Splitting Comcast Internet to 2 routers

August 11, 2009 1:25 PM

Can I split internet from one cable modem to 2 routers or is there better approach for what I am trying to achieve?

I am trying to set up a Linksys WRT54GL wireless router for a friend, but there is a problem because he already has a ZyXel wireless router in place that is provided by his job. My first thought was to tell him hey you are all set, you have a wireless router already. The problem is anything that he believes anything that goes through that router is monitored by his job (he swears they monitor everything through the router, not through his PC), so he doesn't want his family to pickup wifi from it. The ZyXel router is also password secured and he does not have the password (company IT department saved it on to his computer). He has cable internet provided by Comcast which his job also pays for.

What I would like to do is set up a second router (the Linksys WRT54GL) for the family internet. What is the best way to do this? I would like try to do this without them having to pay Comcast for additional service, but from what I've read they might have to at least buy another IP.

Would I put in a switch and then plug the Linkys and ZyXel routers into that? Or could I daisy-chain the routers with the Linksys first and then the ZyXel? Or is there just some other approach altogether?

posted by fx3000 to Technology (15 answers total)

Clarification: is the Zyxel router currently plugged into the Comcast cable modem?
posted by box at 1:28 PM on August 11, 2009

(I suspect your friend is mistaken about the corporate-monitoring thing, but I don't know enough to say for sure.)
posted by box at 1:29 PM on August 11, 2009

Would I put in a switch and then plug the Linkys and ZyXel routers into that?

You would need to pay comcast for a 2nd IP address, not sure if thats something that can be done ala carte or if he needs to move up to business class cable modem. Comcast may also need the mac address of the linksys too if it needs to be whitelisted.

FWIW, I think your friend is being paranoid.

Or could I daisy-chain the routers with the Linksys first and then the ZyXel?

You dont want to do this. Considering you cant change the gateway or IP on the zyxel, its a no go. I guess it might be doable if the zyxel is set to dhcp and if the linksys supports DMZ port.
posted by damn dirty ape at 1:39 PM on August 11, 2009

The ZyXel router is plugged into the Comcast cable modem and because my friend believes the monitoring happens through ZyXel router, I have to leave that in place. He works remotely, has no relations with the company IT department, is not technically savvy at all and is afraid he will get in big trouble with his job if the ZyXel router is altered. If he had some friends in IT and could talk the talk even a little, I would have him find out more about his options.
posted by fx3000 at 1:40 PM on August 11, 2009

the cable company modem is likely locked down to a single IP address, so a switch is unlikely to work. You'll probably need to go Cable Modem -> Linksys (192.168.1.0 network) -> Zyxel (192.168.2.0 network). If he doesn't have administrative control over the zyxel, he probably can't change the IP. If that's the case, then change the linksys network to something else that doesn't conflict with the network that the zyxel is using (192.168.X.0).
posted by jenkinsEar at 1:41 PM on August 11, 2009

Yes, but if the router is sniffing him, sending the traffic through the linksys into the zytel is the same as just plugging a computer into the zyxtel.
posted by damn dirty ape at 1:49 PM on August 11, 2009

I'm fairly sure your friend is over-paranoid, but paranoia when it comes to employers is a good thing.

Safest would be to get a separate internet connection. Perhaps Comcast will give a discount because there is already a connection at the house, even though it is billed to the company. Having the whole family use the company-supplied internet connection isn't wrong, but with this level of paranoia, it might be best not to.
posted by mad bomber what bombs at midnight at 1:50 PM on August 11, 2009

To clarify, the friends and family should plug into the linksys, the zyxel should be used exclusively for the work machine. Since the linksys acts as a switch, unless the zyxel is sniffing the outside network (unlikely), it's fairly safe.
posted by jenkinsEar at 1:52 PM on August 11, 2009

I'd tell your friend to be a bit more courageous about this. You should simply take the Zyxel router out of the picture entirely and setup the Linksys in its place. Make sure you employ encryption and consider disabling SSID broadcast and using MAC ID filters.

I work remotely like your friend and there is no way that I would allow my employer to enforce a strict policy on my household's access to the internet unless they had outlined a policy forbidding usage of that broadband line for anything other than work. In that case, your friend will need to talk to Comcast about setting up an additional IP address.
posted by Dave. at 1:58 PM on August 11, 2009

Much will depend on whether the Comcast connection his company pays for is a business class service. If it is, you may have no choice but to leave the Zyxel device hooked directly to the cable modem (the IP allocation may be provisioned based on the MAC address of the Zyxel). In that case, you could plug another router into the Zyxel, but all that traffic would also be monitored (which, I agree, they're probably not doing on the router itself), so that wouldn't really help. You would probably need a second IP from Comcast or pay for an entirely separate residential connection.

If the Comcast connection is just a vanilla residential service for which his company happens to pay, you could hook the Linksys to the cable modem, and the Zyxel to the Linksys. Problem solved. (The only thing to watch out for is that the Linksys doesn't block and properly forwards any ports for his work services, like VPN.)
posted by paulg at 2:02 PM on August 11, 2009

1. Unplug ZyXel.
2. Plug in Linksys.
3. If employer complains, find new job or alternet connection such as MeFi.
4. See therapist re: paranoia.
posted by mikewas at 3:01 PM on August 11, 2009

You should be able to set it up as Modem>Linksys>Zyxel>Computer. Might need to do some MAC cloning to get the modem to accept, but it should be fairly easy.

Or just try what mikewas said.
posted by stewiethegreat at 3:14 PM on August 11, 2009

You can most likely grab the password to the Zyxel by using Eureka! which is part of System Information (under tools or something)
Just drag the crosshairs into the password field when it has the password automatically entered in and you can recover the password.

Make Linksys the real router, give the Zyxel a static IP on the internal network of the linksys and see if everything works.
posted by ijoyner at 6:29 PM on August 11, 2009

Alternate solution: Introduce him to Tor to ease his privacy concerns.
posted by jgunsch at 7:47 PM on August 11, 2009

Thanks for all the suggestions. My friend decided to add another line. He is too paranoid, but then again ones job is extra valuable nowadays and if there even a shred of doubt I almost don't blame him. I would have liked to tried this just for the fun of it, but then again I would not want to be responsible for getting him in how water.
posted by fx3000 at 7:25 PM on August 13, 2009