A simplistic and secure Gemini server

Vger is a gemini server supporting chroot, virtualhosts, default language choice and MIME types detection.

Vger design is relying on inetd and a daemon to take care of TLS. The idea is to delegate TLS and network to daemons which proved doing it correctly, so vger takes its request from stdin and output the result to stdout.

The average setup should look like:

         client
           ↓           TCP request on port 1965
       relayd or haproxy
       or stunnel on inetd
           ↓           TCP request to a port of choice on localhost
       vger on inetd

Vger is perfectly secure if run on OpenBSD, using unveil() the filesystem access is restricted to one directory (default to /var/gemini/) and with pledge() only systems calls related to reading files and reading input/output are allowed.

Get the sources

git clone https://tildegit.org/solene/vger.git

Running tests

Vger comes with a test suite you can use with make test.

Some files under /var/gemini/ are required to test the code path without a -d parameter.

Command line parameters

Vger has a few parameters you can use in inetd configuration.

• -d PATH: use PATH as the data directory to serve files from. Default is /var/gemini
• -l LANG: change the language in the status return code. Default is en
• -v: enable virtualhost support, the hostname in the query will be considered as a directory name.
• -u username: enable chroot to the data directory and drop privileges to username.

How to configure Vger using relayd and inetd

Create directory /var/gemini/ (I'd allow this to be configured later), files will be served from there.

Add this line to inetd.conf:

11965 stream tcp nowait gemini_user /usr/local/bin/vger vger

Add this to relayd.conf

log connection
relay "gemini" {
    listen on hostname.example port 1965 tls
    forward to 127.0.0.1 port 11965
}

Make links to the certificates and key files according to relayd.conf documentation

# ln -s /etc/ssl/acme/cert.pem /etc/ssl/hostname.example\:1965.crt
# ln -s /etc/ssl/acme/private/privkey.pem /etc/ssl/private/hostname.example\:1965.key

Enable inetd and relayd and start them:

# rcctl enable relayd inetd
# rcctl start relayd inetd

Todo

• add syslog traces
• maybe a chroot() for non OpenBSD systems.