About sysadmin.lk
sysadmin.lk is a free toolkit for system administrators, DevOps engineers and anyone who has to answer "why is my mail bouncing?" or "is this certificate about to expire?" quickly. The DNS, email, SSL/TLS, network and website checks run from our servers; the utilities run in your browser.
Who builds it?
sysadmin.lk is built and run by Prabath Thalangama, a Tech Lead at Omobio with more than ten years of deploying, supporting and managing Linux-based systems, and Red Hat, AWS, Kubernetes, Terraform and Microsoft certifications, and a University of Colombo alumnus.
The site started in 2014 as a notebook. Joining a telecom value-added-services team with only a few Linux commands to go on, Prabath bought the domain and wrote down each new thing learned, and kept doing it through roles at LSEG and Omobio, from ls to oVirt, AWS and Kubernetes. The blog still gets that traffic, so the tools were added to give its readers something they can use every day.
Connect on LinkedIn, or send a message through the contact page.
Why do these tools exist?
Most diagnostic sites show a raw record and a pass or fail. That is enough when you already know the protocol, and not enough when you don't. Every check here is meant to say what was tested, what was found, why it matters and how to fix it, with the relevant RFC linked so you can verify the advice yourself.
How do the checks work?
- Network checks run in background workers with a timeout on every request, so a slow target can't hang the site.
- Every target is validated before anything connects to it. Private, loopback, link-local and cloud metadata addresses are refused, including when a hostname or redirect resolves to one.
- DNS checks resolve through our servers, registration data comes from RDAP, the blacklist checker queries more than 80 public DNSBLs, and the SSL checker verifies the full certificate chain and host name the way a browser does.
- Scores follow fixed, published rules. The methodology page lists every deduction.
What do we store?
Lookups made without an account aren't tied to any identity. Browser-based tools (password and key generators, JWT, JSON, XML, YAML) send nothing to us. If you create an account, your monitors and scan history are kept until you delete them, and you can export or delete everything yourself. The privacy policy has the details.
Can I use the tools from scripts or AI agents?
Yes. The same checks are available over a JSON API, documented on the developers page.