Static IP not working - only DHCP does

JLamyJLamy UK
edited August 2004 in Science & Tech
HI peeps.
Is there any benefit, such as security, to switching to static IP from DHCP IP, as I have done this on my Samsung X10 laptop, but on the desktop computer it doesnt like static IP at all. I get good wireless signal strength and the desktop works WITH DHCP, but if I set a static IP of my choice then no internet conection at all. I get packets sent, but always zero packets received. Is there a known fix for this? Shall I just leave DHCP enabled for the desktop and leave the laptop as static? Shall I limit the maximum number of DHCP users to only the number of computers that actually use the network, as it is set at 100 at present?

Comments

  • kryystkryyst Ontario, Canada
    edited August 2004
    There are benefits to using Static of DHCP but not security benefits. If you want to increase the security then limit the number of DHCP users to the number of computers that will be using it. However that only stops the machine from assigning an address to an outside source. if they find your network they can still create their own static IP and hook up if they figure out what IP you are using.

    Though as to why your machine won't accept a static IP that's kind of strange. Are you perhaps putting in the wrong gateway or DNS?
  • JLamyJLamy UK
    edited August 2004
    kryyst wrote:
    There are benefits to using Static of DHCP but not security benefits. If you want to increase the security then limit the number of DHCP users to the number of computers that will be using it. However that only stops the machine from assigning an address to an outside source. if they find your network they can still create their own static IP and hook up if they figure out what IP you are using.

    Though as to why your machine won't accept a static IP that's kind of strange. Are you perhaps putting in the wrong gateway or DNS?


    OK so no security benefits. Port forwarding befits? Can I open a port range to the whole of my local network, not just 1 specific IP address? Is it possible to stop intruders getting in my network by limiting IP addresses in general (as in only DHCP, and no other static IP's allolwed)? At present I have set WEP 128bit (highest protection my hardware can support), SSID disabled which is set to fairly random name and MAC address filtering limited to only my wireless machines.

    In my network settings:
    Manually configured
    IP address: 192.168.1.25
    Subnet mask: 255.255.255.0
    Default gateway: 192.168.1.1 (router IP)
    Preferred DNS server: 192.168.1.1 (router IP)

    My router is LinkSys WRT54G with firmware v2.02.7
  • kryystkryyst Ontario, Canada
    edited August 2004
    Ok first just set your DNS to autodetect and then you'd be able to use static IP. Because your router isn't a dns you can't use it as the preferred DNS. You'd have to put in the DNS servers for your ISP.

    Next because you only have 2 machines on your network even though you are using DHCP their IP address's will in all likelyness never change as when the DHCP lease is up that machine will try and optain the same IP it had before and unless there is a fluke it should be able to get it.

    As far as I know you can't open up incoming ports to more then one local machine as there would be a conflict in that the incoming port wouldn't know which machine to go to for the information. You can block IP ranges but you can't specifically state DHCP or Static. That would just be how the range is so if you state anything .100 and up is DHCP and you block anything from .1 to .99 then that is the same thing.

    As far as security goes though if you have WEP128 and you aren't broadcasting your SSID that alone is enough to stop almost anyone but the most dedicated. MAC filltering on top of that will stop the other extremely determined. Beyond that you can't do much as you can spoof a MAC address and someone with enough skills and the right software could potentially get in. But the risk is realistically non-existant.
  • JLamyJLamy UK
    edited August 2004
    Thanks Kryyst. I have given up and have just left DHCP enabled on the desktop. And as you say, have setup maximum available security options.
  • kryystkryyst Ontario, Canada
    edited August 2004
    No problem. Stupid question perhaps on the static IP thingy you don't by chance have more then one machine with the same Ip or possibly going outside of your IP range? Just on a whim if you want to play with it more look at the ip information you are getting from your DHCP connection (from dos do ipconfig /all). Then assign that IP statically to your machine and see if it works.
  • JLamyJLamy UK
    edited August 2004
    No, I only have 2 machines connected to router. On the lappy it has static of 192.168.1.11 - and it worked 1st time. On the desktop it has DHCP assignment of 192.168.1.101. Even if I change from dynamic to static from within Windows, I lose all internet connectivity the moment I click OK to confirm changes. MSN messenger signing out etc and not being able to get back in or load up any web pages. I get the above info from the ipconfig /all command too.
  • kryystkryyst Ontario, Canada
    edited August 2004
    So even if you swtich to static and plug in ip 192.168.1.101, subnet 255.255.255.0 and gateway 192.168.1.1 (I'm guessing that's your router) and leave the DNS as autodetect it doesn't work? Very strange, but it's not the first time I've scene it happen. If DHCP is working don't frett it.
  • JLamyJLamy UK
    edited August 2004
    Correct - But then again would that work as that IP belongs to DHCP IP range, so one would expect router to reject manual IP of that? I have tried this and nothing refused, just no internet connection!
  • kryystkryyst Ontario, Canada
    edited August 2004
    No the DHCP protocol won't reject a static IP in the DHCP range. It'll only potentially cause a conflict of it tries to assign that IP to another machine. Which in your case will probably never happen.
  • JLamyJLamy UK
    edited August 2004
    Oh right - Didn't know this! I learnt something today! :)
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