How to Install and Secure Redis Server on Ubuntu 24.04 VPS (Production Hardened)

The Critical Role of Redis in High-Scale Architectures

Redis (Remote Dictionary Server) is the industry standard for in-memory key-value data structures. By storing session states, API responses, and database query objects in RAM rather than reading from disk, Redis enables web applications to serve tens of thousands of requests per second. However, because Redis is designed for high performance rather than perimeter defense, securing its configuration is paramount.

Step 1: Installing Redis from Official Repositories

sudo apt update
sudo apt install -y redis-server

Step 2: Hardening the Redis Configuration File

Open /etc/redis/redis.conf:

sudo nano /etc/redis/redis.conf

A. Enable Systemd Supervision

Find the supervised directive and change it from no to systemd:

supervised systemd

B. Bind Exclusively to Localhost

Never expose Redis to 0.0.0.0 unless protected by an encrypted VPN tunnel or private VPC subnet:

bind 127.0.0.1 ::1
protected-mode yes

C. Enforce Strong Cryptographic Password

Redis can process over 150,000 authentication attempts per second, meaning simple passwords can be cracked in minutes. Generate a 64-character password and apply it:

# Generate password
openssl rand -base64 32

# Set in redis.conf:
requirepass YOUR_64_CHARACTER_RANDOM_PASSWORD

D. Configure Memory Caps and Eviction Policies

Prevent Redis from consuming all server memory and triggering the Linux OOM killer:

maxmemory 2gb
maxmemory-policy allkeys-lru

Step 3: Restarting and Verifying Redis

sudo systemctl restart redis-server
sudo systemctl enable redis-server

# Test connection via redis-cli
redis-cli
127.0.0.1:6379> ping
(error) NOAUTH Authentication required.
127.0.0.1:6379> auth YOUR_64_CHARACTER_RANDOM_PASSWORD
OK
127.0.0.1:6379> ping
PONG

Frequently Asked Questions (FAQ)

What is the best maxmemory-policy for WordPress?

For WordPress object caching, use allkeys-lru (Least Recently Used) or volatile-lru. This ensures that when memory fills up, Redis drops the oldest unrequested keys rather than refusing new write operations.