Difference between Global Proxy and PAC Proxy Server

In the online world, we often encounter situations where we need to hide our real IP address, such as accessing restricted websites or improving network security. In order to achieve this, there are two common types of proxies: global proxies and PAC (Proxy Auto-Config) proxy servers. Although they both provide proxy functionality, they have different characteristics in the way they are implemented and the scenarios in which they are used.

global proxy

A global proxy is a way to forward all network traffic through a proxy server. When we configure a global proxy, all programs running on our computer (such as browsers, download tools, chat software, etc.) communicate with the Internet through a proxy server. This approach is very effective for situations where you need to hide your real IP address because it ensures that all network connections go through the proxy server. However, it has some shortcomings.

Global proxies have an obvious disadvantage, which is that they can have an impact on the performance of your computer. Since all traffic needs to pass through the proxy server, in case of high load on the proxy server, the network connection may become slow or even lead to network instability. In addition, our privacy is also at risk since all application data is transmitted through the proxy server.

PAC Proxy Server

PAC proxy servers provide a more flexible approach to proxying than global proxies.PAC proxy servers work by determining whether a proxy or a direct connection should be used, based on specific rules that direct requests to the appropriate link. These rules are usually defined through a PAC script.

Specifically, we can write a series of conditional statements in a PAC script to determine whether a proxy or a direct connection should be used based on different URLs or other rules.PAC scripts can be quickly and flexibly modified as needed without modifying global proxy settings, and can be personalized for different applications or specific access requirements.

PAC script example:

function FindProxyForURL(url, host) {
// The URL and host for which the proxy is needed
if (shExpMatch(url, "*example.com*") || shExpMatch(host, "example.com")) {
return "PROXY proxy.example.com:8080";
}

// URLs and hosts that don't need to use proxies
if (shExpMatch(url, "*.local") || isInNet(dnsResolve(host), "10.0.0.0", "255.0.0.0")) {
return "DIRECT";
}

// Use proxy by default
return "PROXY proxy.example.com:8080";
}

In the above example, if the URL contains "example.com" or the host is "example.com", then use the proxy server "proxy.example. com:8080″; if the URL ends with ".local" or the IP address of the host is in the "10.0.0.0/8″ network segment, then the connection is made directly; for other cases, the proxy server is used by default.

summarize

Global Proxy and PAC Proxy Server are both common proxy methods, which have different characteristics and applicable scenarios. Global proxy can effectively hide the real IP address by forwarding all network traffic to a proxy server, but it may have an impact on computer performance. The PAC proxy server, on the other hand, provides a more flexible proxy method by using PAC scripts to determine whether to use a proxy or direct connection based on specific rules. It is relatively easier to configure and manage and can meet the individual needs of different applications. When choosing a proxy method, we can choose whether to use Global Proxy or PAC Proxy Server according to specific needs.