Ansible is an OSS IT automation engine, in the vein of Chef and Puppet.
But what exactly can you do with it? John Gunkel filled us in.
He covered key concepts, package management, templates, roles,
GUI interfaces, and more!
RTFM: tcpdump(1) with Adam Thompson
Debugging an application's behaviour is sometimes easier to do by looking at
the interactions it has with other systems on the network
than by examining the application itself.
Modern UNIXes all come with a tool, tcpdump(1), that can examine, filter,
decode, and log all the traffic seen at a network interface -
whether it originates on that system or not.
Adam discussed the most common options for
tcpdump(1),
and demonstrated a simple example.
Many of us run some amount of Free and/or Open Source Software,
but how can we ever be sure that what we're actually running
was built from the allegedly published source code?
Whilst not a complete security solution in and of itself,
this project helps influence and improve security
and development as part of a wider set of policies.
Presented by Muz, this short talk introduced the issues with
trying to obtain reproducible builds,
and some of the work that has been done to date on certain code bases,
particularly with the Debian distro.
RTFM: netcat
A look into a computer networking utility for reading from and writing to
network connections using TCP/IP protocol,
designed to be a reliable "back-end" tool that can be used directly
or easily driven by other programs and scripts.
Note that there are two versions of netcat (or the nc command)
that are widely available: the traditional
"Hobbit" netcat(1),
and the ncat(1) command
that comes as part of Nmap.
This presentation by Wyatt Zacharias focused on the latter.
(Adam Thompson focused on the former in a
June 2014 RTFM.)
Love 'em or hate 'em, captive portals are widely used
to restrict Internet access to authorized users.
What if you need to set one up, but all the "canned"
solutions aren't quite right for your use case?
This presentation by Gilbert Detillieux showed
the various components that make up a captive portal,
and how you can set one up from scratch,
using Linux Netfilter/iptables,
ISC DHCPD and BIND,
the Apache web server,
and some custom back-end scripting.
Gilbert has made his presentation slides, in
PPTX and
PDF format,
available online.
RTFM: date
The lowly
date(1)
command has been a fixture of UNIX systems from the very early days.
Yet there may be features in this command that would surprise you.
Adam Thompson presented this RTFM,
and compared features of the date command from various systems,
including Solaris, OpenBSD, macOS, and GNU/Linux.
A short demonstration of the Unix
time(1)
command by Wyatt Zacharias.
Time is used to determine the duration of execution of a particular command.
Wyatt's presentation covered both the built-in time command in
bash(1),
and the external (GNU) time command,
including default and explicit output formatting in each.
Wyatt also talked about the
which(1) command,
as well as the bash-built-in type command,
that you can use to find out if a specified command is built-in or not.
(There was also mention of quoting the command name,
e.g. by preceding it with a "\", to bypass built-ins,
and of using explicit pathnames to distinguish between multiple external
commands with the same name.)
Round-table, Mingling and Munchies
As 2018 drew to a close,
MUUG continued our recent tradition of
turning the December meeting into more of a social event.
Cookies and pop were provided by MUUG,
but members were encouraged to bring their own finger food to sample and share.
Winnipeg Harvest Food Drive
Also as in previous years,
we combined our pot luck with a food drive for Winnipeg Harvest.
Cash donations were preferred this year as every $1 Winnipeg Harvest receives,
they are able to pick up and deliver $20 worth of groceries.
MUUG members were generous again in both their cash and food donations.
oVirt is a KVM based virtualization solution by Red Hat
which works on a data-centre / multi-server scale.
Mark Jenkins showed that you don't need a rack full of servers
or a SAN to try it out or simulate a production environment.
The secret sauce for this is nested KVM.
Cacti
is an open-source, web-based network monitoring and graphing tool
designed as a front-end application for the data logging tool RRDtool.
Cacti allows a user to poll services at predetermined intervals
and graph the resulting data.
Wyatt Zacharias gave us a new look at this software with his demo.
RTFM: systemctl(1)
Most Linux distros have now adopted systemd
as the new init process.
Gilbert Detillieux introduced the very basics of using
systemctl(1)
to control services in a systemd-based environment,
and showed a few useful options and features.
March 12, 2019: A Looking Glass Server with OpenBSD and OpenBGPD
Adam Thompson talked about setting up a
BGP Looking Glass server quickly using
OpenBSD and
OpenBGPd,
as well as how he used the UNIX "toolkit" to solve some
BGP analysis and visualization problems.
The presentation (which was quite a bit longer than the setup time)
included many interesting tangents about
OpenBSD support, installation, and configuration,
VMware configuration for BSD variants,
what good (vs bad or missing) man pages should look like,
setting up SSL certificates using
letsencrypt,
the Manitoba ISP landscape,
and much more.
Adam has made his presentation slides, in
PPTX and
PDF format,
available online.
The round-table discussion at the start of the meeting covered many,
varied topics, including
dealing with frozen pipes (literally),
and running a pipeline filter conditionally only if there's output
(solution is to use the
ifne(1)
command, which is usually part of an optional "moreutils" package
in several Linux distros).
Kevin McGregor covered the state of the WINE project,
software which enables you to run Windows software unaltered
on Linux-based systems,
and of a commercially supported version of it called Crossover.
Kevin's presentation included a demo of installing a Windows app,
Notepad++, under WINE.
RTFM: xargs(1) Redux^2
Adam Thompson once again turned his attention to
xargs(1),
and demonstrated scripting techniques that allow parallel processing
using nothing but standard UNIX tools,
and the xargs -P option.
Wyatt Zacharius showed us Amazon Virtual Private Cloud (Amazon VPC)
which lets you provision a logically isolated section of the AWS Cloud
where you can launch AWS resources in a virtual network that you define.
You have complete control over your virtual networking environment,
including selection of your own IP address range, creation of subnets,
and configuration of route tables and network gateways.
RTFM: Stupid Bash Tricks
Members were amazed, delighted, and confused by Katherine Scrupa,
as she showed odd things you can do in Bash.
June 11, 2019: PDF::Reuse - Reuse and Mass-produce PDF Documents
Brad Vokey demonstrated a Perl module,
PDF::Reuse,
that specializes in mass-producing
efficient multi-page PDF documents
by reusing an original PDF file as a template.
This module was the perfect tool to help him create many multi-page PDF
result forms for his Matchomatics business (with many over 1000 pages each)
quickly and easily while at the same time
keeping file sizes small and efficient.
RTFM: pstree(1) and a few other tricks
Gilbert Detillieux did an off-the-cuff presentation on the
pstree(1) command,
showing some potentially useful features of the command,
and talking about different options in different implementations,
available (either in the distro or as an add-on) on different platforms.
Adam Thompson talked about some tricks to keep two systems with
Ansible playbooks
in synch, in such a way that either can be the "master"
and act as a backup for the other.
And finally, after his presentation, Brad Vokey demonstrated a web site,
wttr.in,
that displays the current weather for your location
using only UTF-8 characters in the output,
so it can be run from the command line,
(e.g. curl wttr.in).
