Website & HTTP Tools
Inspect how a web server responds to an external client: status codes, every redirect hop, response headers and timing, and a graded report of the security headers that protect your visitors.
For certificates and HTTPS configuration, use the SSL/TLS checker and the HSTS preload checker in the Security tools.
2 free website tools
Guides: Web & Mail Servers
- Postfix as a Relay, with MiltersConfiguring Postfix to relay for internal networks or through a smarthost with SASL auth, restriction stages (client/helo/sender/recipient/data), and wiring OpenDKIM/OpenDMARC/SpamAssassin as milters.
- Postfix postscreen and Pre-Queue Spam DefenseHow postscreen filters connections before smtpd, the deny/pass list, DNSBL weighting, deep protocol tests (pipelining, non-SMTP, bare newline), greylisting effect, and tuning to avoid false positives.
- Dovecot IMAP BasicsDovecot's role in a mail stack, Maildir vs mdbox, authentication and userdb/passdb, the LMTP hand-off from Postfix, SSL, and debugging login and delivery with doveadm.
- unbound as a Recursive ResolverRunning unbound for a LAN or a single host: DNSSEC validation, caching, access control, forwarding vs full recursion, local zones and overrides, DoT upstream, and prefetching.
- OCSP Stapling and Modern TLS ConfigA current TLS server config for Nginx and Apache: protocols and ciphers, OCSP stapling, session resumption, HSTS, OCSP must-staple, and testing with testssl.sh and the checker.
- HAProxy BasicsThe frontend/backend model, L4 vs L7 mode, balance algorithms, health checks, sticky sessions, ACL-based routing, TLS termination, and reading the stats page and logs.
Checking a whole domain? The Super Scanner runs every DNS, email, website and security check at once and gives one score.