Authentication with requirepass in Redis - Step-by-Step Execution

Concept Flow - Authentication with requirepass

Start Redis Server

↓

Check requirepass set?

No→Allow all commands

Yes↓

Client connects

↓

Client sends AUTH command with password

↓

Check password correctness

↓

Allow commands

↓

Client executes allowed commands

↓

End or disconnect

This flow shows how Redis checks if a password is set, then requires clients to authenticate before allowing commands.

Execution Sample

Redis

requirepass mysecret
Client: AUTH mysecret
Client: SET key value
Client: GET key

This example shows a Redis server requiring a password, client authenticating, then setting and getting a key.

Execution Table

Step	Action	Input/Command	Check	Result	Client Allowed?
1	Start Redis server	requirepass mysecret	Is requirepass set?	Yes	No commands allowed until AUTH
2	Client connects	CONNECT	N/A	Connection accepted	No commands allowed until AUTH
3	Client sends AUTH	AUTH mysecret	Password matches?	Yes	Commands allowed
4	Client sends SET	SET key value	Authenticated?	Yes	Command executed, key set
5	Client sends GET	GET key	Authenticated?	Yes	Command executed, value returned
6	Client sends AUTH wrongpass	AUTH wrongpass	Password matches?	No	Command rejected with error
7	Client sends GET without AUTH	GET key	Authenticated?	No	Command rejected with error

💡 Commands are only allowed after successful AUTH; wrong or missing password causes rejection.

Variable Tracker

Variable	Start	After Step 3	After Step 4	After Step 5	After Step 6	After Step 7
Authenticated	False	True	True	True	False (for that AUTH attempt)	False
Key 'key'	None	None	"value"	"value"	"value"	"value"

Key Moments - 3 Insights

Why can't the client run SET before AUTH?

Because requirepass is set, Redis blocks all commands except AUTH until the client authenticates (see execution_table step 1 and 3).

What happens if the client sends the wrong password?

Redis rejects the AUTH command and does not allow further commands (see execution_table step 6).

Does the client stay authenticated after a failed AUTH attempt?

No, a failed AUTH does not grant access; the client remains unauthenticated (see variable_tracker 'Authenticated' after step 6).

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the client become authenticated?

A Step 3

B Step 4

C Step 2

D Step 6

💡 Hint

Check the 'Authenticated' variable in variable_tracker after each step.

According to the execution_table, what happens if the client sends GET before AUTH?

A Command executes and returns value

B Command rejected with error

C Client disconnects

D Password is requested again

💡 Hint

Look at step 7 in the execution_table for GET without AUTH.

If requirepass was not set, what would change in the execution flow?

A Server rejects all connections

B Client must still send AUTH

C All commands allowed without AUTH

D Server crashes

💡 Hint

See the decision at 'Is requirepass set?' in concept_flow.

Concept Snapshot

Redis requirepass sets a password for clients.
Clients must send AUTH with the correct password before running commands.
Without AUTH, commands are rejected.
Wrong password causes rejection.
If requirepass is not set, no authentication is needed.

Full Transcript

This visual execution shows how Redis uses requirepass to protect commands. When the server starts with requirepass set, clients must authenticate by sending AUTH with the correct password. Until then, commands like SET or GET are rejected. If the password is correct, commands are allowed. Wrong passwords cause rejection and no access. If requirepass is not set, clients can run commands immediately without AUTH. Variables like 'Authenticated' track client state. This helps beginners see step-by-step how authentication controls access in Redis.