While setting up some iptables rules the other day to allow connections from a clients IP range to are servers in London. I needed to translate an IP range expressed as a CIDR to real from and to values. I remembered being taught how to do so in college but that was a long time ago now so was looking for an online tool, I couldn’t find any I liked so I checked for a Linux tool. I found one called sipcalc which is really good. Not only can it do what I needed with translating the CIDR notation it can do a few other calculations / conversions as well.
Simple install process under Ubuntu just the usual
sudo apt-get install sipcalc
Once install its ready to go. To convert an IP range expressed in CIDR format you simply do
sipcalc 165.19.104.1/23
-[ipv4 : 165.19.104.1/23] - 0 [CIDR] Host address - 165.19.104.1 Host address (decimal) - 2769512449 Host address (hex) - A5136801 Network address - 165.19.104.0 Network mask - 255.255.254.0 Network mask (bits) - 23 Network mask (hex) - FFFFFE00 Broadcast address - 165.19.105.255 Cisco wildcard - 0.0.1.255 Addresses in network - 512 Network range - 165.19.104.0 - 165.19.105.255 Usable range - 165.19.104.1 - 165.19.105.254
This is what I needed to do and it worked just fine giving me the network range and more.
Another useful one is to pass in an IP address and subnet mask this once again is a simple way of getting details about the IP range
sipcalc 10.0.1.84 255.255.0.0
-[ipv4 : 10.0.1.84 255.255.255.0] - 0 [CIDR] Host address - 10.0.1.84 Host address (decimal) - 167772500 Host address (hex) - A000154 Network address - 10.0.1.0 Network mask - 255.255.255.0 Network mask (bits) - 24 Network mask (hex) - FFFFFF00 Broadcast address - 10.0.1.255 Cisco wildcard - 0.0.0.255 Addresses in network - 256 Network range - 10.0.1.0 - 10.0.1.255 Usable range - 10.0.1.1 - 10.0.1.254
The final example which is probably the most useful to people is to pass in an interface as the parameter
sipcalc -i eth0
-[int-ipv4 : eth0] - 0 [CIDR] Host address - 109.123.80.196 Host address (decimal) - 1836798148 Host address (hex) - 6D7B50C4 Network address - 109.123.80.0 Network mask - 255.255.255.0 Network mask (bits) - 24 Network mask (hex) - FFFFFF00 Broadcast address - 109.123.80.255 Cisco wildcard - 0.0.0.255 Addresses in network - 256 Network range - 109.123.80.0 - 109.123.80.255 Usable range - 109.123.80.1 - 109.123.80.254
