I have just published the latest release for the Thunderbird plugin Lookout-fix-version.

This is a bug fix issue

Fixes are for the ics parsing

Added quick decompose_rfc822_address sanity check

Occasionally a phrase without any email addresses is used in the attendee fields and this can cause the complex regex in the decompose_rfc822_address function to freeze. As I couldn't come up with a sensible alternative (primarily due to lack of windat samples) I added a simple sanity check prior to the regex.

Added special character skip for ICS attendee data

Occasionally a special non printing character will be decoded, x20 to x7E, causing the ics file to become unreadable. Lookout now ignores these invalid fields.

Added zero( 0 ) UID check

Sometimes the UID will be decoded as 0 rather than null, if this happens lookout will now attempt one of the other UID methods as intended.

You can download this update from the Github Release page or the Thunderbird addon page

In august 2018 I took over maintenance of the Thunderbird addon [Lookout-fix-version][e7c45433]. I soon set up a the Github Organization TB-throwback so that future development can be expanded and transferred easier if I stop work on it.

It's been an interesting experience managing a small project that's over 11 years old. Especially with all the changes and rapid development Thunderbird has been going experiencing now it's separated from Mozilla.

Why did I take over?

I needed to move my office away from Outlook 2010. I had no budget to upgrade the office software, but I couldn't allow the company to keep limping along with a 9 year old product.

Thunderbird to the rescue! Except...

TNEF files, supposedly a thing of the past. Even Microsoft recommends you NOT to send such files. But we have to work with people who don't upgrade and pay the lowest bidder to configure their exchange servers.

Unfortunately the original Lookout was at this point unmaintained and severly out of date similarly Lookout+ and Lookout-fix-version hadn't seen any updates in a long time. luckily Oleksandr was still contactable via the support email and was happy to add me as a developer on the ATN page.

My first change was a simple modification to the preferences css to fix changes in Thunderbird 59. I've since been working on adding debugging, improving performance, squashing bugs and generally attempting to learn how everything is strung together.

I plan on porting the addon to a webextension in the coming months to ensure we have this useful addon for many years to come.

I often see questions on /r/selfhosted on how to secure a server. Here is a quick checklist of things you might want to look into.

Follow best practices for the basics

• Verify your install images using gpg and sha256
• Use strong passwords, defiantly think about using a password manager like KeePass
• Don't use the same password for root and the regular user.
• Don't run scripts/applications using sudo/su where possible.
• Learn linux permissions to avoid using sudo/su where possible.
• Use SSH Public Keys
• Regularly Update

Lock down the Server

• Disable root login via SSH
• Close all unused incoming ports via UFW/iptables
• Limit outgoing ports as well as incoming using UFW/iptables
• Watch for credential stuffing/brute force attacks with Fail2ban

Backup your configs/files

• Securely encrypted backup via Duplicity
• External Backup to external drive.
• Remote backup, either via a regularly swapped out external drive or via the cload

Set up monitoring services to let you know when something goes wrong

• Send email on syslog message
• Set up notifications for when updates are available
• Monitor system critical files with Tripwire
• Set up ssh login notifications with gotify
• Set up Graylog or a similar system log aggregator in order to do log analysis

Here are a few extra things you can do to bolster your ssh security

• Use a non standard port, this stops like 80% of the dumb bots
• Enable geo-blocking on your ssh port, easy to do in pfsense using the package PFBlockerNG or with iptables
• Close you ssh port based on the time, will you ever really need to ssh in at 3am? Possibly
• Add 2FA using google-authenticator-libpam this should stop 99% of brute force attacks
• Use something like fwknop for encrypted port knocking - best to avoid unencrypted port knocking using knockd

Useful resources

• Linux man pages
• Digital Ocean tutorials
• nixCraft tutorials
• crontab wizard
• Ubuntu wiki

This morning I received a link in Facebook messenger from an old friend, someone I haven't spoken to in years. It was obviously a phishing link, the title was wrong "Dugite is this a video of you?" and the preview image was blurry, like it was stuck not loading.

Needless to say I didn't click and messaged them back saying "Probably should change your password?"

What Interests me is the reaction when this friend posted on their wall, within minuets, not to open any messages from them and they "HAVE A VIRUS ON MY PHONE". Out of 7 people 3 opened the obviously shady link.

Not one of these people who opened this link mentioned they will now need to change their password, in fact one person even said it all should be ok once it's gone through their entire address book. The non-technical people, to me at least, seem to be treating phishing and malware like you would the common cold. It'll pass, fact of life and not a real concern.

They of course should be very concerned with the majority of web browsing occurring on the mobile the amount of data that is potentially stored on a phone is astronomically large. From your banking app to your photos and everything you can gain access through your email accounts is at risk. Mobile operating systems are, thankfully, very locked down with each app operating somewhat isolated from the others, but that's not a guarantee.

I fear the next decade of tech breaches are going to get ugly and there just isn't a technical solution to user apathy.

Now for the obligatory static blog post on any static blog This blog is a Nikola static blog, a python based static blog generator.

Why did I choose Nikola?

1. It's Python based - I like python, I know python, and I can hack python. Jekyll, the most popular static blog generator, is written in Ruby. I found it to be slow and painful to work with. I couldn't be bothered learning it's particulars. Also my Desktop and Server came with python so there was no barrier to entry.
2. Batteries are Included - I looked at the popular Pelican, it's arguably more flexible and powerful than Nikola, but you have to do more initial configuration. I had already been procrastinating on re-starting my blog for over a year, I needed to get started

Why do people like Static Blogs?

1. You need to be savvy - Static Blogs scratch the tech tinkering itch, don't like something it's simple to change that.
2. It's simple - Many CMS systems are over complicated messes, overkill for the typical blog. Do you need to render your blog on the fly for each visitor? PHP is useful but if you don't need it why use it?
3. Portable - You render your site as it changes, have beef with your service provider? Change your dns and upload with next to no configuration. Done
4. It's Fast - How fast can a server trow out a few kb of static html? Very fast! With Wordpress you need to install caching plugins to make your site essentially static, why not skip the middle man and do it from the start.
5. You write how you like - Markdown, reStructuredText, MediaWiki Markdown or even HTML.
6. It's secure - No database to hack, no PHP to patch.

Why do people hate Static Blogs?

1. No web based content management system - This is something that tends to be lacking in any static blog. It's static after all! There are many ways to get around this by using something like Netlify CMS. Personally I'm using the Atom test editor and will be going over this in a future post.
2. You need to be savvy - As a general rule you need to be able to deal with the nuts and bolts of your blog. This is a good and bad thing, depending on your disposition.

For your ssh you can use google-authenticator-libpam to add time based codes to your ssh login.

On debian/ubuntu:

    sudo apt update && sudo apt install google-authenticator-libpam

    google-authenticator

    Do you want authentication tokens to be time-based (y/n) y
    [...]
    Do you want me to update your "/home/dugite/.google_authenticator" file? (y/n) y
    [...]

You will see a QR code/secret key that you can scan with a TOTP app like andotp, authy or google authenticator (WARNING Google authenticator has no backup options). There are also your emergency scratch codes.

In /etc/ssh/sshd_config Add:

    # Use Challenge Response Auth i.e. TOTP
    ChallengeResponseAuthentication yes
    # Require both publickey and TOTP
    AuthenticationMethods publickey,keyboard-interactive

In /etc/pam.d/sshd

    # Comment out Standard Un*x authentication.
    # @include common-auth
    # Load the google TOTP Authentication module
    auth required pam_google_authenticator.so

Google, once the tech enthusiast darling is looking more and more like Microsoft did in the mid 90's.

Google to restrict modern ad blocking Chrome extensions to enterprise users

Google is first and foremost an ad company so it should come as no surprise that now they are leading the browser market share

Now Microsoft is switching to chromium as a browser backend it's no surprise we see Google moving to limit Ad-blockers.

Google is eating our mail

Google really got entrenched with the tech enthusiast crowd because gmail was free, quick and had good spam filtering. Now we are all feeling the consequences of encouraging non-technical people to centralize their emails with them. A once open and vibrant standard is increasingly looking like a mono-culture with both Google and Microsoft's opaque filtering and non-standard blocking making running your own email server almost impossible. Along with the launch of google's AMP for email we see yet another example of Google pushing through their own interests over the interests of the email ecosystem.

What you can do

• Switch to Firefox
• Switch to alternative search engines like Duckduckgo
• Use more privacy respecting tools

UPDATED Thanks to sk@0x in the comments for the bits I missed

In my last post I described how I decrypt my home server remotely with ssh. Today I would like to share how I like to lock/unlock my ssh port with an encrypted port knocking implementation fwknop

The issue with port knocking

On the face of it port knocking looks like a good idea. Lock down your ssh port until you need it, avoiding any zero day issues with the ssh protocols. The problem is this, port knocking is sent in the clear over the network. Anyone looking can see your knock "code", much like if you had a secret door knock some one around the corner could heard the pattern of your knocks.

This is where fwknop comes in, it's SPA (Single Packet Authorization) cannot be re-sent it is one time only. Not to mention it's faster as you are only sending the one packet.

The main issue I had with fwknop is by default you have to specify the source IP address you want to be able to access your server. I found this to be quite painful to set-up, so I found a simple way around the issue.

Note: this only works if you are blocking ports by default. I use UFW to simplify that process. See this Digital Ocean tutorial on the basics of UFW

Server Side:

In Debian based systems fwknop is split into fwknop-client and fwknop-server. We will want both of them

sudo apt install fwknop-server fwknop-client

First we need to enable the fwknop server in the /etc/default/fwknop-server file. by changing the line START_DAEMON="no"

# Default settings for fwknopd.

# Change it to yes if you would like fwknopd to be started at boot time.
#
# START_DAEMON="no"
START_DAEMON="yes"

# Add any options you would like to pass to the daemon when started
# For example if you would like to add an override file for your setup, this
# can be achieved this way:
#
#     DAEMON_ARGS="--override-config /root/fwknopd.override.conf"
DAEMON_ARGS=""

Next we need to set up the basic config rules on the server found in /etc/fwknop/fwknopd.conf Debian and Ubuntu have changed the default interface name from eth0 to enp3s0 so we have to set that. We can also change the listening port here.

PCAP_INTF               enp3s0;

# change your port to your desired listening port.
PCAP_FILTER                 udp port 62201;

Now we use fwknop to generate our key's. We could use GpG here, but I didn't feel the extra encryption brings much to the table as we are only opening the ssh port and I have public key authentication and TOTP enabled.

fwknop -A tcp/22 -D example.tld --key-gen --use-hmac --save-rc-stanza

You can now find the KEY_BASE64 and HMAC_KEY_BASE64 in ~/.fwknoprc we will need these for the /etc/fwknop/access.conf file and the client.

In the /etc/fwknop/access.conf file. Note: I substituted the iptable commands for ufw commands. We don't have to worry about our ssh session being kicked as once it's connected the CMD_CYCLE_CLOSE (at least with ufw) won't close the existing connection.

SOURCE                          ANY

# Limit the Ports able to be opened
OPEN_PORTS                      tcp/22

# Keys from ~/.fwknoprc
KEY_BASE64                      [...]
HMAC_KEY_BASE64                 [...]

# Optionally use iptables
# CMD_CYCLE_OPEN                /sbin/iptables -A INPUT -p $PROTO --dport $PORT -j ACCEPT
# CMD_CYCLE_CLOSE               iptables -D INPUT -p $PROTO --dport $PORT -j ACCEPT

CMD_CYCLE_OPEN                  /usr/sbin/ufw allow $PORT
CMD_CYCLE_CLOSE                 /usr/sbin/ufw delete allow $PORT

# Default cycle time Mandatory for CMD_CYCLE_OPEN/CLOSE
CMD_CYCLE_TIMER                 180

A word of warning, fwknop can run arbitrary commands if ENABLE_CMD_EXEC is enabled. I don't see why you would ever really want to do that. You can also run any bash script from CMD_CYCLE_OPEN and CMD_CYCLE_CLOSE with the optional variables $PROTO, $PORT and $SRC. You can potentially get yourself in a lot of trouble if you do this so proceed with caution.

Now we need to setup the systemd file /etc/systemd/system/fwknop-server.service. Note: on a ubuntu (18.04.4 LTS) install I had to create the folder /var/fwknop/.

NOTE: sk@0x in the comments also mentioned the PID file needs to be in /run/fwknop dir in Ubuntu 20.04

[Unit]
Description=Firewall Knock Operator Daemon
After=network-online.target

[Service]
Type=forking
PIDFile=/var/fwknop/fwknopd.pid
ExecStart=/usr/sbin/fwknopd
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

Then we just enable and start the service

sudo systemctl enable fwknop-server.service && sudo systemctl start fwknop-server.service

Running sudo systemctl status fwknop-server.service should now show you the service is active Active: active (running). Currently if you have already allowed port 22 with ufw it will stay open until the first time you cycle fwknop with a client.

Client Side:

You have three options fwknop-client, fwknop2 on android - [F-Droid] - [Google play] or fwknop-gui available on Windows, Mac and Linux

In fwknop2 and fwknop-gui:

• KEY_BASE64 -> Rijndael Key
• Key Is Base 64 - Checkbox below key entry
• HMAC_KEY_BASE64 -> HMAC Key
• HMAC Is Base 64 - Checkbox below key entry
• Allow IP - This can be anything as we are ignoring this setting
• Access Ports: tcp/22

The Firewall timeout is in seconds and can be anything as long as it's long enough for you to authenticate. Remember if you have the same set-up as I do, you wont get kicked after the timeout.

And there we go a nice locked ssh port. You will now have to send a SLA to your server prior to connecting with your ssh client.

Having a small home server I've always wanted to encrypt my files, however I have never wanted to be locked out if I'm far away. Enter dropbear ssh. A small light weight ssh server already packaged in debian to work prior to decryption.

Install

sudo apt update && sudo apt install dropbear-initramfs

Note: initramfs will kick up an error after installing dropbear-initramfs. This is solved after adding your public key

Add your ssh key

ssh-keygen -t rsa -b 4096 -o -a 100 -f ~/.ssh/dropbear.id_rsa
sudo cat ~/.ssh/dropbear.id_rsa.pub > /etc/dropbear-initramfs/authorized_keys

Changing the port

/etc/dropbear-initramfs/config

DROPBEAR_OPTIONS="-p 3000"

A little extra security

You can further secure dropbear by disabling forwarding and limiting it to only executing the cryptroot-unlock command.

Just add no-port-forwarding,no-agent-forwarding,no-X11-forwarding,command="/bin/cryptroot-unlock" to the authorized_keys file in front of the ssh public key

It should look something like this:

no-port-forwarding,no-agent-forwarding,no-X11-forwarding,command="/bin/cryptroot-unlock" ssh-rsa A AQQQQQJJQQHx[...]

Finishing up

sudo update-initramfs -u

See the dropbear manpage for further details

Out of the box keepass recognizes the URI ssh:// and will open it with putty. However it is limited, you can't change ports from the default port 22 nor can you save a convenient list of port forwards. Thankfully this is something you can change.

Things you will need:

1. Keepass
2. Putty
3. Keeagent

Alternativly you can do an easy install with the windows package manager chocolatey

choco install putty.install keepass.install keepass-plugin-keeagent -y

URL overrides

We will now define a new ssh:// override globaly in keepass. It is possible to also do so per entry, for portability, however I do not use this feature as I run linux at home and use a separate override on that system.

1. Tools -> Options
2. Integration tab
3. URL Overrides

1. Click the add button
2. Enter ssh in the Scheme field
3. Enter: cmd://putty {T-REPLACE-RX:/{S:Forwards}/\{S:Forwards\}/ /} -P {T-REPLACE-RX:/{BASE:PORT}/-1/22 /} {BASE:HOST} -l {USERNAME} in the url override field. Note: add -pw {PASSWORD} to the end if you wish to auto submit your password. Just be aware this could be considered slightly insecure.

The Keepass entry

1. Create an entry as you normally would adding the ssh:// URL

Note: to add a port just use ssh://example.tld:222

1. If you need port forwards add then under the Advanced tab as a String Field entry in the following format: -L 6080:127.0.0.1:6080 -L 444:10.1.1.1:444

Now when you open the url you will have your putty session with port changes and port forwards.

Breaking it down

1. cmd://putty

   Opens putty via a shell command

2. {T-REPLACE-RX:/{S:Forwards}/\{S:Forwards\}/ /}

   If the string field Forwards doesn't exist delete the string {S:Forwards}

3. -P {T-REPLACE-RX:/{BASE:PORT}/-1/22 /}

   The {BASE:PORT} placeholder returns -1 If a port is not defined. If this happens we should replace it with the default ssh port 22

4. {BASE:HOST}

   The Hostname/IP address part of the URL

5. -l {USERNAME} -pw {PASSWORD}

   Login with the username and (optionally) password of the entry