Connecting an extra computer to Internet

[Rick Stevens]

On Thu, 2007-07-05 at 22:22 +0100, Paul Smith wrote:
> On 7/5/07, Rick Stevens <rstevens at internap.com> wrote:
> > > > > I have a cable-based (not optic) modem/router to connect to the
> > > > > Internet (ADSL), which works fine. However, a friend comes in from
> > > > > time to time, bringing her laptop. Is there some cheap and easy way of
> > > > > letting her laptop to connect to Internet? Unfortunately, I cannot see
> > > > > any place in the modem/router to connect an extra cable...
> > > >
> > > > Do you have a router installed, or are you connecting your computer
> > > > directly to the DSL modem? The two are usually separate devices, with
> > > > the router sitting between the modem and the computer. Routers
> > > > generally have at least 4 network jacks. The one I use at home is a
> > > > wireless router as well, which is much more convenient for laptops.
> > >
> > > Thanks, Sultan Saini. I am connecting my computer directly to the DLS
> > > modem (provided by my ISP). I think my DLS model is also a router, as
> > > its configuration is done through a web interface.
> >
> > Your modem contains a router.  ADSL needs that.  The question is,
> > how does your computer plug into the modem?  If it uses an RJ45
> > connector (a cable that looks like the cord you use to plug your phone
> > into the wall--but with 8 pins rather than 4), then the easiest way to
> > do it is:
> >
> >     ADSL line <--> existing modem <--> switch <--> computer
> >                                               <--> 2nd computer
> >                                               <--> 3rd computer
> >
> > The "switch" is an item you can buy for $20 US at most stores.  Many
> > companies actually make an ADSL modem/router/switch/WAN access point
> > combo box.
> >
> > For example, D-Link's DSL-2640B is an ADSL modem, router/firewall,
> > 4-port gigabit switch and 802.11g wireless access point.  The URL is
> > http://www.dlink.com/products/?sec=1&pid=567.  Other companies (Airlink,
> > Cisco, etc.) make similar beasties.
> >
> > One of these should be enough for you to do full-up networking at home.
> > If you're unfamiliar with wireless networking, make sure you set the
> > ESSID and WEP key or WPA passphrases to something other than the default
> > so other wireless users can't hijack your bandwidth.  I even go so far
> > as to not have the wireless stuff broadcast the ESSID.  If you don't
> > know my ESSID, you can't find it.  Just because I'm paranoid doesn't
> > mean they aren't out to get me!
> 
> Thanks, Rick and all other respondents. Yes, my DSL modem connects to
> my computer by using an RJ45 connector. The shopkeeper where I went to
> buy a switch claims that the switch may not work and that I should
> instead buy a router. So, I would like to ask you whether it is really
> as he claims.

It is possible.  It depends on whether your modem can accept multiple
connections.  In other words, some modems are simply point-to-point and
some have a router built in.  If you have a point-to-point modem, no
adding a switch won't work.  That's why I recommended the D-Link unit.
It has everything you could want in a single box (modem, router,
firewall, switch, DHCP server and wireless access point).

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- Rick Stevens, Principal Engineer             rstevens at internap.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
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-  Time: Nature's way of keeping everything from happening at once.  -
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