# Lab: Protect IS-IS Routing Data with MD5 Authentication

DevFeed: [Lab: Protect IS-IS Routing Data with MD5 Authentication](<https://devfeed.tech/articles/lab-protect-is-is-routing-data-with-md5-authentication-11239.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/09/isis-lab-authenticate/>)

Published: 2025-09-26T05:40:00Z

Content type: tutorial

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [IS-IS](<https://devfeed.tech/topics/is-is.md>), [networking](<https://devfeed.tech/topics/networking.md>), [Authentication](<https://devfeed.tech/topics/authentication.md>), [BGP](<https://devfeed.tech/topics/bgp.md>)

Tags: [authentication](<https://devfeed.tech/tags/authentication.md>), [bgp](<https://devfeed.tech/tags/bgp.md>), [github](<https://devfeed.tech/tags/github.md>), [is-is](<https://devfeed.tech/tags/is-is.md>), [netlab](<https://devfeed.tech/tags/netlab.md>), [routing](<https://devfeed.tech/tags/routing.md>), [state](<https://devfeed.tech/tags/state.md>)

## AI overview

This lab exercise explains how IS-IS authenticates routing traffic using cleartext passwords or MD5 and SHA hashes. It covers authentication for hello packets and Link State PDUs, and directs readers to launch the lab with GitHub Codespaces or their own infrastructure.

## Source excerpt

Like OSPF and BGP, IS-IS contains a simple mechanism to authenticate routing traffic - IS-IS packets can include a cleartext password or an MD5- or SHA hash. Unlike OSPF, IS-IS can also authenticate: The hello packets exchanged between routers The contents of Link State PDUs flooded across an area or a domain. Want to know more? Check out the Protect IS-IS Routing Data with MD5 Authentication lab exercise. Click here to start the lab in your browser using GitHub Codespaces (or set up your own lab infrastructure). After starting the lab environment, change the directory to feature/3-md5 and execute netlab up.