Accept all requests from 10. IP?

NotionCommotion · 04-09-2017, 12:30 AM

I thought I was suppose to use a zero for the last three ranges, but it appears that doing so does not all any IP such as 10.123.123.123 or 10.1.1.1 to get through. How should I be doing this? Thanks

Code:

14   ACCEPT     tcp  --  10.0.0.0/24          0.0.0.0/0           tcp dpt:445 state NEW

smallpond · 04-09-2017, 09:51 AM

Your netmask should be just the first 8 bits, not the first 24:

Code:

14   ACCEPT     tcp  --  10.0.0.0/8           0.0.0.0/0           tcp dpt:445 state NEW

NotionCommotion · 04-09-2017, 11:17 AM

Quote:

Originally Posted by smallpond

Your netmask should be just the first 8 bits, not the first 24:

Ah, I think I finally starting to get this IP thing. Let me explain my current understanding, and please correct me where I am wrong.

All IPv4 require 32 bits, and a given network can have?

(1) class A network with 2^24 IPs (16,777,216) where the remaining 8 bits are used to specify it is a class A network?
(16) class B networks with 2^20 IPs (1,048,576) where 8 of the remaining 12 bits are used to specify it is a class B network and the remaining 4 bits are used to specify which of the 16 (172.16 to 172.31) it is?
(256) class C networks with 2^16 IPs (65,536) where 8 of the remaining 16 bits are used to specify it is a class C network and the remaining 8 bits are used to specify which of the 256 (198.168 to ???) it is?

So, then these remaining 8, 12, or 16 bits are used to mask the IP so they don't conflict with others?

Yea, I am sure I am wrong multiple times!

Thanks in advance.

chrism01 · 04-09-2017, 07:38 PM

This may help https://en.wikipedia.org/wiki/Subnetwork and this IP Calc to play with http://www.jodies.de/ipcalc - very informative.

The /8 (aka Class A) means use the FIRST 8 bits as the network address and the remaining 24 bits as host addresses etc

NotionCommotion · 04-09-2017, 08:18 PM

Thanks chrism01, I think playing with the calculator will help it sink in.

r3sistance · 04-10-2017, 06:00 AM

To be fair, Class A, Class B and Class C subnetworking isn't really used anymore, rather everything went to CIDR notation where Class A is equiv of a /8, Class B a /16 and Class C a /24 where the notation indicates the number of bits within the network address. CIDR is generally all round better, tho I am guessing Colleges and Universities probably still the old class style of subnetworking... cas those places usually get stuck in the past.