PPP

What this chapter covers

The PPP chapter explains the three building blocks that every RouterOS tunnel and dial in service shares.

PPTP, L2TP, PPPoE, SSTP and OpenVPN all create PPP style sessions. Before you configure any of them, you need to know how a session is authenticated, which settings it receives and where its address comes from.

The three building blocks are the profile, the secret and the pool.

How the topics fit together

A client logs in with a secret, the secret selects a profile, and the profile names a pool.

The pieces split the work in a clear way:

• The secret says who the user is, which service they may use and any per user override.
• The profile holds the shared settings, such as addresses, DNS, speed limit and encryption.
• The pool supplies an address for each new session and takes it back afterwards.

Anything set in the secret wins over the same setting in the profile. That is why one profile can serve a whole group while a single user still gets a fixed address.

How to use these pages

Each topic page has the same shape, so you can skim for what you need.

• What it is: the idea in plain words.
• How it works: the mechanism, with diagrams and example commands.
• What to remember for the exam: the facts to memorise.
• Common mistakes: the classic traps.
• Check yourself: three questions to test your understanding.

Read the pages in order, because each one builds on the one before it. The profile page comes first because the secret and the pool are both explained in terms of it. Keep the console open while you read, and try each example command on a lab router.

After the three pages, build a small lab with two routers, one acting as a PPP server and one as a client, and watch the session appear in /ppp active print.