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dont know if this is possible...?

Discussion in 'Networks' started by shaggy, Jan 2, 2008.

  1. shaggy

    shaggy Byte Poster

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    Happy new year everyone!

    Ok down to business, i have a desktop with a cable internet connection via a motorola surfboard modem

    I came across a sky/netgear wireless router, model DG834GT which a friend used for his ADSL connection. I have unlocked the router and flashed it back to netgear firmware.

    what i would like to do is essentially use it in conjunction with my motorola surfboard to give both my desktop and laptop individual internet connections, at current i have to use a switch and ICS which means having the desktop turned on to give the laptop access.

    I dont know if this is even possible with this model router? been fiddling about with connections but cant work it out, never done a setup like this one before, from my cable modem i only have a usb port and a standard ethernet port

    any words of wisdom appreciated, cheers
     
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  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Practicaly all ADSL routers cannot be used in this way. Basicaly - you need access to the point between the modem and the router parts, and that point is not available to the outside!

    You can get new cable routers for about £20 these days, so not very expensive!

    Harry.
     
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  3. shaggy

    shaggy Byte Poster

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    Ah bugger, thought the router parts would have been seperate inside.

    never mind, will make a nice paperweight

    thanks
     
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  4. zebulebu

    zebulebu Terabyte Poster

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    Yeps. Linksys WRT54G (I do so much promotion of this damn blue box that someone will accuse me of shilling for Linksys soon!)

    You can pick them up for about thirty quid on FleaBay, then flash them with decent firmware like DD-WRT or Open-WRT to give you features you'd need to pay about 500 quid for elsewhere. You can also get other makes/models that are third-party flashable.
     
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  5. Fergal1982

    Fergal1982 Petabyte Poster

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    surely if the modem has an ethernet connection, you could just plug the modem into the netgear router, and assign it an IP. Then you just need to set the default gateway on the pc's to point to the IP for the modem.

    you would need to switch off the DHCP on either the modem, or the router in order to to this though.

    Its maybe not the perfect setup, but hell, you already have the components.
     
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  6. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    You only get one IP address from the cable company. Using the router in the way you suggest is just like using it as a switch - because that is where you are plugging into. So when you plug another device in it won't work because either it won't get an IP addy at all, or it will duplicate the other PC's address.

    Harry.
     
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  7. Fergal1982

    Fergal1982 Petabyte Poster

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    ummm. not really. surely the modem has an internal DHCP and addressing system, no? Im basing this off my ADSL router knowledge admittedly, but surely the Cable modem receives an external IP from the cable company, and assigns the attached pc (via ethernet or usb) an IP for internal use, just like an ADSL router.

    Therefore, if you attach the cable modem to the router via the ethernet port, and disable the DHCP on the modem itself, you can then assign it a static IP from the router. That way, the DHCP from the router is handling all the internal DHCP usage, so all the devices on the network are assigned unique internal addresses. The external IP is handled in that situation by the modem.

    Alternatively, you could disable DHCP on the router, and have the modem handle it. The very fact that the modem has a ethernet connection suggests to me that it was designed in such a way, that you could attack a switch to the modem via that port, to have multiple connections.
     
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  8. Sparky
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    Sparky Zettabyte Poster Moderator

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    Don’t think this will work. You would need to patch the cable modem into the WAN port of the Netgear which you can’t do as it is a RJ11 port. The Netgear would have to NAT everything on the LAN which isnt possible as you cant physically patch anything into the WAN port in this case.
     
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  9. Fergal1982

    Fergal1982 Petabyte Poster

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    no, you wouldnt. You would patch the modem into one of the network ports on the router itself via the ethernet port on the modem. Then disable DHCP on one of the devices, either the modem or the router, and allow the dhcp on the other to take over the DHCP for the whole internal network.

    You would most likely need to hardcode each individual machine so that its default gateway was the IP assigned for the modem, rather than that of the router, since the router wouldnt have a network connection.

    Using this very method, I hooked up my BT Home Hub as a WAP to my netgear router, so I know that its sound in theory.

    This seems to corroborate my theory too.
     
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  10. Fergal1982

    Fergal1982 Petabyte Poster

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    Hell, to be honest, shaggy already has the necessary equipment to try and make it work. Should he not at least try it out? Why spend even so little as £20 on something when you could buy a few pints with it, and use what you have. And whilst you are doing it, you can learn some more about how the stuff is working, what settings are available on the device and what they do.

    And if it fails and doesnt work, as most people here seem to think, then sure, I was wrong, and you have to fork out money to get what you want. But at least you tried to save yourself the money. For the very fact you have the equipment to hand, what have you got to lose?
     
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  11. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Nearly correct. It actualy assigns the IP it gets from the cable co to the attached PC, and in effect becomes a bridge, with no IP address of its own.
    The snag is that you are attaching it to the switch which is 'after' the router. The router is expecting to route between the WAN and the switch, but you are not attaching anything to the WAN. So it won't route.
    The Ethernet connection is so you can attach a router - but you have to plug it in to the WAN port on the router. You get such a port on cable routers, but not normally on ADSL routers.

    Harry.
     
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  12. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    That works because the AP is effectively attached to the switch. No routing is involved beyond normal layer 2 switch action.

    Harry.
     
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  13. Sparky
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    Sparky Zettabyte Poster Moderator

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    The cable modem doesn’t have a LAN IP address though; it just passes through the one WAN IP address to the client PC. If you could patch this cable into the WAN port in the Netgear then it would work as the Netgear could be the NAT device and you can get multiple PCs (on the LAN) access to the internet.

    As the WAN port on the Netgear is a RJ11 then you cannot do this.

    Just to contradict what I have just said supposedly the cable modem supports 63 devices however the extra network component is listed as just being a switch. WTF!? :biggrin
     
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  14. Fergal1982

    Fergal1982 Petabyte Poster

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    Ah, ok I get you now. Then yeah, I suppose it wouldnt work.
     
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  15. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Depends on what docs you saw. The one I looked at said that it would "Support up to 63 computers (additional networking hardware required)". i.e. you need a router!

    Harry.
     
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  16. Sparky
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    Yup, you definitely need a router. This is the doc though...
     

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