CentOS 7 Server Initialization: Configuring YUM Repositories, Installing Essential Packages, and System Optimizations

1. Configure the YUM repository to use Alibaba Cloud mirrors by moving existing repo files and downloading new CentOS-Base.repo and epel.repo , then refresh the cache with yum makecache .

2. Install a collection of essential tools and libraries using yum install -y libcurl openssl lrzsz httpd gcc cpp binutils glibc-kernheaders glibc-common glibc-devel make gcc-c++ automake autoconf libtool zlib-devel openssl-devel tree nmap sysstat dos2unix telnet bash-completion bash-completion-extras vim nc lsof net-tools rsync ntpdate open-sshclients screen nload wget .

3. Stop and disable the firewall service with systemctl stop firewalld and systemctl disable firewalld .

4. Disable SELinux enforcement by running setenforce 0 and editing /etc/sysconfig/selinux to set SELINUX=disabled .

5. Stop and disable NetworkManager using systemctl stop NetworkManager and systemctl disable NetworkManager .

6. Add a cron job to synchronize the system clock with Alibaba Cloud NTP servers by appending the appropriate ntpdate command to /var/spool/cron/root .

7. Increase the maximum number of open file descriptors by appending * - nofile 65535 to /etc/security/limits.conf .

8. Optimize the command line environment by creating /etc/profile.d/color.sh with colorized ls alias, a customized prompt, and a timestamped history format, then source the profile.

9. Tune kernel and network parameters by backing up /etc/sysctl.conf , writing a series of net.ipv4.* , vm.swappiness , and other kernel settings, and applying them with sysctl -p .

10. Set the hostname temporarily with hostname and permanently with hostnamectl set-hostname .