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Faruk
Faruk

Posted on • Originally published at Medium

The 5 Most Dangerous Linux Services If Left Unsecured | by Faruk Ahmed | May, 2025

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The 5 Most Dangerous Linux Services If Left Unsecured

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✍️ Full Blog Content:

Intro:

Not every service running on your Linux server is dangerous — until it’s exposed. Some are necessary, others are legacy, and a few are downright risky if left open to the public. In this post, I’ll walk you through the top 5 Linux services I’ve seen most often exploited in real-world attacks, and what I do to lock them down.

1. SSH (Port 22)

✅ Why it’s dangerous:

  • Most-scanned port on the internet
  • Brute-force targets
  • Common misconfigurations (e.g., root login enabled)

✅ What I do:

  • Move to port 2210
  • Disable root login
  • Use key-based auth only
  • Set MaxAuthTries 3 in /etc/ssh/sshd_config
  • Protect with fail2ban

2. FTP (Ports 20, 21)

✅ Why it’s dangerous:

  • Sends credentials in plain text
  • Still found in old web hosting setups

✅ What I do:

  • Replace with SFTP
  • If absolutely needed, use vsftpd with encryption only

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