When you think initially about access control to a standard proxy one of the most obvious options is tradtional user name and password. Indeed access control by user authentication is one of the most popular methods if only because it’s generally one of the simplest to implement. Not only does it use readily available information for authentication it will also fit neatly in with most corporate networks which generally run on a Windows or Linux platforms. All common OS’s support user authentication as standard and normally using a variety of protocols.

Access control based on the username and group is a commonly deployed feature of proxies. It requires users to authenticate themselves to the proxy server before allowing the request to pass. This way, the proxy can associ- ate a user identity with the request and apply different restrictions based on the user. The proxy will also log the username in its access log, allowing logs to be analyzed for user-specific statistics, such as how much bandwidth was consumed by each user. This can be vital in the world of high traffic multimedia applications and a few users using your Remote access server as a handy BBC VPN service can bring a network to it’s knees.

Authentication There are several methods of authentication. With HTTP, We/9 servers support the Basic authentication, and sometimes also the Digest authentication (see HTTP Authentication on page 54). With HTTPS—— or rather, with any SSL-enhanced protocol—certificate-based authentication is also possible. However, current proxy servers and clients do not yet support HTTPS communication to proxies and are therefore unable to perform certificate-based authentication.

This shortcoming will surely be resolved soon. Groups Most proxy servers provide a feature for grouping a set of users under a single group name. This allows easy administration of large numbers of users by allowing logical groups such as admin, engineering, marketing, sales, and so on. It will also be useful in multinational organisations where individuals may need to authenticate in different countries and using global user accounts and groups. So if a UK based salesman was travelling in continental Europe he could use his UK account to access a French proxy and use local resources.

ACCESS CONTROL BY CLIENT HOST ADDRESS An almost always used access control feature is limiting requests based on the source host address. This restriction may be applied by the IP address of the incoming request, or the name of the requesting host. IP address restrictions can often be specified with wildcards as entire network sub- nets, such as 112.113.123 . * Similarly, wildcards can be used to specify entire domains: * . yoruwebsite.com

Access control based on the requesting host address should always be performed to limit the source of requests to the intended user base.

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