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

与全局代理相比，PAC代理服务器则提供了一种更加灵活的代理方式。PAC代理服务器的工作原理是：根据特定的规则判断应该使用代理还是，将请求定向到相应的链路上。这些规则通常通过一个PAC脚本来定义。

具体来说，我们可以在PAC脚本中编写一系列条件语句，根据不同的URL或其他规则来决定应该使用代理还是。PAC脚本可以根据需要快速而灵活地修改，而不需要修改全局代理设置，并且可以针对不同的应用程序或特定的访问要求进行个性化的配置。

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

全局代理和PAC代理服务器都是常见的代理方式，它们有着不同的特点和适用场景。全局代理通过将所有网络流量转发到代理服务器，可以有效隐藏真实IP地址，但可能对电脑性能产生影响。而PAC代理服务器则提供了更加灵活的代理方式，通过PAC脚本根据特定规则判断是否使用代理或。它相对而言更加易于配置和管理，可以满足不同应用程序的个性化需求。在选择代理方式时，我们可以根据具体需求来选择使用全局代理还是PAC代理服务器。

Difference between Global Proxy and PAC Proxy Server