Architecting teamtask / list: The early years

Teamtask (a.k.a. List) is a pet project / algorithm I developed back in 2000 as part of a brute force password cracking experiment.  Actually though, now that I think about it, I originally started working on the algorithm in 5th grade.

Back in my early years I wanted to password protect my computer, which wasn’t a thing back then.  I set about writing a program with a prompt for a username and password.  It worked.  I could start it up when the computer started, and though you could just ctrl-c out of it (not super sophisticated), my next thought was how could someone get around it.  I began investigating how to generate all passwords so they all could be tested one after another until the password was guessed.  I figured out the following two algorithms given a string of 3 characters ‘abc’ and length ‘3’:

aaa 111 000
aab 112 001
aac 113 002

abc 123
acb 132
bac 213
bca 231
cab 312
cba 321

The algorithms were thus: one generating all combinations with reusing characters and one without reusing characters.  The first worked best for brute force password cracking (though I didn’t know the term at the time, if it even existed).  But, in 5th grade I wasn’t able to create the algorithm to generate the strings.  Later in life though, I was able to create an algorithm for both using iteration with a base equal to the number of characters, rather than base 10, along with factorials(!).

With these two algorithms the following became possible:  If there were 6 possible arrangement of characters I could give a client the number, such as 1 along with a string of characters ‘abc’ and the client could translate that into ‘abc’, and do something with it (test if the password works).  Since the client only needed the index, and the string of characters, we could also give out a block of characters such as index=0, size=3.  This would result in two blocks that two different clients could work on simultaneously.  Each client would take a block, process three combinations, then report back the result.

Implementing the algorithm there’s one more magic that occurs.  One might initially implement the algorithm above in the following way, given 100 items to complete, and breaking those into chucks of 10, you could add 10 records to a database to reflect these blocks pending completion:

index = 0, size = 10, status = pending
index = 10, size = 10, status = pending

index = 90, size = 10, status = pending

After each completes you could mark the status as ‘completed’ and once all blocks are completed flag the Job as done.

However, this would mean when processing more extreme lists with thousands of blocks, think testing for the largest prime number ever found, you wouldn’t want to hold the status of all blocks.  With one more algorithm this concern disappears, what you do is merge sibling blocks, so if you have three blocks in a row and clients are working on them: (0, 10, 0), (10, 10, 0), (20, 10, 0), and the second two complete (0, 10, 0), (10, 10, 1), (20, 10, 1) , you can merge them for tracking purposes: (0, 10, 0), (10, 20, 1), and if the first completes you can merge again, (0, 30, 1), indicating from position 0 of size 30, all of those have been completed.  This conveniently means that when the whole list has been processed you will have one block with the whole size in completed status (0, 100000000, 1).

The algorithm has evolved to have timeouts with blocks, to handle the use case of a client disappearing while working on a block (or crashes), limiting the number of blocks a client can have at one time (to avoid some level of someone trying to interfer with processing by requesting blocks and not working on them), and work with OIDC to work within an enterprise infrastructure.

Roadmap:
– implement teamtask (a.k.a. list) as a container
– implement webapp gui & mobile gui, both with single implementation using flutter

Using kubeadm to setup cluster using centos 9 stream.

Is centos 9 stream a good choice? (sure)

I may end up switching to Sidero to setup and manage my onprem clusters, but for now I am continuing with centos, and moving from 8 to 9 so that I can use the wireguard module that comes with 9.  After several failures I have tracked down the few steps different from a centos 8 stream install.  Hopefully this will save someone a lot of days (and days and days, weeks?) of troubleshooting.

The key differences are:

1. In centos 8 stream you only needed to change the containerd from disabling containerd.  In centos 9 stream you need to copy the whole default configuration and change it to use systemd cgroup.  This script is currently working for me:

# make a copy of the default containerd configuration
containerd config default | sudo tee /etc/containerd/config.toml
# set to use systemd
sed -i 's/SystemdCgroup = false/SystemdCgroup = true/g' /etc/containerd/config.toml
# adjust pause image to what's actually installed
PAUSE_IMAGE=$(kubeadm config images list | grep pause)
sudo -E sed -i "s,sandbox_image = .*,sandbox_image = \"$PAUSE_IMAGE\",g" /etc/containerd/config.toml

# restart the containerd service
sudo systemctl enable containerd
sudo systemctl restart container

2. There is something odd happening when performing the ‘kubeadm init’ which I was able to get around by doing the following:

# avoid a couple phases when performing kubeadmin init
sudo kubeadm init --control-plane-endpoint="<put_endpoint_here>:6443" --upload-certs --pod-network-cidr=<put_cni_cidr_here> \
--skip-phases=addon/kube-proxy \
--skip-phases=addon/coredns

# wait about 40 seconds then run the following to run the previously skipped phases
sudo kubeadm init phase addon all \
--control-plane-endpoint="<put_endpoint_here>:6443" \
--pod-network-cidr=<put_cni_cidr_here>

If I get a chance I’ll put together a video for this since there doesn’t seem to be one out there in the wild yet.

tether laptop via android phone in such a way as to give the laptop access to the phone’s vpn

Android tether how to:

  1. Setup wireguard on your phone to your network, this allows you to access your hosted webapps, and your laptop will also get to have access
  2. On phone install sshd such as simplesshd, by default it uses port 2222
  3. On laptop install adb, plug phone into usb, then run “adb forward tcp:2222 tcp:2222”, this will forward localhost:2222 on your laptop to the sshd running on the attached phone
  4. On laptop connect to ssh server using putty @ localhost on port 2222, also setup a port forwarding tunnel such as ‘Source port = 9999’, select ‘Dynamic’, nothing for destination
  5. This sets up a socks proxy, now on the laptop run chrome pointing it at the socks proxy c:\…\chrome.exe –proxy-server=”socks5://localhost:9999″ (easiest to just edit the shortcut).  ** before launching chrome in this way you have to close all chrome instances, otherwise it will appear not to work

There you go, now on your laptop you’ll be able to reach your home webapps as it will proxy through the phone which is running the vpn.  Note: you’ll also have to enable developer access in order to use adb.

This is perhaps not as secure as just using your phone’s built-in tether options, mine seems to put tethered connections behind a NAT which is a good idea, but in my case I wanted my laptop to use the vpn the phone was using.  Good luck!

Additional, openvpn:

Instead of configuring chrome to use the socks5 proxy, you can setup openvpn to use the socks5 proxy, then all of your networking will work, not just chrome. Just add the following to your openvpn client config (you’ll also need to setup an openvpn server of course, the above setup does not require it to be open to the internet, we access it via the ssh tunnel):

proto tcp
socks-proxy localhost 9999
connect-retry-max 1

remote <openvpn_ip> <openvpn_port> tcp

Actually, maybe the socks5 proxy isn’t needed at all if using openvpn, it just needs its port forwarded, no?

k8s-at-home, another project deprecated while at its prime

The open source community it capable of incredible things all working their main jobs then building things outside of work … but, it is all too common for people to also want to have a life outside of work.

We’ve lost another project just due to a lack of maintainers / availability.  It’s sad when it happens.  Even I didn’t have time to help out, and now it’s gone.

If only there were a way to pay people to maintain open source projects.

Think I’ll have a drink tonight in celebration of the k8s-at-home folks, thanks for everything you did.