How Do You Troubleshoot an IP Address That You Can SSH to, But You Cannot Ping It?

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Problem scenario
nmap shows that the host seems down. You cannot ping the IP address. But you can SSH to the IP address. How is this possible?

Solution
Possible Solution #1
A host server could have multiple IP addresses (e.g., with a virtual server hosted by a type 2 hypervisor utilizing KVM or QEMU). The networking could be done at the kernel level.

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How Do You Write a Python Program to Extract Lines of a Specific Date?

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Problem scenario:
You have a log like this:

Sep 18 07:28:11 server1 sshd[29284]: Received disconnect from 125.52.17.109 port 46970:11: Bye Bye [preauth]
Sep 18 07:28:11 server1 sshd[29284]: Disconnected from 125.52.17.109 port 46970 [preauth]
Sep 18 07:28:11 server1 sshd[29282]: Failed password for root from 51.12.19.109 port 24844 ssh2
Sep 18 07:28:13 server1 sshd[29287]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=119.29.155.214 user=root
Sep 18 07:28:13 server1 sshd[29282]: Failed password for root from 51.12.19.109 port 24844 ssh2
Sep 18 07:28:14 server1 sshd[29282]: Received disconnect from 51.12.19.109 port 24844:11: [preauth]
Sep 18 07:28:14 server1 sshd[29282]: Disconnected from 51.12.19.109 port 24844 [preauth]
Sep 18 07:28:14 server1 sshd[29282]: PAM 2 more authentication failures; …

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What is MEV?

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Question
What does MEV stand for in the context of cryptocurrency?

Answer
MEV means Maximal Extractable Value; it used to mean “Miner Extractable Value” according to Coindesk.com. Cryptocurrency miners solve problems and receive a reward for doing so.

If a miner is able to successfully add a block to the blockchain, they will receive … bitcoins as a reward.

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What is MATIC in cryptocurrency?

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Question
What is MATIC in the context of cryptocurrency?

MATIC is Polygon’s native cryptocurrency token.
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Before the project changed its name in February 2021, Polygon was known as Matic network.

https://cointelegraph.com/learn/polygon-blockchain-explained-a-beginners-guide-to-matic

MATIC is the currency of Polygon that enables users to interact with tens of thousands of dApps involved in our ecosystem. It is also used to secure the network by staking.

https://polygon.technology/matic-token

Polygon (MATIC) is a cryptocurrency and a technology platform that was launched to connect and grow Ethereum-compatible projects and blockchains.

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How Do You Troubleshoot the Error Message “Client sent an HTTP request to an HTTPS server”?

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Problem scenario
You run curl commands, but you keep getting this error “Client sent an HTTP request to an HTTPS server.” What should you do?

Possible Solution #1
Use https instead of http. See this for more information.

Possible Solution #2
The “problem” is not actually a problem or a true error message.

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How Do You Troubleshoot a “SyntaxError: invalid syntax” Error in Python?

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Problem scenario
You do not know why you are getting the error. The line has an “l” (a lowercase “L”) or a numeral one (“1”) in it.

You may have identified that the line of code is different in one file from another. You cannot tell what is different about your code or why you are getting this error. What should you do?

Solution
Enter vi or open Notepad++ to view the code.

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How Do You Set Up a New Linux Server on Hardware?

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Problem scenario
You are configuring a new physical server without an image, without an automated unattended installation script or a remote ghosting-type tool (such as Ghost or the NIM tool). How should you format it, install Linux and configure it?

Solution

  1. Gather the requirements for what its purpose will be and how the monitoring/maintenance and support will be done.
  2. Configure the BIOS/iLOs/iDRACs first.

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How Do You Troubleshoot This Error: “no limited resources used”?

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Problem scenario
You run quota -g foobar where “foobar” is the name of the group you want a quota to apply to. But you get this: “Disk quotas for group foobar: no limited resources used”

What should you do?

Possible solution
Run a command like this:
sudo quotacheck -gm /path/to/filesystem

(Don’t use the -u flag if you have no user quota configured.)

Now try the quota -g foobar command again.

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