How Do You Install uffd?

Problem scenario
You want to install uffd on Linux.

Solution
uffd refers to "userfaultfd" that is often available on Linux.

Type "man userfaultfd" to see if it is available.

userfaultfd is a system call (as can be discovered by running "man syscalls" and searching for "userfaultfd").

To read about support for userfaultfd, see https://github.com/rr-debugger/rr/issues/2852.

If you have a modern Linux system without userfaultfd, please let us know (and run "cat /etc/*-release" and provide the results of this command in your response). We would be curious to find out what distribution does not have it.

How Do You Install Firecracker on Ubuntu?

Problem scenario
You want to install Firecracker on Ubuntu. What do you do?

Solution
Run these commands:

release_url="https://github.com/firecracker-microvm/firecracker/releases"
latest=$(basename $(curl -fsSLI -o /dev/null -w %{url_effective} ${release_url}/latest))
arch=`uname -m`
curl -L ${release_url}/download/${latest}/firecracker-${latest}-${arch}.tgz | tar -xz
    
sudo mv release-${latest}-$(uname -m)/firecracker-${latest}-$(uname -m) /usr/local/bin/firecracker
        
sudo setfacl -m u:${USER}:rw /dev/kvm
    
firecracker --version   

What Is The Command to Find What Version of SSH You Are Using?

Problem scenario
You are concerned you have an older, vulnerable version of OpenSSH. What command should you run to see what version you are using?

Solution
ssh -V

Versions from 4.4p1 up to, but not including, 8.5p1 are not vulnerable due to a transformative patch for CVE-2006-5051, which made a previously unsafe function secure.

https://blog.qualys.com/vulnerabilities-threat-research/2024/07/01/regresshion-remote-unauthenticated-code-execution-vulnerability-in-openssh-server

How Do You Swap a Cryptocurrency in Coinbase Wallet when You Get “You need ETH before you can make a transaction on the Ethereum network” as an Error?

Problem scenario
You are using the Coinbase wallet. You try to swap a currency. You click on "Find best price." But you see "You need ETH before you can make a transaction on the Ethereum network."

You do have ETH in your wallet. How do you proceed?

Possible Solution #1
Use the Coinbase Wallet app on a phone instead of the website version. It will provide you with more information on how much ETH you actually need.

Possible Solution #2
Do you have "ETH on Base" or "ETH on Ethereum"? The symbols are as follows:

The top of the above shows ETH on Base. The lower of the above pic shows ETH on the Ethereum network.

If the swap is going to be on the Ethereum network, you need to have ETH on Ethereum -- not Base. Move the ETH to ETH on the Ethereum network.

Possible Solution #3
Add more ETH to your wallet. (Make sure it is on the Ethereum network.)

How Do You Edit a PDF for Free Using Windows?

Problem scenario
You are using Windows, and you want to modify a PDF file without uploading it to a website. What can you do (without paying for an application)?

Possible Solution #1 (e.g., to black out sensitive content)
1. Install Firefox.
2. Open Firefox and then open the PDF in Firefox.
3. Hover over the pencil icon with a squiggly line.
4. Click it and adjust the thickness to your desire.
5. You can edit the document now.
6. Save it with a new name.

How Do You Harden Your Website to Not Show info.php?

Problem scenario
You go to your website's domain, and you find the info.php page displays like this:

www.acme.com/info.php

This is a security concern. You are using WordPress. How do you hide it?

Solution
1. Copy your .htaccess file. Keep a backup.

2. Make a modified copy that is separate.

3. Outside the WordPress section (e.g., after the "# END WordPress" section), enter this (but replace "1.2.3.4" with your own IP address):

Order Deny,Allow Deny from all Allow from 1.2.3.4

4. Save the .htaccess file.

5. Upload the .htaccess file but keep the original unmodified file as a backup.

How Do You Use PowerShell to Correct the Time on Your Windows Machine?

Problem scenario
You are trying to correct the time of your Windows machine. You run "w32tm /resynch", but you get "The following error occurred: The service has not been started. (0x80070426)". What should you do?

Solution

  1. Open PowerShell as administrator.
  2. Run these five commands:
net stop w32time
w32tm /unregister
w32tm /register
net start w32time
w32tm /resync /nowait

If you wanted a non-PowerShell method, see this posting.

Why Does the Declaration of Independence Study Guide say Carter Braxton died in 1761?

Problem scenario
The "brief biographies of the signers" of the laminated guide of The Declaration of Independence (a QuickStudy Academic publication) indicates that Carter Braxton died in 1761. Why is this?

Answer
It is a mistake. He died in 1797 according to https://encyclopediavirginia.org/entries/braxton-carter-1736-1797/

The laminated guide is not bad all-in-all. You can buy it on Amazon.

Why Was The Bridge Considered “rude” in Emerson’s Concord Hymn?

Question
Emerson's famous poem named Concord Hymn begins with: "By the rude bridge that arched the flood,"

Why was the bridge considered "rude"?

Answer
The short answer is the word "rude" means "unfinished" (as opposed to being disrespectful), and the condition of the bridge in the 1830s was poor [6] or possibly non-existent [5].

Here is the longer answer:

This was the poem with the well-known quote "the shot heard round the world." It was originally written to dedicate a monument at the North Bridge [5] in Concord. Understand that it is called "Concord Hymn." A hymn is a short poem to honor the Christian God [4]. This poem combines aspects of the American town of Concord with praise of the Christian deity.

Remember that this poem only has 105 words, and there may have been a recency bias to stimulate the author's thoughts. The poor or absent bridge would have given the author the idea to use the word "rude."

The word "bridge" can be a metaphor too. In this New England poem, despite its short length, the word "bridge" appears twice.

The other line with the word "bridge" says "And Time the ruined bridge has swept." The bridge has now been described as "rude" and "ruined." The author is consistent with adjectives that start with "ru." This conjures the lack of a bridge the American colonies would have to Great Britain [in the War for Independence].

There is a motif of water throughout the poem, and in 1776 the country was not very refined. Geographically the bridge arches over a river. In the poem (or "hymn") the bridge arches a flood. The original Biblical flood, which may have been dear to Christian Americans at the time, could be a way for a poem to summon a beginning of a people (in the poem's case, the American people). The monument itself thanked God explicitly [6].

The first definition of "rude" in Noah Webster's 1828 dictionary (who was originally from New England) is "rough; uneven; rugged; unformed by art; as rude workmanship, that is, roughly finished; rude and unpolished stones." [2] The first definition of "rude" in Merriam-Webster's Collegiate Dictionary 11th edition is "being in a rough or unfinished state."

The poem says "We set today a votive stone…The shaft we raise to them and thee." This is a reference to the dedication of the mostly granite monument [6] that was and still is in the form of an obelisk.

Poets love metaphors and imagery. If a bridge is rude (rough or unfinished), there is room for refinement. The celebration of the Battles of Lexington and Concord were to honor the country (and the towns). A bridge may be a pathway to the future or a way to unite diverse people in different locations. To remember the battle as the beginning of the American people, it may have been Emerson's goal to describe the passageway over the water as unfinished to illustrate the improvement that would come later. Or he was just primed to discuss the dilapidated bridge (or its complete disappearance [7]).

It may be advisable to critique poemanalysis.com that says '[t]he use of the word “rude” in the context is to refer to the bridge’s structure. It was not of complicated construction—it was simple.' [1]
The condition of the bridge in the 1830s was poor according to [5] or non-existent according to [6]. [7] suggests the original bridge was definitely not there.

To read the full poem, see [3].

[1] https://poemanalysis.com/ralph-waldo-emerson/concord-hymn/
[2] https://webstersdictionary1828.com/Home?word=rude
[3] This was taken from https://pressbooks.pub/poetrypoetics/chapter/concord-hymn/:

By the rude bridge that arched the flood,
Their flag to April’s breeze unfurled,
Here once the embattled farmers stood
And fired the shot heard round the world.
The foe long since in silence slept;
Alike the conqueror silent sleeps;
And Time the ruined bridge has swept
Down the dark stream which seaward creeps.
On this green bank, by this soft stream,
We set today a votive stone;
That memory may their deed redeem,
When, like our sires, our sons are gone.
Spirit, that made those heroes dare
To die, and leave their children free,
Bid Time and Nature gently spare
The shaft we raise to them and thee.

[4] https://webstersdictionary1828.com/Home?word=hymn
[5] https://www.nps.gov/places/1836-battle-monument.htm
[6] https://freedomsway.org/place/1836-battle-monument/
[7] https://www.facebook.com/lostnewengland/posts/the-old-north-bridge-in-concord-massachusetts-where-the-shot-heard-round-the-wor/830401999092119/

How Do You Troubleshoot “ZFS modules cannot be auto-loaded” or “FATAL: Module zfs not found in directory”?

One of the two problem scenarios apply.

Problem Scenario #1
You run this: sudo modprobe zfs. You get this:

modprobe: FATAL: Module zfs not found in directory /lib/modules/6.1.0-37-cloud-amd64

Problem Scenario #2
You run this: zpool list

You get this:

The ZFS modules cannot be auto-loaded.
Try running 'modprobe zfs' as root to manually load them.


How do you solve the above problems?

Possible Solution #1
Run sudo zpool list

Possible Solution #2
Run this (but be ready for it to take ~30 minutes or longer to complete):

sudo apt install linux-headers-$(uname -r)