About DeRIK What is a Zettelkasten? Latest Posts Archives Search Feed

Zettel 202109140245: Setting Up a TFTP Server for RHEL/CentOS7/8/Fedora

To set up a tftp server in RHEL/CentOS7/8/Fedora, do the following:

# dnf install tftp-server
Last metadata expiration check: 0:13:11 ago on Tue 14 Sep 2021 08:31:55 PM CDT.
Dependencies resolved.
======================================================================================================================================================================================================
 Package                                           Architecture                                 Version                                            Repository                                    Size
======================================================================================================================================================================================================
Installing:
 tftp-server                                       x86_64                                       5.2-32.fc34                                        fedora                                        40 k

Transaction Summary
======================================================================================================================================================================================================
Install  1 Package

Total download size: 40 k
Installed size: 64 k
Is this ok [y/N]: y
Downloading Packages:
tftp-server-5.2-32.fc34.x86_64.rpm                                                                                                                                     73 kB/s |  40 kB     00:00    
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                                                                                  26 kB/s |  40 kB     00:01     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                                                                                                              1/1 
  Installing       : tftp-server-5.2-32.fc34.x86_64                                                                                                                                               1/1 
  Running scriptlet: tftp-server-5.2-32.fc34.x86_64                                                                                                                                               1/1 
  Verifying        : tftp-server-5.2-32.fc34.x86_64                                                                                                                                               1/1 

Installed:
  tftp-server-5.2-32.fc34.x86_64                                                                                                                                                                      

Complete!

Next, start and enable the service:


# systemctl --now enable tftp.service
Created symlink /etc/systemd/system/sockets.target.wants/tftp.socket → /usr/lib/systemd/system/tftp.socket.
# systemctl status tftp.service
● tftp.service - Tftp Server
     Loaded: loaded (/usr/lib/systemd/system/tftp.service; indirect; vendor preset: disabled)
     Active: active (running) since Tue 2021-09-14 20:52:48 CDT; 8s ago
TriggeredBy: ● tftp.socket
       Docs: man:in.tftpd
   Main PID: 2893775 (in.tftpd)
      Tasks: 1 (limit: 4525)
     Memory: 188.0K
        CPU: 3ms
     CGroup: /system.slice/tftp.service
             └─2893775 /usr/sbin/in.tftpd -s /var/lib/tftpboot

Sep 14 20:52:48 localhost systemd[1]: Started Tftp Server.

I get stumped by the fact that you install tftp-server but you start tftp.service. I’d like some consistency with the naming, here. Oh well . . .

Notice your default home directory is /var/lib/tftpboot. Place the files that you want to serve with tftp in that directory.

If you’re running firewalld, you’ll need to allow the service:

# firewall-cmd --zone=public --add-service=tftp --permanent

success

All done. If you’re still having problems after these steps, check for the following:

  • Did you forget to install tftp on the client device?
  • Is a firewall running on the client device?
  • Is a network firewall or router preventing the server and client from talking over port 69 UDP?
  • Remember, TCPDUMP is your friend.

September 14, 2021 unlinked cli

Zettel 202109141140 : Helpful mv Command Options

The b flag creates a backup of the destination file.

The mv command creates a backup in the destination directory. This protects against overwrites.

$ ls
somefile.txt

$ mv -b somefile.txt /home/destination

$ ls /home/destination 
somefile.txt somefile.txt~

The file with the tilde (~) character is the backup. That is a copy of the file that the mv command would have overwritten.

Another helpful option is the u flag.

The update or u flag only overwrites a file if the source is newer than the destination file. This flag also has the i or interactive option built into it.

September 14, 2021 unlinked cli

Zettel 202109122305 : Passwordless SSH Key setup for RedHat/CentOS

Running these commands will set up passwordless SSH between two servers. You do this by generating a public and private key pair. Then, you share the public key with the server with which you want to connect.

First, create your key pair:

$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/$username/.ssh/id_rsa): 
Created directory '/home/$user/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again: 
Your identification has been saved in /home/$user/.ssh/id_rsa
Your public key has been saved in /home/$user/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:QO+nBQ/I01h9an9TuWVed0eKlL4rLAXQDu+pDsUK1sk $user@localhost
The key's randomart image is:
+---[RSA 3072]----+
|      ....   .   |
|     oo*. . +   .|
|      *==  = . o.|
|   o o +++o o ..O|
|  o E o.S++. . +B|
| . . o  o+. o o..|
|    o  ..o   o . |
|     .. . o .    |
|     ..  . .     |
+----[SHA256]-----+

If you enter a passphrase, you won’t have a passwordless key. So, press Enter without adding a passphrase for your key.

Next, send your new key to the server with which you want to connect:

$ ssh-copy-id -i ./ssh/id_rsa.pub $user@remote-server
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: 
"/home/$user/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), 
to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- 
if you are prompted now it is to install the new keys
$user@remote-server password:
Number of key(s) added: 1

You’ll need to enter your password this one time. After that, ssh-copy-id will send your public key over to the remote server.

This implies that the same user should already exist on the remote-server.

Finally, enjoy your Passwordless SSH key.

The next time you connect via SSH, you won’t need to submit your password.

September 13, 2021 unlinked cli

Zettel 202109121353 : Your routines are a law of Nature like gravity, entropy, or the speed of light

Like the laws of Nature, you cannot escape your habits and routines. To have a different result in life, you must develop different habits and routines.

You do not rise to the level of your goals. You fall to the level of your systems.

James Clear, Atomic Habits

Clear says on his Twitter feed that he adapted this saying from the Greek poet Archilochus:

We don’t rise to the level of our expectations, we fall to the level of our training.

At first I understood this to mean you must focus on the process that achieves your goal, not the goal itself. Otherwise, you won’t reach or maintain your goal once it stops motivating you. Getting close to or reaching your goal can cause you to lose motivation. That’s why you must focus on the routines that help you reach your goal. Keep the routine that generates the results. You need to make that the goal. Don’t make your desired results the goal.

But lately, I’ve spent time learning more about cosmology, entropy, and Information Theory. And I finally see something else from Clear’s quote. Your habits, routine, training, and systems are themselves a law of Nature. Laws of Nature allow and forbid certain outcomes. Routines and habits over time do the same thing.

Airplanes don’t defy gravity. They work within the limits and allowances of gravity. And they work in the limits and allowances of all the other physical forces, too. The Wright brothers show this by modifying their plane after each failed attempt. And finally, they achieve flight. And others have improved on the prototype ever since.

In that same way, you don’t improve by defying the results of your bad habits. You don’t conjure desired results from a broken routine. Instead, you adopt better habits bring the desired results to you. Your routines and habits set the limits and allowances of your possible outcomes. Like the laws of Nature, your routines will decide what you can achieve and have.

What new habits and routines can I work on? What routines have I let slip that worked well for me in the past? What do I need to remove from my life so that I have time for the important routines?

Here are some routines I that I know improve my life:

  • Strength Training
  • Monitoring my calory intake
  • Cardio
  • Cooking at home instead of eating take out
  • Preparing meals ahead of time
  • Tidying up in small, frequent bursts throughout the day
  • Keeping my laundry load small by washing often
  • Putting laundry away as soon as I take the clothes out of the dryer

I noticed I let these routines slip when I had to report back to the office. Now I see, I need to adapt so that I can re-establish these routines. They’re too important to abandon.

Here are some goals I have. And I need to establish routines for them:

  • Improving my work skills on a regular basis
  • Learn new things that I’m interested in
  • Show more attention to the loved ones and friends in my life
  • Improve my attractiveness to my current employer and to prospective ones, too
  • Understanding money management

What should I remove from my life to make more time for the important routines?

I already avoid watching television and spending time on social media. I don’t have much to cut there. I need a more flexible job. I may need to seek out services that can help me save time.

I’ll revisit this topic over time. Routines are essential to self-improvement.

Here’s a cosmology reference that influenced my thinking: [Zettel 202109062200]. This is only one science reference that influenced this idea. I’ll link the other Zettels here as I write them. The ideas are in my head, but not in my notes just yet.

September 12, 2021

Zettel 202109072304: I need a Go Bag and Stay Bin.

Climate change is driving the need for emergency preparedness. I thought about packing a go bag for a few years now. And I also thought about preparing for a long, trapped stay at home. The kind of stay with no power, running water, or emergency help. Enter: the go bag and stay bin.

The Go Bag

  • Emergency whistles (Yay! I already have some of these!)
  • Water
  • Snacks
  • Important documents like birth certificates, passports, and social security cards. I should place them in a waterproof bag.
  • Pet records
  • Pet supplies like food, extra leash, and harness. A portable water bowl
  • Extra phone chargers and emergency chargers
  • batteries
  • flashlight
  • A list with phone numbers from close family members or anyone else I need to contact. This list is for me and for someone who may need to contact someone on my behalf.
  • Extra pair glasses or contacts if possible.
  • Cash (small bills if possible)
  • First aid kit
  • Masks (regardless of a pandemic)
  • Extra medication
  • Extra car keys
  • A map
  • A compass
  • A survival field manual

Of course, some of these items may take time to collect. But, I can always get started with the simple items that I already have.

I should also consider starting individual go bags for each family member. That helps them have the unique items that they each need.

The Stay Bin

  • All the items from your Go Bag plus . . .
  • Extra blankets
  • Firewood
  • Solar cell phone charger
  • Candles
  • Matches
  • Headlamp
  • Two weeks supply of non-perishable food
  • Two weeks supply of non-perishable pet food
  • Two weeks supply of water for everyone in your household (plus pets)
  • A hand-crank weather radio
  • An uninterruptable power supply
  • Extra toiletries (toilet paper, toothpaste, toothbrushes
  • Trash bags
  • Hand wipes
  • Hand sanitizer
  • Duct Tape
  • Multi-purpose tools

Place these items in several large bins. That way, you won’t use them until the time they’re needed. And you’ll also have it all in one place.

Bonus: Crisis Notebook

I should also create a document that tells the family what to do if I become incapacitated. And of course, I need to make sure they can find it. I guess I can throw that in the go bag.

References:

Parker-Pope, T. (2021, September 2), Is Your ‘Go Bag’ Ready? The New York Times. https://www.nytimes.com/2021/09/02/well/go-bag-essentials.html?smid=url-share

Ready.gov

A special thanks to Pocket for recommending the NY Times article.

September 7, 2021 projects preparation preparedness

Zettel 202109032239: Is a giant Zettelkasten hiding within the Internet?

I used a search engine to learn more about the structure of a Zettelkasten.

My search term was:

zettelkasten ledger

The second result caught my eye:

Money - My Zettelkasten

https://sudeepdino008.github.io › zettelkastenFiat currencies have their stability issues. Either weak monetary policy (lost of currencies issues) or weak fiscal policy. Ledger can either be transaction or …

Interesting!

So, I clicked the link. And got:

GoHome

As far as 404 errors go, that was also interesting.

So, I explored the blog further.

And I finally came to the author’s musings on asking questions. And I noticed the author had posted notes on a book they’re reading.

And this inspired me to reevaluate how I’m writing my own notes for my Zettelkasten. And, now the author’s musings impact my own.

Your own Zettelkasten will do this in time as it grows.

And I’m especially interested in the musing on asking the right questions. I have found a new book to read.

I wish I could tell the author how I found their blog refreshing. I wish I could tell them “thank you”.

Why?

Because reading their page has created new connections between ideas in my own mind. This is one of the things we look for from a Zettelkasten.

But does that mean a giant Zettelkasten is hiding within the Internet?

The Internet shares a few similarities with a Zettelkasten. The content on the Internet creates a web of connections. Zettels will also create a similar web-like connection over time. As I showed above, other Internet sites can inspire new ideas. A Zettelkasten does this, too. And they both do this because they create something bigger than the sum of their parts.

But I do see a key difference between the Internet and a Zettelkasten. The Internet is a group of sites created by other entities. But a Zettelkasten is a collection of your own notes and ideas linked together. Yes, you may write notes on other people’s ideas too. But now you’re thinking about those ideas. And now you want to explore and expound on them. You’re looking for a way to import these ideas into your own thinking.

So, the Internet doesn’t have a giant Zettelkasten hiding within it. But you can find people like me putting their Zettelkastens on it.

September 3, 2021