IP ops provides IP and VLSM calculator written in Java.
Features
- from address and mask calculates broadcast of this network, network address, first and last useable IP address of this network and number of useable IPs
- results in deciaml and binary format
- converting long masks to CIDR format and reversely
- adding and subtracting value to IP address
- address inversion
- logical AND and OR of addresses
- from IP adress, mask, number of subnets and IP addresses on each subnet it calculates network addresses, variable masks, broadcasts and IP ranges for subnets


