demo ยท v139
Chrome 139 randomizes TCP source ports on eligible Windows releases instead of walking the ephemeral range in order. The simulator keeps the same held-port pressure for both strategies so the security, collision, and exhaustion branches are visible side by side.
simulation controls
pre-v139 Windows
Sequential assignment avoids some reuse by walking forward, but every successful allocation moves the next guess by a visible amount.
Chrome 139 on eligible Windows
Randomization hides the next source port, but a small or crowded ephemeral range creates retry pressure before the connection pool can recover.
observer view
The old behavior lets an observer compare before/after source ports and estimate how many other sockets advanced the counter. Randomized ports turn the delta into noise.
trial log
Sequential allocation makes the next source port a one-step guess once a site or network observer has seen the counter. Random allocation forces guesses across the free ephemeral pool.
Random sampling can re-pick ports still held by recent connections. Chrome enables the change on Windows versions where the ephemeral range is wide enough to keep that collision rate acceptable.
When no usable source port is found, the browser and network stack have to queue, reuse idle pooled sockets, back off, or fail the connection attempt instead of opening another TCP socket.