Management port closure is not handled correctly

[starlightcrafted]

Before filing a Bug Report

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What you expect to be happening.

ZeroTier Client shuts down and management ports are cleared

What is actually happening?

ZeroTier Client does not seem to set SO_REUSEADDR, or there is something else not releasing the port, so the management port cannot be immediately reused if the management port receives HTTP calls right before restarting or if a HTTP client keeps the connection open while it is restarting.

On restart, the ZeroTier Client starts emitting the error /usr/sbin/zerotier-one: fatal error: cannot bind to local control interface port 9993 and fails to restart until the time defined at /proc/sys/net/ipv4/tcp_tw_recycle has passed.

Any steps to reproduce the error.

Run the below bash script in one window. Restart ZeroTier Client in another.

This is a simple script to simulate the ZeroTier Client restarting while a there is still a connection to the management port.

#!/bin/bash

while true
do
telnet localhost 9993
done

Using some debugging tools like ss you can now see there are left over TCP-WAIT connections.

ss state time-wait sport = 9993

Which can then be killed using

ss state time-wait sport = 9993 -K

A quick fix in case someone else experiences this is to just add the following to /etc/systemd/system/zerotier-one.service.d/kill.conf

[Service]
ExecStartPre=/usr/bin/ss state time-wait sport = 9993 -K

Any relevant console output or screenshots.

What operating system and ZeroTier version. Please try the latest ZeroTier release.

Ubuntu 24.04
ZeroTier 1.14.0