Integrating FreeIPA authentication with GitHub Enterprise

The GitHub Enterprise – Using LDAP documentation lists FreeIPA as a supported LDAP service.

Although I was able to successfully test a basic LDAP connection, the test failed after I specified the Email (using value “mail”) and SSH key (using value “ipaSshPubKey”) fields. I received the following error: Continue reading Integrating FreeIPA authentication with GitHub Enterprise

ipactl error: Failed to start Directory Service: Command ‘/bin/systemctl start dirsrv@FREEIPA-OSRIC-NET.service’ returned non-zero exit status 1

Earlier today I got an alert that the LDAP service on my FreeIPA server was down. This was not long after I had received another alert that the drive space on the /var partition was critical. I logged on, freed up some drive space, and tried to start the service:

$ sudo ipactl start
Starting Directory Service
Failed to start Directory Service: Command '/bin/systemctl start dirsrv@FREEIPA-OSRIC-NET.service' returned non-zero exit status 1

I tried running systemctl directly to see the error message:

$ sudo systemctl start dirsrv@FREEIPA-OSRIC-NET.service

Continue reading ipactl error: Failed to start Directory Service: Command ‘/bin/systemctl start dirsrv@FREEIPA-OSRIC-NET.service’ returned non-zero exit status 1

ESXi upgrade from 5.5 to 6.7

ESXi 5.5 recently reached end-of-support (see End of General Support for vSphere 5.5), but my sales rep informed me that I was eligible for a free upgrade. Great! I set about doing just that.

First of all, I should note that you can’t upgrade directly from 5.5 to 6.7, so I upgraded to 6.5 first. I ran into several missteps along the way, which I have documented here: Continue reading ESXi upgrade from 5.5 to 6.7

Creating a histogram with Gnuplot

Gnuplot has plenty of examples on its histograms demo page. The demos use immigration.dat as a datasource, which you can find in gnuplot’s GitHub repository: immigration.dat data source.

While the examples demonstrate many of the available features, it’s not clear what some of the specific options do. You could read the documentation, but who has time for that? Some of us are just trying to create really simple histograms and don’t need to master the nuances of gnuplot.
Continue reading Creating a histogram with Gnuplot

Roomba 530 doesn’t hold a charge

I bought a refurbished Roomba 530 on Woot in 2009, and it’s been an indispensable part of the household ever since. Sure, the cat hates it, it regularly knocks things over, and it somehow escapes its constraints and sneaks off into other parts of the house, but the point is, it cleans while I do something else.

It’s always a satisfying moment when I start the dishwasher, the washing machine, and Roomba at the same time and shout, “Get to work, robots!” and then leave.

One fateful day in 2018, I spilled some water* and Roomba, hapless as ever, bee-lined straight into it. It stopped. Its light turned red. It sang out some tones in a minor key that fit the rhythm of, “Uh-oh. What have I done?”
Continue reading Roomba 530 doesn’t hold a charge

Postfix: altering the subject line of outgoing messages

Motivation: I’m changing my ticketing system so that messages with a friendlier subject line. Instead of ‘Subject: [SNAFU #1] summary’, I’ll change it to use ‘Subject: [HELPDESK #1] summary’.

Another colleague suggested we use procmail. As says:

Is procmail right for me?
Procmail is a serious unix hack. On the other hand, it does a pretty good job.


I think we can do better than a serious Unix hack. I think Postfix can handle this.

How to do it? Continue reading Postfix: altering the subject line of outgoing messages

Jekyll quick start: Error installing jekyll, failed to build gem native extension

I’m looking at starting another blog at, as a home for my impractical chatbots. I thought I should check out a blog software other than WordPress, since all of my infosec colleagues make fun of me for using it. One option on my list is Jekyll, which builds static sites. That’s great if you are worried about resources (i.e. super-cheap hosting) and security.

The Jekyll site includes a 4-step quickstart. Unfortunately, it failed for me at step #1:

Error installing jekyll, failed to build gem native extension

I’m running this on a Fedora 27 virtual machine that I spun up for testing Jekyll:

$ cat /etc/system-release
Fedora release 27 (Twenty Seven)

My Ruby version is up-to-date:

$ ruby --version
ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-linux]

Gem is installed and up-to-date:

$ gem --version

I took a closer look at the details of the error message:

gcc: error: /usr/lib/rpm/redhat/redhat-hardened-cc1: no such file or directory

I’m probably just missing a package, let’s see what package provides that file:

$ dnf provides redhat-hardened-cc1
Error: No Matches found

Fine, I let Google point me to a relevant StackOverflow post: G++ error:/usr/lib/rpm/redhat/redhat-hardened-cc1: No such file or directory

$ sudo dnf install redhat-rpm-config

I tried again:

$ sudo gem install bundler jekyll

It still failed, but with a different error:

make: g++: Command not found

I installed gcc+c++:

$ sudo dnf install gcc+c++

I tried to install Jekyll yet again:

$ sudo gem install bundler jekyll

That worked!

The following steps in Jekyll’s quickstart worked too:

$ jekyll new my-awesome-site
$ cd my-awesome-site
$ bundle exec jekyll serve

I copied my ~/my-awesome-site/_site folder to my document root (this can be automated with Jekyll, but I’m not there yet), and now, voila! my site is live:

Analyzing text to find common terms using Python and NLTK

I just recently started playing with the Python NLTK (Natural Language ToolKit) to analyze text. The book Natural Language Processing with Python is available online and is very helpful if you’re just getting started.

At the beginning of the book the examples cover importing and analyzing text (primarily books) that you import from nltk (Getting Started with NLTK). It includes texts like Moby-Dick and Sense and Sensibility.

But you will probably want to analyze a source of your own. For example, I had text from a series of tweets debating political issues. The third chapter (Accessing Text from the Web and from Disk) has the answers:

First you need to turn raw text into tokens:

tokens = word_tokenize(raw)

Next turn your tokens into NLTK text:

text = nltk.Text(tokens)

Now you can treat it like the book examples in chapter 1.

I was analyzing a number number of tweets. One of the things I wanted to do was find common words in the tweets, to see if there were particular keywords that were common.

I was using the Python interpreter for my tests, and I did run into a couple errors with word_tokenize and later FreqDist, such as:

>>> fdist1 = FreqDist(text)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'FreqDist' is not defined

You can address this by importing the specific libraries:

>>> from nltk import FreqDist

Here are the commands, in order, that I ran to produce my list of common words — in this case, I was looking for words that appeared at least 3 times and that were at least 5 characters long:

>>> import nltk
>>> from nltk import word_tokenize
>>> from nltk import FreqDist

>>> with open("corpus-twitter", "r") as myfile:
...     raw ="utf8")

>>> tokens = word_tokenize(raw)
>>> text = nltk.Text(tokens)

>>> fdist = FreqDist(text)
>>> sorted(w for w in set(text) if len(w) >= 5 and fdist[w] >= 3)

[u'Americans', u'Detroit', u'Please', u'TaxReform', u'Thanks', u'There', u'Trump', u'about', u'against', u'always', u'anyone', u'argument', u'because', u'being', u'believe', u'context', u'could', u'debate', u'defend', u'diluted', u'dollars', u'enough', u'every', u'going', u'happened', u'heard', u'human', u'ideas', u'immigration', u'indefensible', u'logic', u'never', u'opinion', u'people', u'point', u'pragmatic', u'problem', u'problems', u'proposed', u'public', u'question', u'really', u'restricting', u'right', u'saying', u'school', u'scope', u'serious', u'should', u'solution', u'still', u'talking', u'their', u'there', u'think', u'thinking', u'thread', u'times', u'truth', u'trying', u'tweet', u'understand', u'until', u'welfare', u'where', u'world', u'would', u'wrong', u'years', u'yesterday']

It turns out the results weren’t as interesting as I’d hoped. A few interesting items–Detroit for example–but most of the words aren’t surprising given I was looking at tweets around political debate. Perhaps with a larger corpus there would be more stand-out words.

Guest SSID surprises on home wireless router

My current home Internet provider is CenturyLink, and with that I’m using their recommended Zyxel C1100Z “modem”.

Via the modem’s web interface you can configure up to 4 SSIDs. I have one set up for my devices with strong security settings, and another set up for guests with weaker security settings. One thing that surprised me: when I checked the list of attached devices, devices attached to the guest SSID were allocated IP addresses in the same address range as, and could communicate with, devices attached to my trusted home SSID.

The Zyxel C1100Z will let you create LAN subnets with different IP address ranges and settings, but a device on one subnet can still communicate with devices on another LAN subnet. This would let you at least configure a host firewall (on hosts that support a host firewall) to drop traffic from a particular address range (e.g.

This is lunacy, though. Why would you create separate SSIDs with different security settings if the attached devices cannot be isolated from one another? I suspect that most users do not realize this. There are some settings you can change from one SSID to another, such as bandwidth throttling, but that seems like a secondary consideration to securing your network. Needless to say, my guest network has the same security settings as my trusted home network now.

I wondered if I had overlooked a setting somewhere, so I called to confirm with CenturyLink. The technician there was able to identify the SSIDs I had configured, suggesting that they have a backdoor into the modem they provided.

The moral of the story is: never use the equipment provided by your ISP.

Wifi on Raspberry Pi 3

I don’t run a GUI/Desktop on my Raspberry Pi devices. I don’t have monitors or keyboards connected to them — typically I log into them via SSH and manage them that way. I recently wanted to activate multiple network connections on my Raspberry Pi 3 Model B, so I decided to activate the wireless connection in addition to the wired connection that was already configured.

I tried following the steps at Setting WiFi up via the command line but got an error after the first step:

$ sudo iwlist wlan0 scan
wlan0     Interface doesn't support scanning : Network is down

I decided to check an see what devices were available via ifconfig:

$ ifconfig
eth0 ...
lo ...

No wireless device is listed there. I checked for all devices using the -a switch:

$ ifconfig -a
eth0 ...
lo ...
wlan0 ...

It’s there, wlan0, but it wasn’t active. I tried to bring the device up:

$ sudo ifconfig wlan0 up
SIOCSIFFLAGS: Operation not possible due to RF-kill

That error message is completely indecipherable to me! Fortunately, someone else had this error message too:
“SIOCSIFFLAGS: Operation not possible due to RF-kill”?

From that post I was able to determine that the wireless device was soft blocked:

$ sudo rfkill list
0: phy0: Wireless LAN
        Soft blocked: yes
        Hard blocked: no
1: hci0: Bluetooth
        Soft blocked: yes
        Hard blocked: no

How to unblock it? The following, described at the aforementioned post, worked. Although I’m not sure why I’m unblocking wifi instead of phy0:

$ sudo rfkill unblock wifi
$ sudo rfkill list
0: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no
1: hci0: Bluetooth
        Soft blocked: yes
        Hard blocked: no

$ sudo ifconfig wlan0 up
$ ifconfig
eth0 ...
lo ...
wlan0 ...

The device is now active, but we still need to connect. First, I generated an encrypted passphrase:

$ wpa_passphrase "my_network_id" "my_network_password"

Next, I appended that block of text to /etc/wpa_supplicant/wpa_supplicant.conf

Based on what I’ve read, that should be sufficient. The system should periodically detect changes to the wpa_supplicant.conf file and load the new settings automatically. I was impatient and rebooted. Apparently the following command should work too:

$ sudo wpa_cli reconfigure

After the reboot, I checked ifconfig for the wlan0 interface:

$ ifconfig wlan0 | grep 'inet addr'
          inet addr:  Bcast:  Mask:

It has an address — success!