如果默认情况下防火墙不接受传入连接，那么p2p网络如何工作? [英] If firewalls don't accept incoming connections by default how do p2p networks work?

问题描述

如果默认情况下防火墙阻止所有传入连接，则p2p技术如何工作?像洪流一样，您如何连接到共享文件的每个人并从文件中获取信息?它通过中继服务器还是其他?

If firewalls block all incoming connections by default how do p2p technologies work? Like torrents, how do you connect to everyone who shares a file and get the information from them? Does it go through a relay server or something?

推荐答案

我不了解BitTorrent的所有知识，因为我了解通用的P2P连接技术.通常，P2P网络中的客户端在公共信令服务器(例如SIP，XMPP，跟踪服务器，网站)上会合，以交换IP地址，其他元数据和消息以引导直接连接.然后，使用以下任何一种以下技术来进行通信会话:

I'm not up on everything about BitTorrent, as I am about general P2P connectivity techniques. Typically clients in a P2P network rendezvous on a common signaling server (e.g. SIP, XMPP, tracking server, web site) to exchange IP addresses,other meta data, and messages to bootstrap direct connections. Then use any of the following techniques below to get a communications session going:

• 双方都试图同时相互连接-以防万一一方不能接受传入的连接，但允许建立出站连接.防火墙方案就是这种情况.

• Both sides attempt to connect to each other simultaneously - in case one side can't accept incoming connections, but is allowed to make outbound connections. Such is the case for the firewall scenario.

孔打孔(与上面结合使用).中继本身并不是必需的，但是当两个对等点都位于难以穿越的网络设备之后时，中继确实有助于确保连接性.同时有 UDP打孔和此处.

Hole punching (used in conjunction with above). Relays are not required per se, but do help insure connectivity when both peers are behind network devices that are difficult to traverse. There's both UDP Hole Punching as well as TCP Hole Punching techniques. More info here.

中继(包括 TURN服务器)可以在直接时部署到P2P网络中连接是不可能的.您最喜欢的所有视频通话应用程序都针对这些情况部署中继，但是会尽力使对等方直接连接，从而避免中继的成本.

Relays, including TURN servers, can be deployed into a P2P network when direct connectivity is not possible. All your favorite video call applications deploy relays for these scenarios, but do their best to get peers directly connected to avoid the cost of relaying.

以下主题的必应:STUN，TURN，ICE(交互式连接建立)，libjingle，pjnath，libnice.

Bing for the following topics: STUN, TURN, ICE (Interactive Connectivity Establishment), libjingle, pjnath, libnice.

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