Lauri Virtanen

Supervisor: Professor Raimo Kantola

Instructor: Lic.Sc.(Tech.) Nicklas Beijar

Faculty of Electronics, Communications and Automation

Department of Communications and Networking

October 29th, 2009

Agenda• Backround & Objectives

• Network Address Translation (NAT)

• Domain Name System (DNS)

• Customer Edge Switching (CES) Concept

• CES Prototype

• Evaluation

• Conclusions

Backround & Objectives• The growing of Internet has generated problems

• The run out of IPv4 addresses

• Weak deployment of IPv6 addressing

• Oversizing routing tables

• Reachability problem

• A new architecture model needed to solve the current problems

Network Address Translation (NAT)• An edge device that relays packets

• Changes address and port information from outgoing and

incoming packets

• Traffic originates from inside to outside direction

• Inbound connection not possible -> reachability problem

Domain Name System (DNS)• Main use is solving domain names to IP addresses

• In DNS, data is stored in resource records (RR)

• E.g. A-type RR: domain_name _Host_A <-> IPv4_address_Host_A

Customer Edge Switching (CES) Concept• CES is a model for the future Internet

• Idea to solve the reachability problem

• Idea to prevent IPv4 addresses from extinction by using them

privately

• Removes the need for IPv6 and also increases security

• CES is aimed to be implemented with as little modification as

necessary in the existing equipments

• Modifications allowed in DNS and NAT, hosts remain the same

• Aims at dividing the ownership of network into reasonable

pieces: Trust domains (corporate networks, operator networks)

CES architecture:

• Routing independent in every Trust domain

• Network elements: host, CES, PE, DNS

• Identities are known only in its respective private network

• E.g. Identity of Host X is kept in its home CES device (CES

X) and also in the DNS

CES Network Elements Explained• Host:

• Basic IPv4 stacked

• CES:

• NAT extension containing its features: mappings and tables

• Contains information of all the registered hosts (HRL)

• Address pool of IPv4 addresses

• Hash calculating algorithm

• DNS:

• Needs a new resource record (RR) type:

• domain_name_Host_X = Address_CES_X + hash_Host_X

• E.g. host_x.foobar = MAC_CES_X + 1234

CES Prototype

• The implemented prototype differs slightly from CES concept

• No PE devices

• Prototype built on virtual PCs running Linux/Debian

• Programming done with Python

• DNS executed with DNSPython toolkit

• Packet generating, sending and receiving done with Scapy

Network Diagram:

• 2 Hosts, 2 CES devices and DNS

• IP routing (layer 3) in customer networks

• Ethernet (layer 2) based routing in public network

Evaluation• CES can be implemented with only a few modifications in the

existing infrastructure

• Only NAT and DNS need modifications

• Hosts are still IPv4 stacked computers

• CES works with most of the common protocols

• According to testing, CES works with TCP, UDP, ICMP, HTTP

and SSH

• Still lacks compatibility with FTP and SIP

Test Results

Program in Host A Program in Host B Protocols tested Working

Ping client Ping server ICMP YESTelnet client Telnet server TCP YESLynx web browser Abyss web server HTTP YESIceweasel web browser Abyss web server HTTP YES

SSH client SSH server SSH YESFTP client Pure-FTPd (server) FTP NoTwinkle (client) Twinkle (client) SIP No

• FTP and SIP fail as private addresses are placed in payload fields

• FTP and SIP does not work with two NATs (or CESs)

• Packet modification in CES could solve this

Conclusions• The prototype proves the functioning of CES concept

• CES solves the reachability problem

• CES reuses IPv4 addresses effectively

• CES excludes the need for IPv6 addresses

• CES enhances security

• No modification needed in end-hosts

Future Research• Connecting CES prototype to other networks

• Modification of CES prototype

• Designing and choosing algorithms for calculating IDs

Thank You!