TCP/IP Security
CHRIS CHAMBERS, JUSTIN DOLSKE, and JAYARAMAN IYER
Department of Computer and Information Science, Ohio State University, Columbus, Ohio 43210
The TCP/IP protocols, the basis for today's Internet, lack even the most basic mechanisms for security, such as authentication or encryption. As usage of the Internet and TCP/IP protocols increases, their lack of built-in security has become more and more problematic. This paper describes a variety of basic flaws in TCP/IP protocols and their implementations, and discusses solutions and work-arounds to these problems. Also covered is the new IPv6, the next-generation Internet protocol that, among other goals, seeks to fix many of the current flaws in the current Internet IPv4 protocol. Security in protocols and applications not essential to TCP/IP (such as HTTP, FTP, and SMTP) are not discussed in this paper.
Introduction
In the early 1980's, specifications were finished for the TCP and IP protocols. These two protocols could be considered the most important in the world today - they are the basis of the Internet. Over the past decade, the Internet has grown from a small network connecting a small community of researchers to its present state - a gigantic global network connecting people of all types. The huge success of the Internet has, for the most part, been quite beneficial. The Internet has evolved from a specialized project to a general-purpose tool. However, the growth of the Internet has created problems with security. The TCP and IP protocols were designed when the Internet was small, and users generally trusted each other. The protocols lack many features that are desirable or needed on an insecure network. In this paper, we present a number of problems that arise with using TCP/IP on today's network, solutions or work-arounds for these problems, and how the protocols for tomorrow's Internet, such as IPv6, will help eliminate these problems.
1. Introduction to TCP/IP
TCP/IP is the backbone of the internet today. Comprised of two protocols, TCP and IP, the TCP/IP protocol suite is one of the most widely used. We present a brief introduction to the two protocols. For a detailed discussion of the two protocols we refer the reader to the RFC's for IP [RFC 791], and TCP [RFC 793].
1.1. Internet Protocol
The Internet Protocol (or IP as it generally known), is the network layer of the Internet. IP provides a connection-less service. The job of IP is to route and send a packet to the packet's destination. IP provides no guarantee whatsoever, for the packets it tries to deliver. The IP packets are usually termed datagrams. The datagrams go through a series of routers before they reach the destination. At each node that the datagram passes through, the node determines the next hop for the datagram and routes it to the next hop. Since the network is dynamic, it is possible that two datagrams from the same source take different paths to make it to the destination. Since the network has variable delays, it is not guaranteed that the datagrams will be received in sequence. IP only tries for a best-effort delivery. It does not take care of lost packets; this is left to the higher layer protocols. There is no state maintained between two datagrams; in other words, IP is connection-less.
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