SIPCALC

By Manny Fernandez

November 21, 2018

Anyone that has read my blog, knows I use sipcalc on my Mac. I used to use it on my Linux box when I ran it as my primary OS. When I moved to Mac, I used it with ‘ports’ but later started running ‘homebrew’. I use it daily. I am going to give you some examples of how I use it.

Finding where the IP sits from a subnet’s perspective

As you can see in the screenshot above, if you wanted to figure out where the IP sits inside of a specific subnet you could simply type ‘sipcalc %ip-address% a slash and the number of bits. In the example above, we are given the IP address of 10.1.1.17/29 but we are not sure if the IP we want to use is the ‘network’ or the ‘broadcast’ etc. Simply typing ‘sipcalc 10.1.1.17/29’ will give you:

* The Decimal and Hex version of the host address
* The Address and Mask (Non-CIDR)
* The Network bits.
* The Broadcast Address
* The Cisco wildcard address for the network.
* The usable range of IPs.

Subnetting a /24 to be used by smaller subnets

In this example, you are setting up some transient network to use between some routers and core or distribution switches. You do not want to use a full /24 per router since you have numerous routers (such as in a DMZ where you have third-party companies dropping routers into your DC). Here, the customer has told you to use 10.240.254.0/24 and he would like to have 6 usable addresses (3 for each HSRP instance).

Here you can see that we started with the /24 subnet we wanted to use, followed by a ‘-s’ (lowercase s as capital ’S’ is for v6) to show a split based on the ’29’. Essentially, it means:

What /29 subnets could I get if I used a 10.240.254.0/24?

As you can see from the output, 10.240.254.0/29 would be the first subnet while the 10.240.254.8/29 would be the next, followed by 10.240.254.16/29 and so forth.

Subnetting a /24 to be used by smaller subnets with details

Similar to the previous example, if you wanted to know the /29 subnets but also wanted to provide details about each of the subnets, you could use the ‘-u’.

In this example, we not only see the /29 seperated as the previous command, but using the ‘-u’ will give you the ‘split verbose’ version of the output. This could be useful to provide to the third-party group so they understand the subnet and where they live in it.

Showing the ‘CLASS’
If, for whatever reason, you require to know the class of the IP addesses or subnets, you can use the ‘-c’ switch and it will display it.

Noteworthy:
Sipcalc supports IPv6. Sipcalc can take input in three forms, an ip-address/netmask, an interface or via stdin using the special character -.

To install using home-brew ‘brew install sipcalc’

Hope this helps.

SIPCALC

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