Why Your VPN Tunnel Breaks at Midnight (and How to Stop It)
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Why Your VPN Tunnel Breaks at Midnight (and How to Stop It)
It’s 11:59
PM. You’re brushing your teeth. Ping.
The monitoring system lights up: VPN tunnel down.
If this happens every night at midnight, you’re not cursed—it’s timers, certificates, or clocks conspiring against you.
This article breaks down why VPN tunnels (IPsec/IKE) often fail at predictable times like midnight, how to diagnose the root cause, and what you can do to make sure you never lose sleep over a rekey again.
The Midnight Pattern
Why midnight? Because humans love round numbers.
- Security admins configure 24-hour lifetimes.
- Certificate management systems often issue certs tied to calendar days.
- Cron jobs and automated scripts default to midnight.
So when the stars align (bad timers + sloppy configs + NTP drift), tunnels predictably fail just as you’re clocking out.
The Usual Suspects
1. IKE Security Association (SA) Lifetime
- By default, many firewalls/vendors use a 24-hour Phase 1 (IKE SA) lifetime.
- If two peers negotiate different timers, the rekey will fail at expiration.
- Rekeys often happen right around midnight if the SA was established the day before at that time.
Example (Palo Alto default):
IKEv2 SA lifetime: 28800 seconds (8 hours)IPSec SA lifetime: 3600 seconds (1 hour)