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Netmask problem

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  • 10-07-2007 10:48pm
    #1
    nobodythere
    Closed Accounts Posts: 2,349 ✭✭✭


    Hello all,
    I'm trying to set up something for a friend's cctv so that he can view it over the internet.

    I can view it fine wirelessly using the local IP address. My packet sniffer tells me it's only using TCP 5000/5001 (5000 for connections, 5001 for data).

    I have these ports forwarded correctly on the router (I can telnet to 5000 and 5001 and get a connection).

    However, when I try to connect using the broadband IP (static) it connects but won't send any data.

    My working theory is that it's something to with the netmask on the CCTV yoke being set to 255.255.255.0 so that when it gets a very foreign IP address outside of the subnet it runs into problem.

    So I was going to set the netmask to 0.0.0.0. I was just wondering what the possible implications of doing this are, if it would have any adverse effects etc...

    Thanks in advance.

    Edit: I only ask because getting at the box is a pain in the hole and I only want to have to do it once! :)


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    #2
    axer
    Registered Users Posts: 5,517 ✭✭✭axer


    grasshopa wrote:
    Hello all,
    I'm trying to set up something for a friend's cctv so that he can view it over the internet.

    I can view it fine wirelessly using the local IP address. My packet sniffer tells me it's only using TCP 5000/5001 (5000 for connections, 5001 for data).

    I have these ports forwarded correctly on the router (I can telnet to 5000 and 5001 and get a connection).

    However, when I try to connect using the broadband IP (static) it connects but won't send any data.

    My working theory is that it's something to with the netmask on the CCTV yoke being set to 255.255.255.0 so that when it gets a very foreign IP address outside of the subnet it runs into problem.

    So I was going to set the netmask to 0.0.0.0. I was just wondering what the possible implications of doing this are, if it would have any adverse effects etc...

    Thanks in advance.

    Edit: I only ask because getting at the box is a pain in the hole and I only want to have to do it once! :)
    how are you trying to connect to the cctv yoke? i.e. what are you typing into your browser to bring it up? just "http://xxx.xxx.xxx.xxx/"?

    I don't think setting the mask to 0.0.0.0 is going to help as it will not be able to communicate over the network then.


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    #3
    Moriarty
    Registered Users Posts: 6,007 ✭✭✭Moriarty


    Moved to Nets/Comms.


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    #4
    nobodythere
    Closed Accounts Posts: 2,349 ✭✭✭nobodythere


    axer wrote:
    how are you trying to connect to the cctv yoke? i.e. what are you typing into your browser to bring it up? just "http://xxx.xxx.xxx.xxx/"?

    I don't think setting the mask to 0.0.0.0 is going to help as it will not be able to communicate over the network then.

    It's not a browser connection, software comes with the DVR. the IP is 192.168.1.2

    I'm stumped as to what to do.

    Is there any way to fool it into believing it's on the same subnet as an internet ip address...


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    #5
    telecomsman
    Closed Accounts Posts: 48 ✭telecomsman


    Hi GrassHopa

    Ok, lets just go through a few things on the setup.

    Your Web Cam Application (DVR) has an IP address of 192.168.1.2 with a Netmask of 255.255.255.0. On your Wireless router you should have a public IP address on one interface, to talk to the internet, and a private IP address on the other....in this case say 192.1681.1 Netmask 255.255.255.0. You should have a NAT in place, to forward all traffic coming in on the Internet side to the internal IP of your application.Once they are on the same subnet this should be fine.

    If you give us more details we can help further.


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    #6
    bushy...
    Closed Accounts Posts: 1,467 ✭✭✭bushy...


    Run a vpn/tunnell , it'd be more secure and i'm sure he could find other uses for the tunnell once its there ( lots of stuff if its a shop/business etc) and esp since you say ....

    grasshopa wrote:
    I only ask because getting at the box is a pain in the hole and I only want to have to do it once! :)


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    #7
    axer
    Registered Users Posts: 5,517 ✭✭✭axer


    grasshopa wrote:
    It's not a browser connection, software comes with the DVR. the IP is 192.168.1.2

    I'm stumped as to what to do.

    Is there any way to fool it into believing it's on the same subnet as an internet ip address...
    What type of router is the shop using? as some have built in firewalls that would block outside communication.

    Another thing you can do short of creating a VPN tunnel is to setup a default server or IP passthrough and give the cctv yoke the external ip address at least that would help you rule out things.


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    #8
    Cake Fiend
    Registered Users Posts: 5,335 ✭✭✭Cake Fiend


    grasshopa wrote:
    Is there any way to fool it into believing it's on the same subnet as an internet ip address...

    This is not what you want to do.

    A common mistake is not setting the gateway IP on appliances like this - the gateway IP is needed to forward packets destined for a host outside of the local subnet.

    Next step would be to make sure that this connection is getting through the router's firewall, if there is one, as pointed out above.

    If the DVR is designed not to respond to requests from other networks (unlikely, but check the configuration, documentation and website), depending on your router, you may be able to source-NAT the incoming connection to the router's internal IP (if it's a basic DSL router, it probably won't have this ability) to trick the DVR into thinking the inbound connection is coming from a local machine.


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    #9
    nobodythere
    Closed Accounts Posts: 2,349 ✭✭✭nobodythere


    telecomsman wrote:
    Hi GrassHopa

    Ok, lets just go through a few things on the setup.

    Your Web Cam Application (DVR) has an IP address of 192.168.1.2 with a Netmask of 255.255.255.0. On your Wireless router you should have a public IP address on one interface, to talk to the internet, and a private IP address on the other....in this case say 192.168.1.1 Netmask 255.255.255.0. You should have a NAT in place, to forward all traffic coming in on the Internet side to the internal IP of your application.Once they are on the same subnet this should be fine.

    If you give us more details we can help further.

    The DVR is the CCTV recording box, it has a LAN connection on it.

    The NAT is set up correctly.

    I can connect fine using the LAN IP address of the DVR. However, I can't connect if I use the IP address visible to the internet. I can telnet to the ports but don't receive any data from it.

    The firewall is turned off on the netopia router.
    A common mistake is not setting the gateway IP on appliances like this - the gateway IP is needed to forward packets destined for a host outside of the local subnet.

    Good point, completely overlooked that!
    Run a vpn/tunnell , it'd be more secure and i'm sure he could find other uses for the tunnell once its there ( lots of stuff if its a shop/business etc) and esp since you say ....

    Would I need to have a computer on the local network to do that or could I do it using just the router?

    OT but what sort of uses do you have in mind....

    I have tried both IP passthrough and NAT.


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