NestJS NestJS Authentication & Security

Question 1

Which NestJS package integrates Passport.js strategies for authentication?

Accepted Answer

@nestjs/passport

Answer

@nestjs/passport wraps Passport.js strategies into NestJS guards and provides AuthGuard() for route protection.

Question 2

What does `AuthGuard('jwt')` do in NestJS?

Accepted Answer

Validates the JWT token from the request and populates req.user

Answer

AuthGuard('jwt') invokes the Passport JWT strategy to extract, verify, and decode the token, attaching the payload to req.user.

Question 3

Which decorator applies a guard to an entire controller in NestJS?

Accepted Answer

@UseGuards() on the controller class

Answer

@UseGuards() placed on a controller class applies the specified guard(s) to every route handler within that controller.

Question 4

How do you make a single route publicly accessible when JWT auth is applied globally in NestJS?

Accepted Answer

Use a custom @Public() decorator combined with a reflector check in the guard

Answer

A custom @Public() metadata decorator combined with Reflector in the guard's canActivate() allows bypassing JWT validation for specific routes.

Question 5

What is the purpose of the `validate()` method in a Passport strategy class?

Accepted Answer

It receives the decoded token payload and returns the user object to attach to the request

Answer

validate() is called after the token is verified; its return value is attached to req.user and made available to route handlers.

NestJS Practice Test