To patch and protect a Linux server against the Glibc GHOST vulnerability (CVE-2015-0235), you need to upgrade the glibc package to a version later than 2.18. The exact steps for upgrading glibc may vary depending on your Linux distribution and the package management system used. Here are the steps for some of the most common Linux distributions:
Debian and Ubuntu:
sudo apt-get update
sudo apt-get upgrade libc6
RHEL and CentOS:
sudo yum update glibc
Fedora:
sudo dnf update glibc
Note that after upgrading the glibc package, it is recommended to reboot the system to ensure all running processes are using the updated library.
It is also important to keep your Linux server up to date with the latest security patches and updates to ensure that vulnerabilities like GHOST are fixed in a timely manner. Regularly checking for updates and applying them as necessary is an important part of securing a Linux server.