A Technical I.T./DevOps Blog
Problem scenario
Your NIC on your Fedora Linux server totally will not work. The physical NIC has no lights on it. It seems it is disabled. You cannot enable it with commands.
You see errors like these in logs: “NetworkManager.service: Start request repeated too quickly.”
What should you do?
Solution
Run this command:
journalctl -u NetworkManager
Do you see lines like these?
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Continue reading “How Do You Get a NIC on a Linux Server to Work?”
Problem scenario
You work out regularly at a fitness gym. Is exercise the same as training?
Answer
Exercise is physical activity. Training involves a long-term goal designed to achieve results that will include regular physical activity. Training would include progressively more weights for specific lifts and/or cardio that is increasingly intense or longer in duration.
Source: Starting Strength page 292.
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Problem scenario
A NIC or network interface is not being protected by a zone in the firewalld. You run firewall-cmd commands, and later run “firewall-cmd –runtime-to-permanent” afterward. But a NIC (e.g., a virtual NIC) will not persistently remain in a zone. You want your firewall-cmd commands to have a permanent effect. The “firewall-cmd –runtime-to-permanent” command is supposed to work, but it is not helping. What should you do?
Solution
Run the individual firewall-cmd commands with the “–perm” flag.
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Continue reading “How Do You Get a NIC to Permanently Be in a firewalld Zone with a Single Command?”
Problem scenario
A NIC or network interface is not being protected by a zone in the firewalld. You run firewall-cmd commands with different flags, but some NIC (e.g., a virtual NIC) will not persistently remain in a zone. You want your firewall-cmd commands to have a permanent effect. The –permanent flag is supposed to work, but it is not helping. What should you do?
Solution
If a firewall-cmd command fails with a –permanent flag,
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Problem scenario
You want to not broadcast your home’s network (e.g., to make sure people do not borrow your bandwidth or hack your devices such as your thermostat with ransomware). You want to keep using your WiFi. You try to disable the “Broadcast Network Name (SSID)”, but you get a prompt like “WARNING:
Disabling Broadcast Network Name (SSID) will disable Wi-Fi Protected Setup (WPS) functionality. Are you sure you want to change?”
Should you click “OK”?
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Continue reading “Should You Disable WPS on Your WiFi/Router at Home?”
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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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; …
Continue reading “How Do You Write a Python Program to Extract Lines of a Specific Date?”
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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Question
What is geth in the context of cryptocurrency?
Answer
Geth (go-ethereum) is a Go implementation of Ethereum – a gateway into the decentralized web.
https://geth.ethereum.org/ …
Question
In the context of cryptocurrency, what is Bor?
Solution
It is the way to use MATIC with the Go programming language.
Bor is the Official Golang implementation of the Matic protocol. It is a fork of Go Ethereum – https://github.com/ethereum/go-ethereum and EVM compatible.
https://github.com/maticnetwork/bor …