In older MS articles they said to use 0xffffffff to completely disable IPv6, but in the article that Joseph references they say not to use that setting because it delays startup (by a whopping 5 seconds). (The article actually shows “f” seven times instead of eight, but I assume it’s a typo.) That said, I have it disabled by using 0xffffffff on all of our 400+ servers and it doesn’t seem to cause any noticeable problems.
*From:* [email protected] [mailto: [email protected]] *On Behalf Of *Michael B. Smith *Sent:* Friday, February 3, 2017 2:06 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 I agree the band should be a bor. Otherwise, I stand by what I wrote. This come out of a 15 element switch statement. In that case, generalities were required. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Joseph L. Casale *Sent:* Friday, February 3, 2017 1:56 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 Actually this is wrong in a couple ways, First, the “binary and” is the check for the condition, what you meant was “binary or” to combine the bit fields. Also, 0xff to disable all IPv6 components, not 0xfffffff. Lastly, anything binary or’ed with 0 is unchanged. In this implementation, its sufficient to simply set the value to 0x20 as (0 | 0x20) == 0x20. https://support.microsoft.com/en-ca/help/929852/how-to-disable-ipv6-or-its-components-in-windows jlc *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Michael B. Smith *Sent:* Friday, February 3, 2017 11:37 AM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 Yes. $value = $enableAll –band $IPv4PrefBit *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Melvin Backus *Sent:* Friday, February 3, 2017 1:25 PM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 For some reason I’m thinking there was a way to make it prefer IPv4 without disabling IPv6. As I said however, it has been a long time so I could be virtualizing that reality. J -- There are 10 kinds of people in the world... those who understand binary and those who don't. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Michael B. Smith *Sent:* Friday, February 3, 2017 10:37 AM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 It does apply to Exchange, but the same “not supported” comment comes into play. >From a bit of PowerShell I have for server core… ### Hive = HKLM [string]$ipv6_keyName = "SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters" [string]$ipv6_valueName = "DisabledComponents" [int]$disableAll = 0xffffffff [int]$enableAll = 0 [int]$tunnelBit = 0x01 [int]$nonTunnelBit = 0x10 [int]$IPv4PrefBit = 0x20 *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Melvin Backus *Sent:* Friday, February 3, 2017 9:48 AM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 I seem to recall there being reg hack for Windows that would make IPv4 the preferred choice. I don’t know if applies to Exchange or not, and it’s been a few years since I looked at it. -- There are 10 kinds of people in the world... those who understand binary and those who don't. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Michael B. Smith *Sent:* Friday, February 3, 2017 9:21 AM *To:* [email protected] *Subject:* RE: [NTSysADM] Exchange sending via IPv6 This is 2017 and it doesn’t speak IPv6? Yes, Exchange starting with 2013 will definitely prefer IPv6 over IPv4. *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Kelsey, John *Sent:* Friday, February 3, 2017 8:15 AM *To:* '[email protected]' *Subject:* RE: [NTSysADM] Exchange sending via IPv6 Yes, the Sophos appliance is set as a smart host. I’m currently using the FQDN of the appliance. I’ll try using its IPv4 address. Thanks! *From:* [email protected] [ mailto:[email protected] <[email protected]>] *On Behalf Of *Kurt Buff *Sent:* Thursday, February 02, 2017 11:57 PM *To:* ntsysadm *Subject:* Re: [NTSysADM] Exchange sending via IPv6 Are you using the Sophos appliance as a smarthost? Are you using the FQDN of the appliance, or its IPv4 address? If the former, try the latter. I'd verify the vendor's claim, BTW - "netsh trace" is your friend: https://msdn.microsoft.com/en-us/library/windows/desktop/dd569142(v=vs.85).aspx and https://blogs.msdn.microsoft.com/canberrapfe/2012/03/30/capture-a-network-trace-without-installing-anything-capture-a-network-trace-of-a-reboot/ Kurt On Thu, Feb 2, 2017 at 8:13 PM, Kelsey, John <[email protected]> wrote: Working on a new Exchange 2013 install. Outbound emails are failing and our front-end email appliance vendor (Sophos) says its failing because Exchange is sending the outbound emails using its ipv6 address instead of its ipv4 address and the Sophos appliance doesn’t understand ipv6 ( I know, right?) I don’t see any obvious place to configure this in Exchange, and I know that disabling ipv6 in Exchange is baaaaaad. So can I force Exchange to send only using its ipv4 address somehow? Thanks all. *************************************** *John C. Kelsey, MCSE, CCNA*Network Architect Penn Highlands Healthcare (: 814.375.3073 <(814)%20375-3073> 2 : 814.375.4005 <(814)%20375-4005> *: [email protected] *************************************** This email and any attached files are sensitive in nature and intended solely for the intended recipient(s). If you are not the named recipient you should not read, distribute, copy or alter this email. Any views or opinions expressed in this email are those of the author and do not represent those of Penn Highlands Healthcare or its affiliates.. Warning: Although precautions have been taken to make sure no viruses are present in this email, the company cannot accept responsibility for any loss or damage that arise from the use of this email or attachments. This email and any attached files are sensitive in nature and intended solely for the intended recipient(s). If you are not the named recipient you should not read, distribute, copy or alter this email. Any views or opinions expressed in this email are those of the author and do not represent those of Penn Highlands Healthcare or its affiliates.. Warning: Although precautions have been taken to make sure no viruses are present in this email, the company cannot accept responsibility for any loss or damage that arise from the use of this email or attachments.
