[strongSwan] Query reg UDP encapsulation for IPv6

Mukesh Yadav write2mukesh84 at gmail.com
Wed Apr 15 19:56:34 CEST 2015


What is behavior when Strong-swan is used for IKE exchange and tunnel end
points are IPv6.
Does it allow/process UDP-encapsulated Ipv6 packets when NATT is not


On 15 April 2015 at 21:46, Mukesh Yadav <write2mukesh84 at gmail.com> wrote:

> Hi Ryan,
> Definitely NAT is not needed in case of IPv6 tunnel end-points.
> But RFC 5996 doesn't clearly say something about it.
> Also there mentioned a use-case in RFC-5996 where firewalls might have
> been configured for only UDP(port based) traffic to by-pass.
> In that case peer might be using UDP-encapsulation for IPv6 tunnel even if
> NATT is not detected..
> Thanks
> Mukesh
> On 15 April 2015 at 19:45, Ruel, Ryan <rruel at akamai.com> wrote:
>>  Mukesh,
>>  I believe the idea is that for IPv6, NAT will not be needed (that's the
>> beauty of having so much address space!).
>>  Technically, sure, you could NAT IPv6.  But why?
>>  /Ryan
>>   From: Mukesh Yadav <write2mukesh84 at gmail.com>
>> Date: Wednesday, April 15, 2015 at 9:56 AM
>> To: "users at lists.strongswan.org" <users at lists.strongswan.org>
>> Subject: [strongSwan] Query reg UDP encapsulation for IPv6
>>   HI,
>>  My question is more towards IKEv2 standard rather strongswan explicitly.
>> UDP encasulation is used for NATT traversal in IPsec for both ESP/IKE.
>>  RFC 5996, says even if NATT is not detection sending IKE/ESP on 4500 is
>> optional but receiving should be handled.
>> RFC 5666 reference:
>> *"When either side is using port 4500, sending ESP with UDP encapsulation
>> is*
>> *   not required, but understanding received UDP-encapsulated ESP packets
>> is required"*
>>  Having said that this all fine for IPv4, but for IPv6 is it possible
>> that NATT is not detection and still IKE/ESP exchanges are done on port
>> 4500 as UDP encapsulated.
>>  One reference from RFC I can is below which says that IKE/ESP can
>> always be on port 4500 even if NAT not detected, but not clear whether same
>> is applicable for IPv6 as well.
>> *" IKEv2 will use UDP encapsulation of IKE and ESP packets. This encoding
>> is slightly less*
>> *   efficient but is easier for NATs to process.  In addition, firewalls*
>> *   may be configured to pass UDP-encapsulated IPsec traffic but not
>> plain, unencapsulated ESP/AH or vice versa."*
>>  Any opinion or suggestion for same will appreciated.
>>  Thanks
>> Mukesh
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