NAME

        SV_RFC2181_4_1_source_selection - UDP Source Address Selection

VERIFICATION POINTS

        Verify that a NUT selects the correct Source Address.

Servers when responding to queries using UDP must cause the reply to be sent with the source address field in the IP header set to the address that was in the destination address field of the IP header of the packet containing the query causing the response.

TARGET

        Authoritative Server

SYNOPSIS

	SV_RFC2181_4_1_source_selection.seq [-tooloption ...]: KOI tool option
	See also DNSConfig.pm

INITIALIZATION

Network Topology

        AP Server1 (TN)
          |3ffe:501:ffff:101::10
          |192.168.1.10
          |
Net-y   --+--------+-------------------------- 3ffe:501:ffff:101::/64 
                   |                           192.168.1/24
                   |
                   |
                 Router (TN)
                   |3ffe:501:ffff:100::1
                   |192.168.0.1
                   |
                   |
Net-z   --+--------+-----------------+-------- 3ffe:501:ffff:100::/64 
          |                          |          192.168.0/24
          |                          |
        DNS Server1 (NUT)            DNS Client1 (TN)
           3ffe:501:ffff:100::XXXX     3ffe:501:ffff:100::20 
           3ffe:501:ffff:100::11       192.168.0.20
           192.168.0.10
           192.168.0.11
	

	XXXX: EUI64

Setup

Set the DNS Server1's (NUT) address as above mentioned Network Topology.

Configure the Server1's (NUT) zone file to response query from TN.

Example of example.com zone file:

$TTL    86400           ; TTL of 1 day
@ IN SOA NS1.example.com. root.example.com. (
	2005081600	; serial
	3600		; refresh every 1 hr
	900		; retry every 15 min
	604800		; expire after a week
	3600		; Minimum TTL of a 1 hr
)
;
	IN	NS	NS1.example.com.
NS1	IN	A	192.168.0.10
NS1	IN	A	192.168.0.11
;
A	IN	A	192.168.1.10

TEST PROCEDURE

        This test sequence is following.

    DNS Client1 (TN)                       DNS Server1 (NUT)
        |                                      |
        |------------------------------------->|
        |   1. Send standard query             |
        |   *Destination address=192.168.0.10  |
        |       QNAME=A.example.com            |
        |       QTYPE=A                        |
        |                                      |
        |<-------------------------------------|
        |   2. Standard query response         |
        |   *Source address=192.168.0.10       |
        |       A=192.168.1.10                 |
        |                                      |
        |------------------------------------->|
        |   3. Send standard query             |
        |   *Destination address=192.168.0.11  |
        |       QNAME=A.example.com            |
        |       QTYPE=A                        |
        |                                      |
        |<-------------------------------------|
        |   4. Standard query response         |
        |   *Source address=192.168.0.11       |
        |       A=192.168.1.10                 |
        |                                      |
        |                                      |
        v                                      v

        1. TN send standard query QNAME=A.example.com, QTYPE=A to NUT that destination address=192.168.0.10.
        2. NUT reply query response w/ A=192.168.1.10 to TN that source address=192.168.0.10(Judgment *2)
        3. TN send standard query QNAME=A.example.com, QTYPE=A to NUT that destination address=192.168.0.11.
        4. NUT reply query response w/ A=192.168.1.10 to TN that source address=192.168.0.11(Judgment *4)

Packet Description

1st packet.

Standard query from DNS Client1 (TN) to Server1 (NUT)
IP Header	Source Address	CL1_NETZ
IP Header	Destination Address	NUT_NETZ
UDP Header	Src Port	2000
UDP Header	Dst Port	53
DNS Header	ID	0x1000
	QR	0
	OPCODE	0
	AA	0
	TC	0
	RD	1
	RA	0
	Z	0
	RCODE	0
	QDCOUNT	1
	ANCOUNT	0
	NSCOUNT	0
	ARCOUNT	0
DNS Question section	QNAME	A.example.com
	QTYPE	A (0x0001)
	QCLASS	IN (0x0001)

2nd packet.

Standard query response from DNS Server1 (NUT) to Client1 (TN)
IP Header	Source Address	NUT_NETZ
IP Header	Destination Address	CL1_NETZ
UDP Header	Src Port	53
UDP Header	Dst Port	2000
DNS Header	ID	0x1000
	QR	1
	OPCODE	0
	AA	1
	TC	0
	RD	1
	RA	ANY
	Z	0
	RCODE	0
	QDCOUNT	1
	ANCOUNT	1
	NSCOUNT	1
	ARCOUNT	2
DNS Question section	QNAME	A.example.com
	QTYPE	A (0x0001)
	QCLASS	IN (0x0001)
DNS Answer section	NAME	A.example.com (Pointer 0xC00C)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.1.10
DNS Authority section	NAME	example.com (Pointer 0xC00E)
	TYPE	NS (0x0002)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	6
	NSDNAME	NS1.example.com (NS1 + Pointer 0xC00E)
DNS Additional section	NAME	NS1.example.com (Pointer 0xC03B)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.0.10
DNS Additional section	NAME	NS1.example.com (Pointer 0xC03B)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.0.11

3rd packet.

Standard query from DNS Client1 (TN) to Server1 (NUT)
IP Header	Source Address	CL1_NET
IP Header	Destination Address	NUT_NETZ2
UDP Header	Src Port	2000
UDP Header	Dst Port	53
DNS Header	ID	0x1001
	QR	0
	OPCODE	0
	AA	0
	TC	0
	RD	1
	RA	0
	Z	0
	RCODE	0
	QDCOUNT	1
	ANCOUNT	0
	NSCOUNT	0
	ARCOUNT	0
DNS Question section	QNAME	A.example.com
	QTYPE	A (0x0001)
	QCLASS	IN (0x0001)

4th packet.

Standard query response from DNS Server1 (NUT) to Client1 (TN)
IP Header	Source Address	NUT_NETZ2
IP Header	Destination Address	CL1_NETZ
UDP Header	Src Port	53
UDP Header	Dst Port	2000
DNS Header	ID	0x1001
	QR	1
	OPCODE	0
	AA	1
	TC	0
	RD	1
	RA	ANY
	Z	0
	RCODE	0
	QDCOUNT	1
	ANCOUNT	1
	NSCOUNT	1
	ARCOUNT	2
DNS Question section	QNAME	A.example.com
	QTYPE	A (0x0001)
	QCLASS	IN (0x0001)
DNS Answer section	NAME	A.example.com (Pointer 0xC00C)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.1.10
DNS Authority section	NAME	example.com (Pointer 0xC00E)
	TYPE	NS (0x0002)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	6
	NSDNAME	NS1.example.com (NS1 + Pointer 0xC00E)
DNS Additional section	NAME	NS1.example.com (Pointer 0xC03B)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.0.11
DNS Additional section	NAME	NS1.example.com (Pointer 0xC03B)
	TYPE	A (0x0001)
	CLASS	IN (0x0001)
	TTL	1 day (86400)
	RDLENGTH	4
	ADDRESS	192.168.0.10

Exp.

NUT_NETZ	DNS Server1's (NUT) Net-z address
NUT_NETZ2	DNS Server1's (NUT) another Net-z address
CL1_NETZ	DNS Client1's (TN) Net-z address

JUDGMENT

        2. Received standard query response w/ A=192.168.1.10 that source address=192.168.0.10.
        4. Received standard query response w/ A=192.168.1.10 that source address=192.168.0.11.

TERMINATION

        None

REFERENCE

        RFC2181 Clarifications to the DNS Specification
        4.1. UDP Source Address Selection