Authentication with requirepass in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the requirepass directive in Redis?

The requirepass directive sets a password that clients must provide to access the Redis server, adding a layer of security.

beginner

How do you enable password authentication in Redis using requirepass?

You add the line requirepass yourpassword in the Redis configuration file (redis.conf) and restart the server.

beginner

What command do you use to authenticate a client connection after requirepass is set?

Use the AUTH yourpassword command to authenticate the client before running other commands.

intermediate

What happens if a client tries to run commands without authenticating when requirepass is set?

Redis will respond with an error: NOAUTH Authentication required. and will not execute the command.

intermediate

Can you change the password set by requirepass without restarting Redis?

Yes, you can change it at runtime using the CONFIG SET requirepass newpassword command (requires current authentication).

What does the requirepass directive do in Redis?

A Enables SSL encryption

B Limits the number of client connections

C Sets a password clients must use to connect

D Enables data persistence

The requirepass directive sets a password that clients must provide to access Redis.

Which command authenticates a client after requirepass is set?

A AUTH password

B CONNECT password

C LOGIN password

D PASS password

The AUTH command is used to authenticate clients with the password.

What error does Redis return if a client runs commands without authenticating when requirepass is set?

A ERR wrong number of arguments

B NOAUTH Authentication required.

C ERR unknown command

D ERR permission denied

Redis returns NOAUTH Authentication required. when commands are run without authentication.

Where do you set the requirepass directive?

A In the Redis configuration file (redis.conf)

B In the Redis client

C In the operating system environment variables

D In the Redis database keys

The requirepass directive is set in the Redis configuration file.

Can you change the requirepass password without restarting Redis?

A No, the password cannot be changed

B No, you must restart Redis

C Yes, by editing the database keys

D Yes, with the CONFIG SET command

You can change the password at runtime using CONFIG SET requirepass newpassword without restarting.

Explain how Redis authentication works when requirepass is set.

Think about what happens before and after a client connects.

Describe the steps to enable and use password authentication in Redis.

Consider both server setup and client actions.

Practice

1. What does the requirepass directive do in Redis?

easy

A. It sets a password that clients must use to authenticate before accessing Redis.

B. It disables all client connections to Redis.

C. It automatically encrypts all data stored in Redis.

D. It sets the maximum number of clients allowed to connect.

Solution

1. Step 1: Understand the purpose of requirepass

   The requirepass directive is used to protect Redis by requiring clients to authenticate with a password.

2. Step 2: Compare options with this purpose

   Only It sets a password that clients must use to authenticate before accessing Redis. describes setting a password for client authentication, matching the purpose of requirepass.

3. Final Answer:

   It sets a password that clients must use to authenticate before accessing Redis. -> Option A

4. Quick Check:

   requirepass = password protection [OK]

Hint: requirepass means password required to connect [OK]

Common Mistakes:

• Thinking requirepass disables connections
• Confusing requirepass with encryption
• Assuming requirepass limits client count

2. Which of the following is the correct way to authenticate a Redis client after requirepass is set?

easy

A. AUTH mypassword

B. LOGIN mypassword

C. CONNECT mypassword

D. PASSWORD mypassword

Solution

1. Step 1: Identify the Redis command for authentication

   Redis uses the AUTH command followed by the password to authenticate clients.

2. Step 2: Check the options for the AUTH command

   Only AUTH mypassword uses the correct AUTH command syntax.

3. Final Answer:

   AUTH mypassword -> Option A

4. Quick Check:

   AUTH command = authenticate password [OK]

Hint: Use AUTH command to send password [OK]

Common Mistakes:

• Using LOGIN instead of AUTH
• Using CONNECT or PASSWORD commands which don't exist
• Forgetting to include the password after AUTH

3. Given the Redis configuration has requirepass foobar set, what will be the output of the following commands sequence?

SET key1 value1
GET key1
AUTH foobar
GET key1

medium

A. OK
(error) NOAUTH Authentication required.
OK
"value1"

B. OK
"value1"
OK
"value1"

C. OK
(error) NOAUTH Authentication required.
(error) NOAUTH Authentication required.
"value1"

D. (error) NOAUTH Authentication required.
(error) NOAUTH Authentication required.
OK
(nil)

Solution

1. Step 1: Understand requirepass effect on commands

   When requirepass is set, all commands except AUTH fail with NOAUTH error until the client authenticates.

2. Step 2: Analyze command sequence

   SET key1 value1 fails with NOAUTH (unauthenticated). GET key1 fails with NOAUTH. AUTH foobar succeeds (OK). GET key1 returns (nil) because the key was never successfully set.

3. Final Answer:

   (error) NOAUTH Authentication required. (error) NOAUTH Authentication required. OK (nil) -> Option D

4. Quick Check:

   Pre-AUTH: NOAUTH errors; post-AUTH: (nil) since key unset [OK]

Hint: Non-AUTH commands fail with NOAUTH before successful AUTH [OK]

Common Mistakes:

• Assuming commands work before AUTH
• Thinking AUTH returns error
• Confusing order of outputs

4. You set requirepass mysecret in your Redis config. A client tries to run AUTH wrongpass followed by GET key. What is the problem and how to fix it?

medium

A. The client must restart Redis; fix by restarting server.

B. The client used wrong password; fix by using correct password with AUTH.

C. requirepass disables GET command; fix by removing requirepass.

D. The client must run AUTH after GET; fix by swapping commands.

Solution

1. Step 1: Identify the error cause

   Using a wrong password with AUTH means client is not authenticated, so GET command will fail with NOAUTH error.

2. Step 2: Correct the authentication process

   Client must provide the correct password with AUTH to authenticate and access commands like GET.

3. Final Answer:

   The client used wrong password; fix by using correct password with AUTH. -> Option B

4. Quick Check:

   Wrong password = no access; correct password fixes it [OK]

Hint: AUTH password must match requirepass exactly [OK]

Common Mistakes:

• Trying commands before successful AUTH
• Thinking requirepass disables commands permanently
• Restarting server unnecessarily

5. You want to change the Redis password without restarting the server. Which command should you use to set a new password newpass123 dynamically?

hard

A. AUTH newpass123

B. SET requirepass newpass123

C. CONFIG SET requirepass newpass123

D. CONFIG GET requirepass

Solution

1. Step 1: Understand how to change requirepass dynamically

   Redis allows changing configuration parameters at runtime using CONFIG SET command.

2. Step 2: Identify correct command to change password

   To change the password, use CONFIG SET requirepass newpass123. AUTH is for client login, SET is for keys, CONFIG GET only reads.

3. Final Answer:

   CONFIG SET requirepass newpass123 -> Option C

4. Quick Check:

   CONFIG SET changes config without restart [OK]

Hint: Use CONFIG SET requirepass to change password live [OK]

Common Mistakes:

• Using AUTH to change password
• Trying SET command for config
• Using CONFIG GET which only reads