Where do I learn about IP blocks and subnets? Or is there just a calculator that does it all for me?

Posted by cwd on Server Fault See other posts from Server Fault or by cwd
Published on 2011-11-22T00:56:24Z Indexed on 2011/11/22 1:54 UTC
Read the original article Hit count: 391

Filed under:

networking

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iptables

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ip

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subnet

Amazon's elastic compute tool (among others) requires the ip block format for their command:

ec2-authorize websrv -P tcp -p 80 -s 205.192.0.0/16

I may be doing this wrong, but as far as I can tell I need to use the block format even for a single IP address. 1) So, how would I do that for this IP?

71.75.232.132

Several years ago I took a CCNA class, and I remember going over IPs and subnets, masks, broadcast addresses, class a/b/c networks, etc. However a lot seems to have changed since then - for example I don't think you can tell what "class" a network is in just by looking at it anymore - sometimes they could be multiple classes.

2) Anyhow, my second question is where do I go to get a refresher on all these things?

3) Or should I just be using ipcalc or an online calculator to do it all for me - and if so, which one?

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