Networks today are often connected to the Internet to allow employees to study using the World Wide Web (WWW). These networks are typically protected from external access or attack via network “firewalls.”
Firewalls are special packet routers that allow or deny traffic (commonly TCP/IP traffic) based on various criteria. Many organizations utilize network firewalls to control internal employee access to external Internet resources and regulate external access to intranets. Nations without controlled borders cannot ensure the security and safety of their citizens, nor can they prevent piracy and theft.
When retrieving a URL, a browser uses the hostname component to convert the name to an IP address. The client establishes an HTTP session against that address and asks the server for the URL. When using a proxy cache, the transaction is not significantly changed.
The URL request is routed to the proxy cache by the client after opening an HTTP session with it. In this article, we will learn about Proxy Servers and Web Caching.
Proxy Servers
Order to completely break the network connection between internal and external hosts. Packet filtering firewalls accept or drop packets based on their source and destination address or ports. Packet-filtering firewalls must usually be used with other firewall components to provide more challenging security.
The circuit-level firewall relays TCP connections. The caller connects to a TCP port on the gateway, which connects to some destination on the other side. The third type of firewall is the application layer firewall, in which special-purpose code is used for each desired application. These firewalls make it easy to control all incoming and outgoing network traffic. Most firewalls perform encrypted authentication.
This allows users on the public network to prove their identity to the firewall to gain access to the private network from external locations. Some firewalls also provide additional subscription-based services that are not strictly related to security but which many users will find helpful for the features such as virus scanning and content filtering.
Why do we need Proxy Servers?
As hacking attacks and cyber crime incidents continue to increase, many companies are highly interested in getting insights into how their enterprises should secure corporate networks.
The firewall is a healthy and growing segment in the IT market. The Internet is now a critical part of corporate networks, and Internet downtime can cause lost productivity and revenue. The explosion of e-commerce and the growth of the mobile workforce have significantly increased security challenges for enterprises.
Firewall vendors continue to add new features to their products as they compete to solve the increasingly complex problems of securing connections to the Internet, Intranets, and Extranets.
Network Security has become a primary concern worldwide with the highly vulnerable Internet. With more and more people depending on the Internet for their day-to-day activities, security breaches can be highly costly to the concerned party. Statistics show that there has been a surge in the number of security breaches in recent years.
Benefits of Proxy Servers
The process of request regeneration and the fact of a proxy's location between the external and internal networks provide several security advantages:
The major security feature of proxy servers is client hiding. Like Network Address Translation, proxy servers can make an entire internal network appear to be a single machine from the Internet because only a single device passes requests onto the Internet.
URL blocking allows administrators to disallow the provision of certain websites based on their URLs. In theory, this will keep your employees from viewing sites you don't want them to have access to. This function is easy to implement.
Because proxies retransmit all protocol payloads and are protocol specific, the proxy service can search the payload for suspicious content. This means you can configure your HTTP proxy service to strip out ActiveX controls, Java applets, or large images if they present a security problem.
Consistency checking refers to checking the content of a protocol to be sure it makes sense for that protocol. Consistency checking ensures that specifically malformed types of content can't be used to exploit a security weakness in your internal network.
Transport layer packets need not be routed because the request is completely regenerated. This eliminates transport layer exploits like source routing, fragmentation, and denial-of-service attacks. By eliminating routing, you can also ensure that any protocol for which you have not established a proxy service cannot be passed to the public network.
The final security advantage of proxies is the logging and alerting facilities they provide. Proxies ensure that all content flows through a single point, which gives you a checkpoint for network data. Most proxy software will log the usage characteristics of the proxy by a user and can be configured to retain a log of sites they visit.
Web Caching
Web browsing dominates today’s Internet. More than two-thirds of the traffic on the Internet today is generated by the Web. In looking at how to improve the quality of service delivered by the Internet, a very productive way to start is by examining the performance of Web transactions.
Here, Web caching can be valuable in improving service quality for an extensive range of Internet users. There are two types of Web caches—a browser cache and a proxy cache. A browser cache is part of all popular Web browsers.
The browser keeps a local copy of all recently displayed pages, and when the user returns to one of these pages, the local copy is reused. By contrast, a proxy cache is a shared network device that can undertake Web transactions on behalf of a client, and, like the browser, the proxy cache stores the content.
Subsequent requests for this content by this or any other client of the cache will trigger the cache to deliver the locally stored copy, avoiding a repeat of the download from the original content source.
Why do we need Web Caching?
The cache coherency problem is a separate issue because it requires a special request to the original server to determine the status of the actual document.
Although it is suggested that the HEAD request is sufficient for this purpose, it is found that it needs to be more efficient for a caching mechanism (because of the server overhead from connecting twice and locating the file twice).
The solution is to implement a conditional GET request that includes a date to be checked against the last-modified date of the information object. Some last modification date headers, similar to the current Content-type, Authorization, etc, followed the standard GET request.
Benefits of Web Caching
The same benefits of improved performance and reduced outbound traffic loads can be realized for World Wide Web traffic through the deployment of Web caches.
The client request is passed through a cache agent, which requests the original source as a proxy for the client. The response of the server is retained in a local cache, and a copy of The Internet Protocol Journal is passed to the client. Suppose the same request is passed to the cache agent soon after the original request was serviced. In that case, the response can be generated from the cache without further referencing the original source.
Measurements of ISP traffic profiles indicate that some 70 percent of a typical ISP's traffic is Web-based traffic. An analysis of Web requests suggests that the standard level of similarity of requests (for the same object as one previously requested) can be as high as 50 percent of all Web-based traffic.
The average size of a Web transaction is 16 data packets within the TCP flow. Within a TCP slow-start flow-control process, the first cycle will transmit one packet and wait for an ACK.
A slightly different analysis is possible when comparing the performance of a cache configured at the headend of a cable-IP system versus the performance of direct access. The difference in latency, in this case, is due to both the closer positioning of the cache to the user and the significantly increased effective bandwidth from the cache to the user.
With cached content in operation, the cached-content server no longer has an accurate picture of the number of times an item of content is viewed and by whom. The server cannot authenticate the client or deliver any information based on the client's supposed identity.
There are two hit-rate measures, a page hit rate and a byte hit rate. A page hit rate measures the proportion of individual HTTP requests that can be served from the cache, irrespective of the page size. A byte hit rate measures the ratio of the bytes delivered from the cache in hits against the number of bytes in misses.
The trade-off with caching is balancing the cost of carriage capacity, both in terms of the monetary cost of the carriage and the performance cost of the transaction time of the application, against the cost of the use of caching.
Frequently Asked Questions
What is a Classical Proxy?
Classical proxy is commonly used. All packets are addressed to the proxy, and the proxy directs the packets. There are two sessions established, a client-proxy and a proxy-server. The client uses the proxy's address, which redirects it. Thus, a classical proxy hides the IP addresses of all machines on the network.
What is HTTP?
The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object-oriented protocol that can be used for many tasks, such as name servers and distributed object management systems, through extension of its request methods.
What is Transparent Caching?
The ISP can also use a cache for all Web traffic without the explicit configuration of the identity of the proxy cache in the user’s browser. Irrespective of precisely how this setup is engineered, and there are numerous ways of planning it, this technique is termed transparent caching.
Conclusion
In this article, we learn about Proxy Servers and Web Caching. We also know about Proxy Servers and also Web Caching. We concluded the article by discussing the definition, uses, and Benefits of Proxy Servers and Web Caching.
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