Differences and precautions in building web servers on CentOS 6 and CentOS 7

When you encounter a problem with slow network connection, traceroute can help you locate the bottleneck. It is a command line tool that displays the path through which the data packets pass from your computer to the target server by sending probe packets and recording the response time of each step. How to use it is tracertexample.com under Windows and tracerouteexample.com under macOS/Linux/Unix. In the output result, each line represents an intermediate node, including the number of hops, three round trip times and the corresponding IP or host name; if all hops are *, it may be firewall blocking or network failure. Check the jump with delay burst to determine the location of the problem; combined with multiple domain name tests, you can distinguish between general

The method of changing the system hostname varies from operating system to operating system, but the overall process is simple and clear. First, check the current host name, which can be viewed through the hostname or hostnamectl command; second, the hostname can be temporarily changed, Linux uses sudohostnamenew-hostname, and macOS uses sudoscutil-setHostNamenew-hostname; if you need to change it permanently, Linux needs to edit the /etc/hostname file and update the old hostname in /etc/hosts to the new name, and then run sudohostname-F/etc/hostname or restart to apply the changes; macO

To troubleshoot VLAN problems, you should first confirm whether the configuration is correct, and then check the interface status, cross-device communication path, and STP and ACL impacts in turn. 1. Use showvlanbrief to confirm whether the VLAN exists and the port is correct, and whether the Trunk port allows the corresponding VLAN to pass; 2. Use showinterfacesstatus and showrunning-configinterface to check whether the interface status is up and mode configuration; 3. Verify whether the connection between switches is Trunk and allows the same VLAN, and whether the configuration of the subinterface of the layer three device is accurate; 4. Check whether the STP status of the port is blocked, and check whether the ACL or private VLAN limits traffic. Click this logic

CentOS or RHEL systems recommend using yum and dnf management software packages. 1. It is recommended to update the cache first during installation, the commands are sudoyumininstall and sudodnfinstall respectively; 2. You can update yumupdate or dnfupgrade, and you can view the list to be updated; 3. Use yumremove or dnfremove to delete, and dnf can automatically clean up useless dependencies; 4. Query to view the installation status through rpm-qa and rpm-q, and yuminfo/dnfinfo get detailed information. Mastering these operations can help to efficiently maintain the system.

When encountering an encrypted file, you must first identify the encryption type and then use the corresponding tool to decrypt it. 1. Confirm the encryption method, such as GPG or OpenSSL encryption, through file extension or file command; 2. To decrypt GPG files with gpg command, you need to enter a password or private key such as gpg-ooutput_file-dencrypted_file.gpg; 3. OpenSSL decryption requires specifying algorithm mode such as opensslaes-256-cbc-d-inencrypted_file.enc-outdecrypted_file; 4. File system encryption, such as eCryptfs, automatically decrypts the compressed package after logging in, you can enter the password to decompress.

To troubleshoot Kubernetes node problems, follow the steps: 1. Use kubectlgetnodes and describenode to view the node status and detailed information, and pay attention to the exceptions in Conditions; 2. Log in to the node to check whether the kubelet status, logs and container runtime are normal; 3. Check the network connection and firewall settings to ensure that the port communication with APIServer is normal; 4. Check the CNI plug-in status and related logs. Through the above methods, the cause of the problem can be basically located, and the problem can be effectively solved by checking it in order.

Puppet is an automated configuration management tool suitable for batch management of server environments. First, use the official warehouse to install PuppetServer and Agent to ensure network communication and time synchronization; second, write a list in site.pp to define node configurations, such as installing and starting Nginx; then improve the maintainability and reusability of the configuration by creating modules; finally, use Hiera to achieve configuration data separation, and support multi-environment deployment.

Tocompileakernelmodule,firstinstallbuildtoolsandheadersspecifictoyourdistribution.OnDebian-basedsystems,runsudoaptupdateandsudoaptinstallbuild-essentiallinux-headers-$(uname-r);onRedHat-basedsystems,usesudodnfgroupinstall"DevelopmentTools"a