The guide takes you step‑by‑step through installing a legacy Telnet client on CentOS 9 Stream, stressing that root or sudo privileges are required and that the network must be reachable before you start. It shows how to confirm that both AppStream and BaseOS repositories are enabled, then simply pulls the telnet package with dnf from the standard repository. A quick test against time.nist.gov on port 13 verifies that the client works, while the article supplies troubleshooting advice—such as reinstalling missing plugins or checking firewall rules—if you encounter a “telnet: command not found” error or connectivity problems. Finally, it covers installing a Telnet server with telnet-server and xinetd, but reminds readers that the protocol is unencrypted and should never be exposed to the open Internet.

How to Install Telnet on CentOS 9 Stream

If you’re looking to drop into a legacy service or just want to test your network connectivity, the old‑school telnet client can still be handy on CentOS 9 Stream. This guide walks you through the quick install and how to get it working in minutes.

Prerequisites: Root or Sudo

You’ll need root privileges (or a user with sudo access) because we’re installing packages from the system repositories. If you’re stuck in a minimal environment, make sure your network is up first—no point adding telnet if you can’t reach any servers.

sudo -i          # or use sudo with each command

Step 1: Verify Your Repositories

CentOS 9 Stream ships with the “AppStream” and “BaseOS” repositories by default, but if you’re on a stripped‑down install it might be missing. Check that they’re enabled:

dnf repolist all | grep -E 'appstream|baseos'

If either is marked `disabled`, enable them:

sudo dnf config-manager --set-enabled appstream baseos

Why? The telnet package lives in the BaseOS repo, so we need it to be reachable.

Step 2: Install Telnet

Now that the repos are in place, just pull the client from the standard repository:

sudo dnf install -y telnet

DNF will resolve dependencies and fetch `telnet` along with any necessary libraries. If you get a “No matching Packages found” error, double‑check that your BaseOS repo is enabled—this is the most common hiccup I’ve seen on freshly minted CentOS boxes.

Step 3: Test It Works

Telnet is a simple line‑based protocol, so a quick sanity check is to connect to an open port on a public server. Try reaching `time.nist.gov` on its default port (13):

telnet time.nist.gov 13

You should see something like:

Trying 130.127.5.1...
Connected to time.nist.gov.
Escape character is '^]'.
55420 2026-02-08 10:37:15 UTC
Connection closed by foreign host.

If you get “telnet: command not found,” the install didn’t actually happen—check `/usr/bin/telnet` or reinstall.

Troubleshooting Common Issues

Scenario I’ve seen: After a quick package upgrade on a minimal CentOS image, running `telnet` returns an error because the `dnf-plugins-core` package is missing. That plugin gives us the handy `config-manager` command used above. Fix it with:

sudo dnf install -y dnf-plugins-core

“Telnet fails to connect”

If you can’t reach a target, make sure your firewall allows outbound TCP traffic on the port you’re targeting. A quick test is to use `nc` (netcat) or `curl` first; if those work but telnet doesn’t, the issue is likely with how the server expects the client handshake.

Optional: Install a Telnet Server

If you need a host to listen for incoming telnet sessions (rarely useful today), CentOS ships it in the `telnet-server` package. It runs under `inetd` or `xinetd`. Install and enable:

sudo dnf install -y telnet-server
sudo systemctl enable --now xinetd   # start the super‑daemon

Add a service entry for telnet in `/etc/xinetd.d/telnet` (or use the default). Remember, telnet transmits data unencrypted—don’t expose it to the open Internet.

That’s all there is to it. Drop into your terminal, run those commands, and you’ll have a working telnet client on CentOS 9 Stream in less time than it takes to brew coffee.