Hey Guys,
I'm a new Mepis user, and I have an interesting situation to relate.

I have Mepis 3.3.1 running on my IBM 300PL with a Linksys NIC.
My internet is ADSL (Verizon) which, from the modem/router, goes to a 3COM hub, and then splits to my XP box and also to my Mepis box.
My internet connection on my Mepis box works fine ONLY if i connect it DIRECTLY to the DSL router on startup, and THEN I can move the cable over the hub. However if I leave the Mepis NIC connected to the hub on startup, Internet will not work, yet the internet on the XP box works fine if I leave it connected to the hub.
Although this is just a little inconvenience, it still is inconvenient to have to unplug and replug cat5 cable in order to get my internet to work right.

What is causing this? What can I do to fix it? Any ideas?

thanks,
Stu

Is your verizon router a NAT device? If not, it may be that XP is snatching your only available IP address before linux boots. Also, swap cables between the XP box and the linux box. A out of spec cable can cause problems like that.

>>Is your verizon router a NAT device? If not, it may be that XP is snatching your only available IP address before linux boots. Also, swap cables between the XP box and the linux box. A out of spec cable can cause problems like that.<<

Jerre Cope,
Thanks for the response. I swapped net cables, with no change in situation, so I think we can rule that problem out.

What is NAT? and how can I find out whether my DSL modem/router is or not? I think you're on to something because the MEPIS box seems to work better if I allow it to connect first, and then the XP box... who knows.
thanks,
Stu

---Did some research: I have a Westell 2200 router, it IS NAT..

Now I'd compare /var/log/messages and watch the dhcp conversation during a successful connect vs what happens when you connect through the hub.

Also, I expect you can login to your westell box by pointing your browser to it's private IP address (maybe 192.168.1.1) This may afford a look at the dhcp log from the router side. You may be able to set the router to assign IP address by MAC address (use ifconfig -a to see you're MAC on linux). This way you can enforce consistant IP address assignment between the machines on your network.

Sorry to be pedantic, but I'm not sure that I understand your setup. You have a DSL modem connected by ethernet to a router, which is connected to a hub? Or are you calling the modem a router and the router a hub?

A hub is basically a "piece of wire" and shouldn't affect anything.

It may be that you have Windows set up with a static IP address, and that your router has no DHCP. Or maybe what you call a hup is not passing DHCP. Or it may be that your windows box has "connection sharing" enabled on one of its other network connections (dialup or wireless, perhaps?) and therefore is serving bogus IP addresses to your Linux box.

Open a command line in Windows and type "ipconfig." Open a command line in Linux (the working config and the not working configs) and type "ifconfig". The results should explain what's going on.

--------------------------------------------------------
GVC said...
Sorry to be pedantic, but I'm not sure that I understand your setup. You have a DSL modem connected by ethernet to a router, which is connected to a hub? Or are you calling the modem a router and the router a hub?

A hub is basically a "piece of wire" and shouldn't affect anything.

It may be that you have Windows set up with a static IP address, and that your router has no DHCP. Or maybe what you call a hup is not passing DHCP. Or it may be that your windows box has "connection sharing" enabled on one of its other network connections (dialup or wireless, perhaps?) and therefore is serving bogus IP addresses to your Linux box.

Open a command line in Windows and type "ipconfig." Open a command line in Linux (the working config and the not working configs) and type "ifconfig". The results should explain what's going on.
--------------------------------------------------------

gvc,
here's the deal, to eleviate some of the ambiguity. I have a DSL connection (DSL modem = router). so the phone line goes to the DSL modem, and the Network cable goes from the DSL modem to my hub...3COM box with 5 CAT5 connections, one set as upload (for the DSL ethernet connx).
OK, now I have 2 computers hooked up to the hub: one is my XP box (which has NO problems connecting to the Net), the other is my MEPIS box.
The problem therein lies with the connection to the MEPIS box. If I want to connect to the internet via ethernet, i have to connect the MEPIS computer DIRECTLY to the DSL modem, then run ADSL/PPPoE setup so that it sees the DSL modem (aka router) and once it is configured, ONLY THEN can I switch the ethernet cable for the MEPIS machine BACK to the hub (so that both computers can be on the net).
What's frustrating is that I have to go through this process EVERY TIME i want to connect to the internet. If I shut down the computer and restart for any reason, I have to do this all over again.
What I want to know is... is there some way I can configure this pig to automatically connect directly THROUGH the hub to the DSL modem? I want to run 2 systems simultaneously without having to jump through hoops to get there.
Any help you guys can provide would be very greatly appreciated. As always, LQ is the best!
Thanks,
Stu
PS: I checked ifconfig and ipconfig, and i couldn't find anything peculiar...I'd post the output but i don't need to publish my IP's to the world

I'm still confused as to what the 3com box really is. If it is a DSL router, it should be able to negotiate the ppoe with your DSL provider, and then provide DHCP to your downstream computers (windows and linux).

When you say that your windows box works fine, are you using ppoe software provided by your isp, or are you just using "obtain address automatically" in the network configuration? If the latter, the same thing should work with linux.

If the former, your isp probably allows only one ip address to be obtained.

I understand the wish for privacy, but I think the ifconfig/ipconfig output would be really illuminating. If you have ip addresses starting with 192.168, they are local (served up by the router). Other IP addresses are probably dished up by ppoe. You can just change the first two octets to xxx.yyy.

Ahh. I think I see your problem. If you have to go through ppoe to connect, then your dsl modem is NOT a router and so your one and only IP address is caught up with whoever gets there first. I would say you have two options:

Make your Memphis box the router (you need two interfaces cards for this), or buy a linksys type router and change both machines to operate dhcp

-------------------------------------
gvc said...
I'm still confused as to what the 3com box really is. If it is a DSL router, it should be able to negotiate the ppoe with your DSL provider, and then provide DHCP to your downstream computers (windows and linux).
-------------------------------------
spage0506 says...
I still don't think you've got a clear picture of the situation over here. I have a DSL modem AND a hub... 2 separate aparatus here. the internet connection is furnished by the DSL modem, which is in turn wired to my hub (via CAT5 cable) and split off to two separate computers.

here's a diagram... 1= dsl modem... 2= hub... 3=XP machine,.. and 4 = Mepis machine

[2]--------[1]
/ \
/ \
3 4

---------------------------------------
gvc said...
When you say that your windows box works fine, are you using ppoe software provided by your isp, or are you just using "obtain address automatically" in the network configuration? If the latter, the same thing should work with linux.
---------------------------------------
spage0506 says...
My network configuration is "obtain address automatically", and i know both computers are getting IP addresses... they are not local address, but ones furnished by my ISP.

bingo.

Truly your modem is a modem and you haven't a router at all. Generally your ISP makes you pay for more than one address which is why most people use a router with NAT to translate their one Public IP address to 254 private ones. PPOE isn't really a protocal three machines can share on the same wire.

Refer to my previous post and add a router to your network.

Jerre Cope,
Thanks for the reply. That seems to make a lot of sense. Just one question... where can I get the info on how to I set my Linux machine to be a router for my network?
thanks..

I'm not familiar with MEPIS, so I'll give you the general strategy and a link or so. You need two NIC's for a miniumum. One, perhaps eth0 will connect directly to the modem. The other interface (eth1) will connect to your hub,

eth0 will use ipchains (invoking the firewall utility built into the kernel) to provide NAT routing to eth1.

eth1 should use dhcp to provide address, dns, and gateway information to the other computers connected to the hub. Try dnsmasq or BIND for the dns. If you use BIND, I perfer to use Webmin for configuration.

My favorite way to setup a firewall is with Shorewall. There is also alot of very good networking documentation and diagrams on the project's home page

http://sourceforge.net/projects/shorewall/

Lastly, use the LQ Forum on networking to lookup what the experts say about building a router.

Here are 3 alternatives from easiest to hardest (only the 3rd of which directly addresses your question).

1. Buy a Cable/DSL router. These can be had for less than $50. While you're at it, buy a wireless router for $20 more and you're set for guests that have wireless laptops. The router will replace your hub (or you can use your hub downstream if you need to connect more than 4 ethernet devices to your network).

2. Buy an ethernet NIC and plug it into your Windows box. Connect the new NIC to your hub and the old one to your DSL modem. Go to "properties" for the old network connecting and check "share this connection with other computers on the network." That's all you have to do to make your Windows box a router. It will give the new NIC an IP address of 192.168.0.1 and a network of 192.168.0.*. It will also serve DHCP addresses in this range and route via NAT to your DSL connection.

3. Put the extra NIC in your Linux box. This requires configuration of several components:

- 1. pick a static IP address/network for your new NIC. Probably 192.168.something.*

- 2. set up a DHCP server so that new devices plugged in to your network get automatic IPs on your new local net. For this you need to install and configure dhcpd.

- 3. set up NAT (address translation) so that machines on your local net can see the internet. This I've never done but as the article above notes, it is done with iptables.