fail2ban Filter Tester

Paste a failregex and sample log lines to see which match and what <HOST> would be banned — for iterating on a filter before deploying it.

failregex (one per line — a line is a hit if any matches)

Sample log lines

Approximation: <HOST>/<ADDR>/<IP> expand to an IP-or-hostname matcher, JS regex ≈ Python, and no timestamp/datepattern stripping is applied. Iterate here, then confirm with the real fail2ban-regex. A pathological pattern can hang this tab (ReDoS) — it all runs client-side on text you paste.