Quick and dirty copies of website with wget.

Jan 14 2018

Let's say there's a website that you want to make a local mirror of.  This means that you can refer to it offline, and you can make offline backups of it for archival.  Let's further state that you have access to some server someplace with enough disk space to hold the copy, and that you can start a task, disconnect, and let it run to completion some time later, with GNU Screen for example.  Let's further state that you want the local copy of the site to not be broken when you load it in a browser; all the links should work, all the images should load, and so forth.  One of the quickest and easiest ways to do this is with the wget utility.

Automating deployment of Let's Encrypt certificates.

Jan 06 2018

A couple of weeks back, somebody I know asked me how I went about deploying SSL certificates from the Let's Encrypt project across all of my stuff.  Without going into too much detail about what SSL and TLS are (but here's a good introduction to them), the Let's Encrypt project will issue SSL certificates to anyone who wants one, provided that they can prove somehow that they control what they're cutting a certificate for.  You can't use Let's Encrypt to generate a certificate for google.com because they'd try to communicate with the server (there isn't any such thing but bear with me) google.com to verify the request, not be able to, and error out.  The actual process is complex and kind of involved (it's crypto so this isn't surprising) but the nice thing is that there are a couple of software packages out there that automate practically everything so all you have to do is run a handful of commands (which you can then copy into a shell script to automate the process) and then turn it into a cron job.  The software I use on my systems is called Acme Tiny, and here's what I did to set everything up...

Quick and easy SSH key installation.

Dec 27 2017

I know I haven't posted much this month.  The holiday season is in full effect and life, as I'm sure you know, has been crazy.  I wanted to take the time to throw a quick tip up that I just found out about which, if nothing else, will make it easier to get up and running on a Raspberry Pi that you've received as a gift.  Here's the situation:

You have a new account on a machine that you want to SSH into easily.  So, you want to quickly and easily transfer over one or more of your SSH public keys to make it easier to log in automatically, and maybe make running Ansible a bit faster.  Now, you could do it manually (which I did for many, many years) but you'll probably mess it up at least once if you're anything like me.  Or, you could use the ssh-copy-id utility (which comes for free with SSH) to do it for you.  Assuming that you already have SSH authentication keys this is all you have to do:

[drwho@windbringer ~]$ ssh-copy-id -i .ssh/id_ecdsa.pub pi@jukebox
/bin/ssh-copy-id: INFO: Source of key(s) to be installed: ".ssh/id_ecdsa.pub"
/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out
    any that are already installed
/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now
    it is to install the new keys

pi@jukebox's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'pi@jukebox'"
and check to make sure that only the key(s) you wanted were added.

Now let's try to log into the new machine:

[drwho@windbringer ~]$ ssh pi@jukebox
Linux jukebox 4.9.70-v7+ #1068 SMP Mon Dec 18 22:12:55 GMT 2017 armv7l

The programs included with the Debian GNU/Linux system are free software;

# I didn't have to enter a password because my SSH pubkey authenticated me
# automatically.
pi@jukebox:~ $ cat .ssh/authorized_keys
ecdsa-sha2-nistp521 AAAAE....

You can run this command again and again with a different pubkey, and it'll append it to the appropriate file on the other machine (~/.ssh/authorized_keys).  And there you have it; your SSH pubkey has been installed all in one go.  I wish I'd known about this particular trick... fifteen years ago?

Administering servers over Tor using Ansible.

Dec 02 2017

Difficulty rating: 8.  Highly specific use case, highly specific setup, assumes that you know what these tools are already.

Let's assume that you have a couple of servers that you can SSH into over Tor as hidden services.

Let's assume that your management workstation has SSH, the Tor Browser Bundle and Ansible installed.  Ansible does all over its work over an SSH connection, so there's no agent to install on any of your servers.

Let's assume that you only use SSH public key authentication to log into those servers.  Password authentication is disabled with the directive PasswordAuthentication no in the /etc/ssh/sshd_config file.

Let's assume that you have sudo installed on all of those servers, and at least one account can use sudo without needing to supply a password.  Kind of dodgy, kind of risky, mitigated by only being able to log in with the matching public key.  That seems to be the devopsy way to do stuff these days.

Problem: How to use Ansible to log into and run commands on those servers over the Tor network?

Keybase and Git.

Nov 27 2017

A couple of weeks ago a new release of the Keybase software package came out, and this one included as one of its new features support for natively hosting Git repositories.  This doesn't seem like it's very useful for most people, and it might really only be useful to coders, but it's a handy enough service that I think it's worth a quick tutorial.  Prior to that feature release something in the structure of the Keybase filesystem made it unsuitable for storing anything but static copies of Git repositories (I don't know exactly waht), but they've now made Git a first class citizen.

I'm going to assume that you use the Git distributed version control system already, and you have at least one Git repository that you want to host on Keybase; for the purposes of this example I'm going to use my personal copy of the Exocortex Halo code repository on Github.  I'm further going to assume that you know the basics of using Git (cloning repositories, committing changes, pulling and pushing changes).  I'm also going to assume that you already have a Keybase account and a fairly up-to-date copy of the software installed.  I am, however, going to talk a little bit about the idea of remotes in Git.  My discussion will necessarily have some technical inaccuracies for the sake of usability if you're not an expert on the internals of Git.

Cleaning up Firefox... somewhat.

Sep 04 2017

Chances are you're running one of two major web browsers on the desktop to read my website - Firefox or Google's Chrome.

Chrome isn't bad; I have to use it at work (it's the only browser we're allowed to have, enforced centrally).  In point of fact, I'd have switched to it a long time ago if it wasn't for one thing.  I make heavy use of a plugin for Firefox called Scrapbook Plus, which make it possible to take a full snapshot of a web page and store it locally so that it can be read offline, annotated, and full-text searched.  I never count on having connectivity (I live in the United States, after all, and right now my home connection is running quite poorly and has been for several days due to an ongoing situation at my local CO) so I try to keep both essential documentation and reading material in general stored locally for those dry periods.  However, there is no port of Scrapbook Plus for Chrome, nor is there a workable equivalent addon for same (I think I've tried them all).  I'm not about to do without my traveling hoard of information (which at this time numbers around 10,000 unique web pages and 15 gigabytes of disk space).  Out of desperation last night I did some research into how I might be able to speed up Firefox just a little and get more use out of it until I figure out what to do.  Here's what I found: