Request.UserHostAddress, Vista & IIS7

Discussion in 'ASP .Net' started by Mark Rae, Apr 26, 2007.

  1. Mark Rae

    Mark Rae Guest

    Hi,

    Now that the VS.NET 2005 SP1 update patch is with us, I'm in the process of
    moving my main development environment onto 64-bit Vista Business Edition -
    so far, so good...

    However, there is a bit of a gotcha with Request.UserHostAddress...

    Under IIS6 and earlier, that would return a standard xxx.xxx.xxx.xxx IP
    address. However, Vista enables IP6 by default, which makes
    Request.UserHostAddress return an IP6 address e.g.
    "fe80::2032:39ab:3f57:fffb%10"

    Easy enough to disable IP6, of course, but does anyone know a way to return
    an IP4 address from IIS7 without disabling IP6, or mucking about with
    LMHOSTS...

    Haven't been able to find a way so far...
    http://west-wind.com/WebLog/posts/8839.aspx
    http://forums.asp.net/thread/1667538.aspx

    Any assistance gratefully received.

    Mark
     
    Mark Rae, Apr 26, 2007
    #1
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  2. This article shows you how to set Vista to prefer IPv4 to IPv6 when attempting connections:

    http://www.microsoft.com/technet/community/columns/cableguy/cg1005.mspx

    To selectively disable Pv6 components and configure behaviors for IPv6 in Windows Vista,
    create and configure the following registry value (DWORD type):

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\tcpip6\Parameters\DisabledComponents

    DisabledComponents is set to 0 by default.

    The DisabledComponents registry value is a bit mask that controls the following series of flags,
    starting with the low order bit (Bit 0):

    Bit 0 Set to 1 to disable all IPv6 tunnel interfaces, including ISATAP, 6to4, and Teredo tunnels.
    Default value is 0.

    Bit 1 Set to 1 to disable all 6to4-based interfaces. Default value is 0.

    Bit 2 Set to 1 to disable all ISATAP-based interfaces. Default value is 0.

    Bit 3 Set to 1 to disable all Teredo-based interfaces. Default value is 0.

    Bit 4 Set to 1 to disable IPv6 over all non-tunnel interfaces, including LAN interfaces and
    Point-to-Point Protocol (PPP)-based interfaces. Default value is 0.

    Bit 5 Set to 1 to modify the default prefix policy table to prefer IPv4 to IPv6 when
    attempting connections. Default value is 0.

    So, you'd set the first 4 bits to 0 and bit 5 to 1.

    That will allow IPv6, but the system will prefer IPv4.

    To only prefer IPv4 over IPv6 (what you want), set the value to 0x20
    To disable IPv6 over all interfaces *and* prefer IPv4 to IPv6, set it to 0xFF

    You must restart the computer for the changes to the DisabledComponents registry value to take
    effect.
     
    Juan T. Llibre, Apr 26, 2007
    #2
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  3. Mark Rae

    Mark Rae Guest

    Superb! Muchas gracias, hombron...
     
    Mark Rae, Apr 27, 2007
    #3
  4. re:
    <chuckle>

    You're quite welcome, Mark.
    It just so happened that I'd just looked up the very same issue for a client.

    :)
     
    Juan T. Llibre, Apr 27, 2007
    #4
  5. Mark Rae

    Mark Rae Guest

    Aw - now you've gone and shattered my illusion...
     
    Mark Rae, Apr 27, 2007
    #5
  6. The timing was perfect... :)
     
    Juan T. Llibre, Apr 27, 2007
    #6
  7. Mark Rae

    Mark Rae Guest

    I think I've found a way to return the IP4 address even when IP6 is on...

    Dns.GetHostAddresses(Dns.GetHostName()) returns an array if IP addresses for
    the current host and, so far, the IP4 address always seems to be the fourth
    element of the array i.e.

    [0]: {fe80::288f:1d8f:3f57:fffb%10}
    [1]: {fe80::7133:8615:3971:49d1%8}
    [2]: {fe80::5efe:192.168.0.4%13}
    [3]: {192.168.0.4}
    [4]: {2001:0:4136:e38e:288f:1d8f:3f57:fffb}

    Therefore:

    using System.Net;
    string strIP4Address =
    Dns.GetHostAddresses(Dns.GetHostName())[3].ToString();

    I need to do a bit more testing to see what that returns on XP / Win2k3s.

    Also, it's almost certainly an extremely bad idea to rely on the numerical
    position of the element within the array...
     
    Mark Rae, Apr 29, 2007
    #7
  8. Mark Rae

    Mark Rae Guest

    And here we go:

    using System.Net;

    public string GetIP4Address()
    {
    string strIP4Address = String.Empty;

    foreach (IPAddress objIP in Dns.GetHostAddresses(Dns.GetHostName()))
    {
    if (objIP.AddressFamily.ToString() == "InterNetwork")
    {
    strIP4Address = objIP.ToString();
    break;
    }
    }
    return strIP4Address;
    }

    See here for further details:
    http://msdn2.microsoft.com/en-us/library/system.net.ipaddress.addressfamily.aspx
     
    Mark Rae, Apr 29, 2007
    #8
  9. Good job, Mark!




     
    Juan T. Llibre, Apr 29, 2007
    #9
  10. Mark Rae

    Mark Rae Guest

    Thanks.
     
    Mark Rae, Apr 29, 2007
    #10
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