Subnet mask problem 1

[litton1]

Hello all, I have been having a network problem for a while now so I decided to put the problem on the Linux server forum, see thread54-1085825 . Anyway the result was that I seem have a subnet mask problem. Not sure what that is and I certainly don’t know how to fix this. I would be very thankful if someone could help me resolve this issue. The problem I guess must be in the Ipcop router setup but it maybe in the ISDN modem router. If any further information is needed please let me know. The last three posts on the aforementioned thread hold quite a bit of information

Binary Intelligence, true or false?

 

[Koonan]

It does look like it might be subnet mask issue. It looks like your client IP address 192.168.2.4. What is your subnet mask set to? It should look like 255.255.255.0, but you might have it set to 255.0.0.0.

Mike


=====================================
The good ole days weren't always good
and tomorrow ain't as bad as it seems
=====================================

 

[Serbtastic]

You need to set the subnet mask on your internal interface (eth0) to 255.255.255.0. Currently it is 255.0.0.0, which is why it thinks httpd.apache.org (192.87.106.226) is local to your network, and why it can't get to it.

You should be able to go into the IPCOP gui admin screen, and change it there. Also, if your clients are obtaining their IP via DHCP, you'll need to change it on the DHCP page as well.

 

[Koonan]

Here's a nice site about IP addressing and IP Subnetting.

http://www.learntcpip.com/

Mike

=====================================
The good ole days weren't always good
and tomorrow ain't as bad as it seems
=====================================

 

[litton1]

Thanks serbtastic and koonan that is really really helpful. I will try to change it and also I will look at the suggested link and see if I can learn something. I will let you all know the result. Thanks again very much appreciated

Binary Intelligence, true or false?

 

[litton1]

Well who would have thought it, subnet masks are in theory quite simple and the site has some good vids

http://www.learntcpip.com/.

But before I make any changes could you please just verify that they are correct. First I will just reiterate the path out of my network to the Internet.

From a client machine eg 192.168.2.4 on to the IPCOP router with 2 Ethernet cards the first is 192.168.2.1 then onto the second, which is 10.0.0.5, then to the ISDN modem which is 10.0.0.1 and then out to the Internet. So would I be correct in using these subnet masks IP:192.168.2.4 SM:255.255.255.0--à go to the IPCOP IP:192.168.2.1 SM: 255.255.255.255 (as it is all a host address) then to the second Ethernet card IP:10.0.0.5 SM:255.255.255.0 then to the ISDN router IP 10.0.0.1 SM: 255.255.255.255

Or does my whole addressing system need to be changed. Hope that is clear enough to understand. Thanks in advance


Binary Intelligence, true or false?

 

[Koonan]

255.255.255.255 is a special subnet mask, used for broadcasts, it should never be used as a subnet mask for a client. As an educated guess, yes the 192.168.2.0 network ID should have a 255.255.255.0 subnet mask. The 10.0.0.0 network ID on the other hand should be 255.0.0.0. It's a common practice to break a 10.0.0.0 network into smaller subnets (using different subnet masks). I going to guess that you haven't done this.

Mike


=====================================
The good ole days weren't always good
and tomorrow ain't as bad as it seems
=====================================

 

[litton1]

No I did not do this. I just fumbled blindly thinking yeh whatever shove something in and if it works all is well. This has now come back to bite me in the …

What is I could do is try to change the address of the ISDN modem so that it is 192.168.1.1
And then alter the 10.0.0.5 to 192.168.1.2 so they reside in the same IP range. If I did this would their subnet mask be 255.0.0.0 as you have just suggested for the 10.0.0.1
this seems more logic. What do you think?


Binary Intelligence, true or false?

 

[Koonan]

The 192.168.1.0 network needs a subnet mask of 255.255.255.0. If you use a 255.0.0.0 with that network ID you are doing something called Supernetting, which is what's causing your problem.



=====================================
The good ole days weren't always good
and tomorrow ain't as bad as it seems
=====================================

 

[litton1]

Yes I see, it is the top of my network hierarchy and so holds the highest net mask.

Excellent thanks I am going to go and give this a try and will let you know the outcome ^_^

Binary Intelligence, true or false?

 

[litton1]

Thanks the problem is finally sorted. Rearranged all the subnet masks and IPs

Binary Intelligence, true or false?