Session Management
After users authenticate, you need to remember who they are across requests. Sessions track logged-in users, but poor session management creates security vulnerabilities. Getting this right protects your users.
Session Security Fundamentals
Regenerate session IDs on login. If an attacker tricks a user into using a known session ID before login (session fixation), they gain access after the user authenticates. Creating a new session ID on login prevents this.
Configure cookies properly. Set Secure so cookies only transmit over HTTPS. Set HttpOnly to prevent JavaScript access (protecting against XSS). Set SameSite=Lax or Strict to prevent CSRF attacks.
Set reasonable expiration. Balance security (shorter is safer) with usability (users hate re-logging in). Consider absolute timeouts (maximum session length) and idle timeouts (time since last activity).
Invalidate sessions properly on logout. Don't just delete the client's cookie — destroy the session on the server. Otherwise, an attacker with the session ID can still use it.
Session Storage Options
Memory storage works for single-server development but fails when you scale. Sessions disappear on restart and can't be shared across servers.
Redis is the recommended choice for production. It's fast, supports expiration natively, and enables horizontal scaling. All your servers can access the same session data.
Database storage works but adds latency to every request. It's acceptable for low-traffic applications or when you need session data in queries.
Token Refresh Pattern
For JWT-based sessions, use short-lived access tokens with longer-lived refresh tokens:
Access token: 15 minutes
Refresh token: 7 days (stored securely)
When access token expires:
1. Client sends refresh token to dedicated endpoint
2. Server validates refresh token
3. Server issues new access token
4. Optionally rotate refresh token (more secure)
This limits the damage window if an access token is stolen while keeping users logged in.
Multi-Device Considerations
Users expect to be logged in on multiple devices simultaneously. Track active sessions so users can see where they're logged in. Provide "log out everywhere" functionality for when devices are lost or compromised. Consider showing session history — location, device type, last activity — so users can spot unauthorized access.
Store enough metadata to make sessions identifiable without storing sensitive information that could be exploited.