Preface

Every Mac has a hidden expiration date. After exactly 49 days, 17 hours, 2 minutes, and 47 seconds of continuous uptime, a 32-bit unsigned integer overflow in Apple’s XNU kernel freezes the internal TCP timestamp clock. Once frozen, TIME_WAIT connections never expire, ephemeral ports slowly exhaust, and eventually no new TCP connections can be established at all. ICMP (ping) keeps working. Everything else dies. The only fix most people know is a reboot. We discovered this bug on our iMessage service monitoring fleet, reproduced it live on two machines, and traced the root cause to a single comparison in the XNU kernel source. This is the full story.

Source: we found a ticking time bomb in macos tcp networking - photon blog

It’s surprising that Mac OS still has an unsigned 32-bit integer issue, given how much they celebrated being as the first all 64-bit OS. It was in 2017 that Apple required all applications to be 64-bit.