Internet Protocols: Versions 4 and 6 Analysis and Comparison of IPv4 and IPv6

Internet Protocols: Versions 4 and 6

Analysis and Comparison of IPv4 and IPv6

The rate at which internet is being used is rapidly growing and Internet existed due to communicating nodes with each other. Development of the internet goes on as new users are joining to the structure. Thus, in such a large structure, two nodes can communicate if they find each other. Different addressing protocols are developed to achieve the communication. The principal set of rules of communication for relaying datagrams over network boundaries is called the Internet Protocol. Its primary aim is to deliver packets to the destination hosts from the source host through the protocol addresses in the packet header. There are some historical versions of the IP but the most dominant one is the IPv4 (Internet Protocol version 4). The earlier versions (0-3) were development versions that were used between 1977-1979. Another version (IPv5) was later developed, but this was used by the Internet Stream Protocol (an experimental stream protocol). Hence, the heir of IPv4 is the Internet Protocol version6 (IPv6). This paper aims at analysing and comparing both IPv4 and IPv6 based on their attributes and functionalities.

Keywords- IPv4; IPv6; IP threats; vulnerability; exploits; security comparison; IP attacks.

I.                    INTRODUCTION

The Internet Protocol version 4 (IPv4) has been the prevailing Internet Protocol standard and has been in existence since the 1970s. Some of the limitations of IPv4 are the limited IP address space and lack of security amongst many well-known limitations of this version. IPv4 utilizes a 32-bit IP address field (4.3 x 10⁹ addresses) in which the available address spaces are swiftly being exhausted. The option field which allows the hosts to send security and handling is the only security feature available in IPv4. The need thus arose for the improvement of this version of Internet Protocol and led to the existence of Internet Protocol version 6 (IPv6) which can be dated back to 1995. The Internet Engineering Task Force (IETF) is thereby seriously working on the IPv6 specifications so as to cater for the limitations that are exhibited by IPv4. They are also working on the ease of performance, network management issues and the number of performance. Hence, IPv6 is referred to as the Next Generation Internet Protocol (IPng).

II             INTERNET PROTOCOL VERSION 4 (IPv4)

The fourth version in the development and the first version of the Internet Protocol to be widely deployed, Internet Protocol version 4 (IPv4) is a connectionless protocol for use on packet-switched networks; it uses 32-bits (4 byte) addresses; its exhaustion occurred in February 3, 2011 around the Asia Pacific region; IPv4 reserves special address blocks for private networks and multicast addresses.

A.      The IPv4 Packet Header

In IPv4 the fields of the Internet Protocol header are a small set, as shown in Figure 1. An IP packet header exposes the protocol Version, Header Length (IHL), Total Length of the IP packet, packet Fragmentation Offset, and Type of Service fields, a hop counter (Time to Live field), a Header Checksum field, and the Source and Destination Address fields. In practice, the Type of Service field is unused, and the Length and Checksum fields have information that is also contained in the data link frame header. What is left is the protocol Version field, packet length (Total Length field), the Fragmentation Offset field, a hop counter, and the Source and Destination Address fields. Of these fields, the Packet Length, Fragmentation Offset, hop counter, and Destination Address are the fields used by the network to forward the packet to its ultimate destination.[1]

B.      IPv4 Address Representation

The addresses may be displayed in any notation that expresses a 32-bit integer value, however for human convenience, they are often times written in the dot-decimal notation consisting of four octets of the address expressed individually in decimal and separated by periods.

Table 1 - Several representation formats of IPv4.

III           INTERNET PROTOCOL VERSION 6 (IPv6)

With the provision of identification and location system for computers on networks, Internet Protocol Version 6 (IPv6) is the latest revision of the Internet Protocol (IP). It was developed to tackle the long-anticipated problem of IPv4 exhaustion. Even though it was designed to replace IPv4, as of September 2013, the percentage of users using Google services over IPv6 surpassed 2% for the first time. [2]; IPv6 uses 128-bit address which is 7.9 x 10²⁸ times as many as IPv4. Traffic exchange between the two networks requires transition technologies or translator gateways such as tunnelling protocols 6to4, 6in4, and Teredo.

A.      IPv6 Packet Header

In IPv6 the minimal approach was further exercised with the removal of the Fragmentation Control fields and the Checksum fields (Figure 2). Arguably, the Traffic Class and Flow Label are unused, leaving only the Protocol Version, Payload Length, a Hop Counter, and the source and destination addresses exposed to the network. In IPv6 the minimal network-level information is now reduced to the packet length, the hop counter, and the destination address. [1]

B.                  IPv6 Address Representation

Eight groups of sixteen bits each represents the 128bits of an IPv6 with each group written as 4 hexadecimal digits and are separated by colons (:). Some rules can be applied to IPv6 for convenience to shorter notations. These includes the removal of one or more leading zeros from any group of hexadecimal digits, and the replacement of consecutive sections of zeroes with a double colon (::).

 IV          COMPARISON OF IPv4 AND IPv6

                Due to the significant difference between the headers of the IPv4 packets and IPv6 packets, both protocols are not interoperable. Thus we compare some of their characteristics.

A.      ADDRESS SPACE

IPv6 is more advantageous over IPv4 with the use of 128bit address compared with the 32bit in IPv4. The longer addresses in IPv6 facilitate allocation of addresses, allow execution of distinct addressing features and enable effectual route aggregation.

B.      MOBILITY

Mobile IPv6 does not support triangular routing (a form of routing that sends a packet to a proxy system before transmission to the intended destination), thus is as efficient as the native IPv6 unlike mobile IPv4. Also IPv6 routers allow the movement of all subnets to a new router connection point without renumbering.

C.      MULTICATING

Multicasting is the transmission of packets in a single send operation to multiple destinations. It is part of a basic specification in IPv6 whereas it is an optional feature in IPv4.

D.      JUMBOGRAMS

IPv6 nodes optionally handle packets as large as 4 294 967 295 (2³² – 1) octets of payloads which is referred to as Jumbograms whereas IPv4 limits packets to 65 535 (2¹⁶ – 1) octets of payloads. Jumbograms usage improves the performance over high Maximum Transmission Units (MTU) links.

 V             DIFFERENCES BETWEEN IPv4 AND IPv6

Table 2 – Differences between IPv4 and IPv6.

SOURCE: Adapted from Wong .W, Electronic Design.

The table above highlights the differences between IPv4 and IPv6. Brief explanation of some of the characteristics are thus below;

1. ADDRESS: Up to 2128 IP addresses can be defined with the increased IP address size in IPv6 instead of allowing for only 32-bit as the case is in IPv4.
2. PACKET HEADER: IPv6 header cannot vary in size unlike IPv4; the header contains exactly 8 fields which is always exactly 40 bytes.
3. AUTO CONFIGURATION: This is an important feature in IPv6; it introduces a simplified stateless auto configuration procedure whereby based on local information, a node can configure its IP address without contacting a server.
4. QUALITY OF SERVICE: For both differentiated and integrated services, IPv6 packet header has fields that enhance the support for QoS; it includes ‘labelled flows’ in its specifications to deliver better support for real-time traffic.
5. IPsec: It is a suite of protocols that provide network layer encryption and authentication for IP based networks. Even though it can be found in IPv4 implementations, it is optional. On the other hand, IPsec is a requirement in IPv6 implementation.

VI           SECURITY THREATS SIMILAR IN           

 IPv4 AND IPv6

The IPv6 is not perfect because it is vulnerable to P2P-based warm attack, this kind of attack simply locate host in a local network of IPv6 internet that means routing protocols, neighbour discovery caches, host configuration and log files could be exploited to identify additional hosts on the network[4].

The challenges in IPv6 are also similar to that of IPv4 in terms of vulnerability. Some types of attack have not changed even after the deployment of IPv6 protocols despite the security measures implemented on the IPv6.

A.            The Sniffing attacks- This attack involves capturing of transmitted data over a network. Thus it can be avoided by a proper use of IPsec security architecture which is used as an option in IPv4 and obligation in IPv6. [3]

B.            Application layer attacks-These types of attacks today are the most common attacks today such as buffer overflow and application attacks by the use of warms and viruses. Unfortunately transition from IPv4 to IPv6 will not prevent such attacks since it occurs at the application layer of the OSI model. [3]

C.            Flooding attacks-This type of attack is responsible for the DOS (Denial of service attack) and the DDOS (Distributed denial of service attacks), where a router is flooded with requests until it cannot process any longer then the network becomes unavailable. [3]

D.            Man-in-the-Middle attacks (MITM)-The IPv4 and IPv6 headers have no security mechanism themselves, each protocol relies on the IPsec protocol suite for security. In this fashion IPv6 falls prey to the same security risk posed by MITM attacking the IPsec protocol suite. [3]

VII          CONCLUSION

Since the transition from ipv4 to ipv6 protocols will be gradual, for a certain period both of them coexist. To ensure smooth transition new transition mechanisms are developed. The most important transition mechanisms are tunnelling and dual-stack (supporting both ipv4 and ipv6 protocols).

Although IPv6 offers better security, larger address space and the use of encrypted communication. “The protocol also raises new security challenges. For an improved protection in ipv6 networks it is recommended to implement security mechanisms such as firewalls and Intrusion detection systems (IDS) all unneeded services should be filtered at the firewall. [3]”

Nevertheless security of ipv4 protocol and ipv6 network can still be improved with time.

REFERENCES

[1] The Internet Protocol Journal Vol.16, No.2, (June 2013).

[2] Roberts Phil (24 September 2013). “IPv6 Deployment Hits 2%, Keeps Growing. Internet Society. Retrieved 27 September 2013.

[3] Emre Durdagi, Ali Buldu (January, 2010) – IPv4 and IPv6 security and threat comparisons.

[4] Wei Yang, Cheng-dong Li, Gui-ran Chang, Yu Yao, Xiao-meng Shen (2011). The Effect of P2P-based Worm Propagation in an IPv6 Internet.