diff --git a/books/free-programming-books-subjects.md b/books/free-programming-books-subjects.md
index b4fee21a8..2f09dde2a 100644
--- a/books/free-programming-books-subjects.md
+++ b/books/free-programming-books-subjects.md
@@ -891,6 +891,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [How to deal with Passwords](https://github.com/MHM5000/pass)
 * [Information Security Management](https://www.infosecuritybook.com) - Marcos Sêmola (PDF)
 * [Intrusion Detection Systems with Snort](https://ptgmedia.pearsoncmg.com/images/0131407333/downloads/0131407333.pdf) (PDF)
+* [Network Security](https://www.open.edu/openlearn/digital-computing/network-security/altformat-printable) - OpenLearn (PDF)
 * [OpenSSL Cookbook](https://www.feistyduck.com/library/openssl-cookbook/)
 * [OWASP Mobile Security Testing Guide](https://mobile-security.gitbook.io/mobile-security-testing-guide/) - Bernhard Mueller et al.
 * [OWASP Testing Guide 4.2](https://owasp.org/www-project-web-security-testing-guide/v42/) - The OWASP® Foundation (HTML, [PDF](https://github.com/OWASP/wstg/releases/download/v4.2/wstg-v4.2.pdf))