Add a container for osuosl's smtpd tls auditor.

osuosl-auditor/Dockerfile

+FROM docker.io/library/debian:10
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update
+RUN apt-get -y upgrade
+RUN apt-get -y install curl
+
+RUN curl -L https://omnitruck.cinc.sh/install.sh | bash -s -- -P cinc-auditor -v 4
+
+RUN apt-get clean all
+
+CMD cinc-auditor exec \
+  --input ssl_host=mailfish.xiph.org ssl_port=[25,465] \
+  -l info \
+  https://github.com/osuosl/osuosl-baseline/archive/main.tar.gz
+
+# Run with e.g.
+# podman run --rm osuosl-auditor

osuosl-auditor/README.md

+# OSUOSL's smtpd auditor
+
+This is a script to audit the TLS config of mailservers.
+It uses the cinc project's auditor packages, compatible
+with chef, and a rule set downloaded from osuosl.org.
+
+There's also a `docker.io/cincproject/auditor` image, but
+it doesn't support aarch64, and of course doesn't have our
+local default command line.
+
+To build the image
+(Subsitute `docker` for `podman` if you prefer that tool.)
+```
+podman build -t osuosl-auditor .
+```
+
+
+Invoke with bare arguments to check the default mailserver:
+```
+podman run --rm osuosl-audior
+```
+
+Invoke against a different host or ports:
+```
+podman run --rm osuosl-audior cinc-auditor exec \
+  --input ssl_host=hostfish.xiph.org ssl_port=[25,465] -l info \
+  https://github.com/osuosl/osuosl-baseline/archive/main.tar.gz
+```