How Do You Get a NIC to Permanently Be in a firewalld Zone with a Single Command?

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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?

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How Do You Get a NIC to Permanently Be in a firewalld Zone with Multiple Commands?

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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 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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Should You Disable WPS on Your WiFi/Router at Home?

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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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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.

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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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