Code

For reasons™ I needed my own setup of a temporary and anonymous email server. All it needed to do is accept all incoming emails and store them in a database. To be on the safe side, only the smallest subset of RFC 5321 and not too much unnecessary program logic were implemented. As a result, less than 300 lines of erlang code are able to receive emails just fine.

Check out tmpmail on github.

Interesting observation: A few hours after starting the server, the first scanners started spamming or rather probing. The first few emails received contained a correct 'Received' header that would ordinarily have been inserted by the receiving end. Two months later four distinct To/From combinations send probes on a regular basis from different IPs. I guess this is botnet related. Never mind.

The actual purpose of this exercise was to be able to receive emails from software during a security audit, e.g. password recovery, registration confirmation, newsletters, status emails. For short-term analysis I prefer the python-script mailsink, but tmpmail is best suitable for long-term tests and provides permanent storage.

For years I have been using Nagios and later Icinga for monitoring my few servers and services. However working the setup did not fit perfectly. What I needed was:

• monitoring for very few servers (2-3)
• live check for very few services (10-20)
• easy and straight forward configuration via terminal
• set the time/interval for each check
• directly define a command to be executed for each check
• nice web overview without too much fuzz about it and not much of an attack surface
• XMPP notifications
• nagios plugin compatibility

What I can live without: - host groups - notification groups - complicated and extensive configuration - logging - remote check execution - a daemon

Even though there are many (many many many) monitoring solutions available, most are packed with features not needed here and rather difficult to deactivate. So I decided to write a simple and slim alternative: QMON.