Bug #83649 IPv6 connections do not work
Submitted: 2 Nov 2016 11:11 Modified: 15 Oct 2019 7:50
Reporter: Michiel Hazelhof Email Updates:
Status: Closed Impact on me:
Category:Connector / NET Severity:S1 (Critical)
Version:7.0.6m5 OS:Any
Assigned to: CPU Architecture:Any
Tags: ipv6

[2 Nov 2016 11:11] Michiel Hazelhof
We are lucky enough to have a few connections which are IPv6 only, unfortunately this doesn't play well with the .net connector.

The connection is made via hostname which resolves to both IPv4 and a IPv6 addresses (obviously only the IPv6 is available for the machines in question).

Other SQL tools can connect from the IPv6 only connection to the same database server, the problem appears to reside exclusively in the .net connector.

How to repeat:
Use a computer with both IPv4 and IPv6 connectivity and simply disable IPv4 or a machine on a IPv6 only connection (hard to come by).
[3 Nov 2016 6:13] Chiranjeevi Battula
Hello  Michiel Hazelhof,

Thank you for the bug report.
Verified as described.

[3 Nov 2016 9:04] Michiel Hazelhof
Temporary fix, not the greatest (I *hope* that TcpClient should be able to handle it just by the hostname, but apperantely I cannot find the correct settings to do so).

        private static Stream GetTcpStream(MySqlConnectionStringBuilder settings)
            IPHostEntry host = Dns.GetHostEntry(settings.Server);
            foreach (IPAddress ipAddress in host.AddressList)
                if (ipAddress.AddressFamily != AddressFamily.InterNetwork && ipAddress.AddressFamily != AddressFamily.InterNetworkV6) continue;

                TcpClient client = new TcpClient(ipAddress.AddressFamily);
                Task task = client.ConnectAsync(settings.Server, (int)settings.Port);

                if (!task.Wait(((int)settings.ConnectionTimeout * 1000)))
                    throw new MySqlException(Resources.Timeout);
                return client.GetStream();
                //TODO:  reimplement or remove keepalive

            throw new MySqlConversionException(Resources.UnableToConnectToHost);
[4 Nov 2016 12:16] Michiel Hazelhof
Quick fix to support ip based hosts:

            IPAddress parsed;
            IPAddress.TryParse(settings.Server, out parsed);
            IPHostEntry host = parsed != null ? new IPHostEntry { AddressList = new[] { parsed } } : Dns.GetHostEntry(settings.Server);
[14 Oct 2019 17:28] Bradley Grainger
Should this bug now be closed because it's fixed in 8.0.18?


> Connector/NET now supports IPV6 connections made using the classic MySQL protocol when the operating system on the server host also supports IPV6. (Bug #29682333)
[15 Oct 2019 7:50] Michiel Hazelhof
Verified working, can be closed