IPV6 connection problem

Question

Hello, I connecting to ftp for example ftp.ripe.net by IPV4 connection protocol. Everything is ok. Next when I make new connection to ipv6 and make the same connect to ftp.ripe.net. I got error message:

12:43:28 - Error message: Could not connect to server. A socket operation was attempted to an unreachable network 193.0.6.140:21

I prepared trace.
IPV4 is ok DNS resolve and connect to FTP
IPV6 missing DNS resolve and FTP connect too

How we can use ftp -> IPV6

Thanx

Answer 1

Hello,

IPv6 is supported by Rebex FTP client. At the moment Rebex FTP prefers IPv4 addresses and only uses IPv6 address if no IPv4 address is available for a hotname.

I prepared a code that tries to connect to the first IPv6 address available and it reports that there are actually no IPv6 addresses for the "ftp.ripe.net" FTP server.

        IPHostEntry ipEntry = Dns.GetHostEntry("ftp.ripe.net");
        IPAddress[] addresses = ipEntry.AddressList;

        IPAddress ipv6 = null;
        foreach (var address in addresses)
        {
            if (address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6)
            {
                ipv6 = address;
                break;
            }
        }

        if (ipv6 == null)
            throw new ApplicationException("No IPv6 address");

        Ftp ftp = new Ftp();
        ftp.Connect(ipv6.ToString());

Running the code, are you sure there is an IPv6 address for your FTP server?