IPSec Overhead in Wireline and Wireless Networks for Web and Email Applications

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Date

2001-11-29

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Virginia Tech

Abstract

This research focuses on developing a set of secure communication network testbeds and using them to measure the overhead of IP Security (IPSec) for email and web applications. The network testbeds are implemented using both wireline and wireless technologies. The testing involves a combination of authentication algorithms such as Hashed Message Authentication Code-Message Digest 5 (HMAC-MD5) and Hashed Message Authentication Code-Secure Hash Algorithm 1 (HMAC-SHA1), implemented through different authentication protocols such as ESP and AH, and used in conjunction with the Triple Digital Encryption Standard (3DES). The research examines the overhead using no encryption and no authentication, authentication and no encryption, and authentication and encryption. A variety of different sizes of compressed and uncompressed files, are considered when measuring the overhead.

The testbed realizes security using IPSec to secure the connection between different nodes. The email protocol that is used is the Simple Mail Transfer Protocol (SMTP) and the web protocol considered is the Hyper Text Transfer Protocol (HTTP). The key metrics considered are the network load in bytes, the number of packets, and the transfer time.

This research emphasizes the importance of using HTTP to access files than using SMTP. Use of HTTP requires fewer packets, lower network loads, and lower transfer times than SMTP. It is demonstrated that this difference, which occurs regardless of security, is magnified by the use of authentication and encryption. The results also indicate the value of using compressed files for file transfers. Compressed and uncompressed files require the same transfer time, network load and number of packets since FreeS/WAN IPSec does not carry any form of compression on the data before passing it to the data link layer. Both authentication algorithms, HMAC-MD5 and HMAC- SHA1, result in about the same network load and number of packets. However, HMAC-SHA1 results in a higher transfer time than HMAC-MD5 because of SHA1's higher computational requirements. ESP authentication and ESP encryption reduce the network load for small files only, compared to ESP encryption and AH authentication. ESP authentication could not be compared with AH authentication, since the FreeS/WAN IPSec implementation used in the study does not support ESP authentication without using encryption. In a wireless environment, using IPSec does not increase the network load and the number of transactions, when compared to a wireline environment. Also, the effect of security on transfer time is higher compared to a wireline environment, even though that increase is overshadowed by the high transfer time percentage increase due to the wireless medium.

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Keywords

ESP, MD5, 3DES, IP Security, AH, SHA1

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