How to monitor network traffic in real-time on Linux? (iftop and nload)

dnfinstall prompts packagenotfound because it queries the enabled warehouse rather than the local installation status; rpm-q queries the local RPM database, and the scopes of the two are different.

The main reason why Windows cannot see the Samba share is that the firewall blocks UDP137–139/TCP445 or NetBIOS name resolution fails; it is necessary to confirm that the workgroup is consistent, the interfaces are configured correctly, the file permissions match forceuser/forcegroup, and set doscharset=UTF-8 to solve Chinese garbled characters.

The total top CPU usage is not 100% because it is calculated based on a single core, and the maximum is 800% for an 8-core system; the htop terminal size error needs to be fixed with eval$(resize); the real memory pressure is available rather than used; top command line truncation can be solved with the -c parameter.

Logical volumes and file systems can be expanded online. You need to expand the LV first and then the file system. It is recommended to use lvextend-r for automatic synchronization adjustment, but you must ensure that the LVM and file system tool versions are compatible.

Netstat displays fewer LISTEN ports than ss because it does not display process information by default that non-root users do not have access to; ss can read all listening sockets by default without process names, and sudonetstat-tulpn is required to display them completely.

It is recommended to use ssh-keygen-ted25519 to generate a key pair, because it is faster, more secure, and has a shorter key than the default RSA; it is necessary to strictly set the ~/.ssh directory permissions to 700 and authorized_keys to 600, and use ssh-v to confirm whether the client is Offering public key and whether the server rejects it.

When fdisk is stuck at the Command prompt, it is normally waiting for input. Enter q to exit safely; you must umount before mkfs, otherwise it may fail silently; partedmkpart does not support the specified file system type, and mkfs needs to be executed separately.

Netplan reports "InvalidYAML" when configuring a static IP due to indentation errors, missing spaces after colons, or mixed tabs; gateway4 has been deprecated and routes to:default must be used instead; NetworkManager needs to be modified before down/up takes effect; the renderer field is used to determine the backend during coexistence; incorrect DNS configuration will cause ping to succeed but curl to fail.