rfc2766_5.3.2_checksum_tcp_udp.seq - Verify IPv6 <-> IPv4 header
translation in accordance with RFC2766 [NATPT]
Router
rfc2766_5.3.2_checksum_tcp_udp.seq [-tooloption ...]
-p rfc2766_5.3.2_checksum_tcp_udp.def
Before this test starts, run initialize_natpt.seq.
This test verifies that NUT adjusts header checksum for TCP/UDP
packets.
Network Topology
Link0
--------------------------
| |
TN NUT
| |
--------------------------
Link1
TN -- (Link0) -- NUT NUT -- (Link1) -- TN
--------------------- ------------------------
1.1.
===================>
IPv6 UDP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
UDP packet
Checksum including IPv6 pseudo header
data = repeat(0xff,128)
1.2.
<<JUDGMENT>>
===================>
IPv4 UDP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
DF = 1
UDP packet
Checksum including IPv4 pseudo header, or zero
data = repeat(0xff,128)
2.1.
===================>
IPv6 UDP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
Fragment Header
More fragments = 1
UDP packet
Checksum including IPv6 pseudo header, or zero
data = repeat(0xff,64)
2.2.
<<JUDGMENT>>
===================>
IPv4 UDP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
MF = 1
UDP packet
Checksum for full UDP packet, including pseudo header
data = repeat(0xff,64)
3.1.
===================>
IPv6 UDP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
Fragment Header
More fragments = 0
NextHeader = 17
Payload
data = repeat(0xff,64)
3.2.
<<JUDGMENT>>
===================>
IPv4 UDP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
MF = 0
Protocol = 17
Payload
data = repeat(0xff,64)
4.1.
===================>
IPv6 TCP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
TCP packet
Checksum including IPv6 pseudo header
data = repeat(0xff,128)
4.2.
<<JUDGMENT>>
===================>
IPv4 TCP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
DF = 1
TCP packet
Checksum including IPv4 pseudo header
data = repeat(0xff,128)
5.1.
===================>
IPv6 TCP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
Fragment Header
More fragments = 1
TCP packet
Checksum including IPv6 pseudo header
data = repeat(0xff,64)
5.2.
<<JUDGMENT>>
===================>
IPv4 TCP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
MF = 1
TCP packet
Checksum including IPv4 pseudo header
data = repeat(0xff,64)
6.1.
===================>
IPv6 TCP packet
IPv6 Header
src address : TN LINK0 IPv4 embedded IPv6 address
dst address : TN LINK1 IPv4 embedded IPv6 address
Fragment Header
More fragments = 0
Payload
data = repeat(0xff,64)
6.2.
<<JUDGMENT>>
===================>
IPv4 TCP packet
IPv4 Header
src address : TN LINK0 IPv4 address
dst address : TN LINK1 IPv4 address
MF = 0
Payload
data = repeat(0xff,64)
<< PASS >>
NUT adjusts header checksum for UDP/TCP packets.
Optionally NUT sets checksum to zero on UDP packets.
<< FAIL >>
NUT send TCP/UDP packets with wrong checksum.
RFC2766
5.3.2 TCP/UDP/ICMP Checksum Update from IPv6 to IPv4
TCP and UDP checksums SHOULD be recalculated to reflect the address change from v6 to v4. The incremental checksum adjustment algorithm may be borrowed from [NAT]. In the case of NAPT-PT, TCP/UDP checksums should be adjusted to account for the address and TCP/UDP port changes, going from V6 to V4 addresses. For UDP packets, optionally, the checksum may simply be changed to zero.
perldoc V6evalTool