Security Puppy is a personal blog, talking about security (and mainframes too!).

My name is Hartanto, I’m a student from Singapore who proudly say “COBOL is Amazing!” Learning COBOL has been a valuable lessons which not only adds a technical skills to my resume, but also introduces me to the wonderful community of mainframes.

In the community, I’m around to help others, especially with regards to Master the Mainframe and Open Mainframe Project’s COBOL Programming Course.

Find out more about me formally on my profile site.

Contact Me

I’m reachable via email at .