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Configuring Network on RHEL 8


1. Validate Network Configuration


2. Configure Network

Networking is managed by a service called NetworkManager. It reads the network card configuration scripts located at /etc/sysconfig/network-scripts.  Each network card can have one or many connections.

The commands to configure network are nmtui and nmcli. Another way is a GUI tool called nm-connection-editor.

nmtui is text based UI with limited options.

nmcli has rich features and you don't need to memorize. Here are nice ways to check it out.
  • man -1 nm-settings  : to check user command
  • man -5 nm-settings  : to check file formats and conventions
  • man nmcil-examples : to find examples
Example:
  • nmcli con show|add|mod|up...
  • nmcli dev show...
3. Set up Hostname and Name Resolution

To view or change the hostname, a few options are:
  • Use nmtui
  • Use hostnamectl
    • hostnamectl status
    • hostnamectl set-hostname
  • Edit /etc/hostname
To set hostname resolution, you can use DNS and edit /etc/hosts.

The definitions in /etc/hosts will be applied before the hostname in DNS is used.

Tips: /etc/hosts contains the local host and DNS servers.
/etc/hostname contains only the local server.

To communicate with the internet, you should set up the DNS. Here are a few options to set up the DNS:
  • Use nmtui
  • Use nmcli to find the static network card, do either of
    • modify the parameters: DNS1 DNS2
    • modify the option: ipv4.dns <ip-of-dns>
  • Use a DHCP server
The configuration written here will show up in /etc/sysconfig/netowrk-scripts. NetworkManager service will pick this up and push it into /etc/resolv.conf.

After all, you can verify it's configured correctly by:
  • getent hosts <servername>
It checks in both DNS and /etc/hosts to resolve the hostname.

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