This is solution of IP Addr Counter test assignment.

Build:

javac -d build/class src/*.java
jar cfm build/ip_count.jar manifest/MANIFEST.MF -C build/class .

Run:

java -jar build/ip_count.jar <path/to/file>

Result of run on example file, measured with time utility:

IP count is: 1,000,000,000

real    5m15,076s
user    4m43,477s
sys     0m31,540s