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Elixir & Phoenix: Scalable Backend Development · Lesson

Channel Authentication and Authorization

Secure your Phoenix Channels by verifying user tokens during the join handshake and authorizing access to specific topics.

Why Channels Need Auth

Channels are long-lived WebSocket connections. Without verification, anyone could join a private topic and read or send messages.

Authentication answers who is connecting, while authorization answers what topics they may join.

The Socket Connect Callback

Authentication starts in connect/3 of your UserSocket. It runs once when the WebSocket opens, before any channel is joined.

def connect(%{"token" => token}, socket, _connect_info) do
  case verify_token(token) do
    {:ok, user_id} -> {:ok, assign(socket, :user_id, user_id)}
    :error -> :error
  end
end

All lessons in this course

  1. Introduction to Phoenix Channels
  2. Broadcasting and Pub/Sub Messaging
  3. Presence and Live Data Updates
  4. Channel Authentication and Authorization
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