BSDStammtisch Wien 0x02 2018-03-13

Past meeting 🗓

Tuesday, 2018-03-13, 19:00 (CET)

Location 🗺

Seminarraum Technische Informatik, Operngasse 9, 1040 Wien
Public Transport: U1, U2, U4 Karlsplatz, Bus 59A Bärenmühldurchgang, Nightline N60, N62, N66, N71, Tram 2 (within reasonable walking distance)
Bicycle parking: Just around the corner

Attendance 🎟

Free for all people interested in learning or discussing about all things BSD! You are welcome!


  • FreeBSD Jails, jails.conf and jail networking
  • Please present your topic!
  • Show and Tell
    • Show us your quick tips and tricks, the tools you use or recently discovered, be it CLI, GUI, web services, that chocolate chip cookie recipe, a book or conference recording, anything goes. No need to prepare anything.
  • Chit chat, food and drinks afterwards

Shownotes 📝



  • What has happened since the last BSDStammtisch?
    • We can haz new Logo, already in use on Twitter and Mastodon
    • MacLemon didn't manage to get the website styled in time, sorry for that. It's on the plan for our April meeting.
  • We now have a standard .ics calendar you can subscribe to, so you never miss a meeting! Calendar subscription for BSDStammtisch Wien There are no alerts or reminders in that calendar, we respect the privilege granted by being in your calendar.

Main Topic: Jails, jails.conf and jails networking

Thanks to karu and dch for the huge influx of jail related info in their talks! Thanks to everbody for sharing big and small tips for Show and Tell!

Slides will be made available!

FreeBSD Jails in the Handbook

Jails related commands and files

Focusing on the Jails and networking part that is covered with the base system.

A brief history of Jails:

jails are just chroot on steroids. As they are basically an extension of the chroot function they feel a bit weird at times today.

jails are used as system containers today despite their original use case as single app containers. jails normally should have the securelevel=3 (strongest), except you have a good reason to choose another level. The not-so-sane default is securelevel=-1.

Info on how FreeBSD handles Securelevels

Jail integration for userland tools

Many command line tools are integrated and know about jails. - top(1) - htop(1) - zfs(8) - ps(1) - pkg(8)

Security considerations for networking

A jail picks its first IPv4|IPv6 address to map the loopback IP (or more specifially 127/8) and ::1/128. So the sane way to assign IPs to jails is to first assign a loopback IP on a cloned interface like lo1 and as a secondary IP you assign the public or local (HOST-side-IPv4-LAN) address and IPv6 addresses. That way you make sure to not expose any daemons that bind their management interface to the loopback believing that this interface is not exposed to the public internet.

If you do not set skip on lo1 you can finely control which jail is allowed to talk to which other jail and on which ports.

Managing Jails with zjail(8)

Even easier than ezjail, zjail lays bare the very fabric of FreeBSD jails.
DIY-Jails by dch.

Show and Tell

Short introductions to tools you like, or that solve a problem for you. This can be anything from GUI, CLI to Webservices, a book, a podcast or conference recording you'd like to recommend or a recipe for chocolate chip cookies. Mmmhhmmmm Cookies! 🍪 No need phor a phanphy prphentaishn.

Security Testing of Websites:
  • Firefox extension for playing with Content-Security-Policy
  • Chromium|Chrome Extensions for playing with Content-Security-Policy
  • SSLLabs to test the HTTPS of your site and find bugs. For example the site
  • Check HTTP Security Headers to instruct browsers to activate certain security features. BSDStammtisch Security Headers
  • Generate a good Content Security Policy for your site with the CSP Generator
    • The browser console is your friend to find compatibility problems with different browsers since the do not support all the fancy stuff each.
  • Maintain Wordpress installations from the command line with WP-CLI (not available in ports, but reasonable to install and maintain.)
  • To test your Wordpress site for known vulnerabilities you can use WPScan which is built in Ruby.
Security Testing of XMPP/Jabber Servers (S2S, C2S)
CLI tools
Video recommendations
Jail security

Upcoming events (in chronological order)

Past events

Drinks and Food afterwards

Thanks to Fachschaft Informatik for hosting us and providing cold beverages. Thanks for supporting the BSDStammtisch in Wien!