rfc2765_3.3_icmpv4error.seq - Verify IPv6 <-> IPv4 header
translation in accordance with RFC2765 [SIIT]
Router
rfc2765_3.3_icmpv4error.seq [-tooloption ...]
-p rfc2765_3.3_icmpv4error.def
Before this test starts, run initialize.seq.
This test verifies that NUT can translate ICMPv6 error messages
in accordance to RFC2765.
Network Topology
Link0
--------------------------
| |
TN NUT
| |
--------------------------
Link1
TN -- (Link0) -- NUT NUT -- (Link1) -- TN
--------------------- ------------------------
ICMPv6 (Type 1, Code 0) => ICMPv4 (Type 3, Code 1) ICMPv6 (Type 1, Code 1) => ICMPv4 (Type 3, Code 10) ICMPv6 (Type 1, Code 2) => ICMPv4 (Type 3, Code 1) ICMPv6 (Type 1, Code 3) => ICMPv4 (Type 3, Code 1) ICMPv6 (Type 1, Code 4) => ICMPv4 (Type 3, Code 3) ICMPv6 (Type 2, Code 0, MTU 1280) => ICMPv4 (Type 3, Code 4, MTU 1252) ICMPv6 (Type 3, Code 0) => ICMPv4 (Type 11, Code 0) ICMPv6 (Type 4, Code 0, Pointer 0) <= ICMPv4 (Type 12, Code 0, Pointer 0) ICMPv6 (Type 4, Code 0, Pointer 4) <= ICMPv4 (Type 12, Code 0, Pointer 2) ICMPv6 (Type 4, Code 0, Pointer 6) <= ICMPv4 (Type 12, Code 0, Pointer 9) ICMPv6 (Type 4, Code 0, Pointer 7) <= ICMPv4 (Type 12, Code 0, Pointer 8) ICMPv6 (Type 4, Code 0, Pointer 8) <= ICMPv4 (Type 12, Code 0, Pointer 12) ICMPv6 (Type 4, Code 0, Pointer 24) <= ICMPv4 (Type 12, Code 0, Pointer 16) ICMPv6 (Type 4, Code 0, Pointer 1) <= ICMPv4 (Type 12, Code 0, Pointer -1) ICMPv6 (Type 4, Code 1) => ICMPv4 (Type 3, Code 2)
<< PASS >>
NUT translates ICMPv6 error messages in accordance with
RFC2765, including translating the inner IP-header.
<< FAIL >>
NUT fails to translate ICMPv6 errors correctly, or doesn't
drop untranslatable ICMPv6 error types.
RFC2765
4.2. Translating ICMPv6 Headers into ICMPv4 Headers
All ICMP messages that are to be translated require that the ICMP checksum field be updated as part of the translation since ICMPv6, unlike ICMPv4, has a pseudo-header checksum just like UDP and TCP.
In addition all ICMP packets need to have the Type value translated and for ICMP error messages the included IP header also needs translation.
The actions needed to translate various ICMPv6 messages are:
ICMPv6 error messages:
Destination Unreachable (Type 1)
Set the Type field to 3. Translate the code field as
follows:
Code 0 (no route to destination):
Set Code to 1 (host unreachable).
Code 1 (communication with destination administratively
prohibited):
Set Code to 10 (communication with destination host
administratively prohibited).
Code 2 (beyond scope of source address):
Set Code to 1 (host unreachable). Note that this
error is very unlikely since the IPv4-translatable
source address is considered to have global scope.
Code 3 (address unreachable):
Set Code to 1 (host unreachable).
Code 4 (port unreachable):
Set Code to 3 (port unreachable).
Packet Too Big (Type 2)
Translate to an ICMPv4 Destination Unreachable with code 4.
The MTU field needs to be adjusted for the difference between
the IPv4 and IPv6 header sizes taking into account whether or
not the packet in error includes a Fragment header.
Time Exceeded (Type 3)
Set the Type to 11. The Code field is unchanged.
Parameter Problem (Type 4)
If the Code is 1 translate this to an ICMPv4 protocol
unreachable (Type 3, Code 2). Otherwise set the Type to 12
and the Code to zero. The Pointer needs to be updated to
point to the corresponding field in the translated include IP
header.
Unknown error messages
Silently drop.
http://www.cs.washington.edu/research/networking/napt/reports/usenix98/
A.4 Translating ICMPv6 to ICMPv4
Parameter Problem (Type 4):
If the Code is 2 then set Type to 12, Code to 0, and Pointer to -1.
If the Code is 1 translate this to an ICMPv4 protocol unreachable
(Type 3, Code 2) message.
If the Code is 0 then set the Type to 12, the Code to 0, and
translate the Pointer values as follows:
0-to-0, 4-to-2, 7-to-8, 6-to-9, 8-to-12, 24-to-16, and for all
other ICMPv6 Pointer values set the ICMPv4 Pointer value to -1.
perldoc V6evalTool