a valid
internet address (right?). Do many broadband providers do that - assign
a private address instead of a valid public address?

> doing double NAT might cause problems. Ie, your internal network does NAT
> to put the local machines out onto the net, and then they do NAT on those
> packets. Ie, the local machine assigns port translation into the high
> thousands leaving the next nat layer a hard time figuring out how to do
> port assignments.


--


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