这是我所在组织的一位软件工程师提出的问题。我感兴趣的是最广义的定义。
当前回答
这些是基本的网络概念,所以我将以一种简单而全面的方式详细解释它们。
插座就像电话(即端到端通信设备) IP就像你的电话号码(即你的插座地址) 端口就像您想要与之交谈的人(即您想从该地址订购的服务) 插座可以是客户端也可以是服务器端(例如,在公司中,客户支持的电话是服务器,但你家里的电话主要是客户端)
因此,网络中的套接字是绑定到一对(ip,端口)=(地址,服务)的虚拟通信设备。
注意:
A machine, a computer, a host, a mobile, or a PC can have multiple addresses , multiple open ports, and thus multiple sockets. Like in an office you can have multiple telephones with multiple telephone numbers and multiple people to talk to. Existence of an open/active port necessitate that you must have a socket bound to it, because it is the socket that makes the port accessible. However, you may have unused ports for the time being. Also note, in a server socket you can bind it to (a port, a specific address of a machine) or to (a port, all addresses of a machine) as in the telephone you may connect many telephone lines (telephone numbers) to a telephone or one specific telephone line to a telephone and still you can reach a person through all these telephone lines or through a specific telephone line. You can not associate (bind) a socket with two ports as in the telephone usually you can not always have two people using the same telephone at the same time . Advanced: on the same machine you cannot have two sockets with same type (client, or server) and same port and ip. However, if you are a client you can open two connections, with two sockets, to a server because the local port in each of these client's sockets is different)
希望它能消除你的疑虑
其他回答
套接字是一种数据I/O机制。端口是通信协议的契约概念。套接字可以没有端口而存在。一个端口可以没有特定的套接字而存在(例如,如果同一个端口上有几个活动的套接字,这可能是某些协议允许的)。
端口用于确定接收端应该将数据包路由到哪个套接字,在许多协议中,但它并不总是必需的,接收套接字的选择可以通过其他方式完成——端口完全是网络子系统中协议处理程序使用的工具。例如,如果协议不使用端口,数据包可以到所有侦听套接字或任何套接字。
An application consists of pair of processes which communicate over the network (client-server pair). These processes send and receive messages, into and from the network through a software interface called socket. Considering the analogy presented in the book "Computer Networking: Top Down Approach". There is a house that wants to communicate with other house. Here, house is analogous to a process, and door to a socket. Sending process assumes that there is a infrastructure on the other side of the door that will transport the data to the destination. Once the message is arrived on the other side, it passes through receiver's door (socket) into the house (process). This illustration from the same book can help you: Sockets are part of transport layer, which provides logical communication to applications. This means that from application's point of view both hosts are directly connected to each other, even though there are numerous routers and/or switches between them. Thus a socket is not a connection itself, it's the end point of the connection. Transport layer protocols are implemented only on hosts, and not on intermediate routers. Ports provide means of internal addressing to a machine. The primary purpose it to allow multiple processes to send and receive data over the network without interfering with other processes (their data). All sockets are provided with a port number. When a segment arrives to a host, the transport layer examines the destination port number of the segment. It then forwards the segment to the corresponding socket. This job of delivering the data in a transport layer segment to the correct socket is called de-multiplexing. The segment's data is then forwarded to the process attached to the socket.
尽可能简单地说,套接字和端口之间没有物理区别,例如PATA和SATA之间的区别。它们只是一些读写网卡的软件。
A port is essentially a public socket, some of which are well-known/well-accepted, the usual example being 80, dedicated to HTTP. Anyone who wants to exchange traffic using a certain protocol, HTTP in this instance, canonically goes to port 80. Of course, 80 is not physically dedicated to HTTP (it's not physically anything, it's just a number, a logical value), and could be used on some particular machine for some other protocol ad libitum, as long as those attempting to connect know which protocol (which could be quite private) to use.
套接字本质上是一个私有端口,为连接方知道但其他人不一定知道的特定目的而建立。底层传输层通常是TCP或UDP,但也不一定非得如此。最基本的特征是两端都知道发生了什么,不管发生了什么。
这里的关键是,当在某个端口上接收到连接请求时,应答握手包括有关为服务特定请求者而创建的套接字的信息。后续通信通过该(私有)套接字连接进行,而不是服务继续侦听连接请求的公共端口连接。
In a broad sense, Socket - is just that, a socket, just like your electrical, cable or telephone socket. A point where "requisite stuff" (power, signal, information) can go out and come in from. It hides a lot of detailed stuff, which is not required for the use of the "requisite stuff". In software parlance, it provides a generic way of defining a mechanism of communication between two entities (those entities could be anything - two applications, two physically separate devices, User & Kernel space within an OS, etc)
端口是端点标识符。它区分一个端点和另一个端点。在网络级别,它将一个应用程序与另一个应用程序区分开来,以便网络堆栈可以将信息传递给适当的应用程序。
端口和插座可以比作银行分行。
“银行”的门牌号与IP地址类似。 银行有不同的部分,比如:
储蓄帐务部 个人贷款部 房屋贷款部 投诉部门
因此,1(储蓄账户部)、2(个人贷款部)、3(住房贷款部)和4(申诉部)是端口。
现在让我们假设你要开一个储蓄账户,你去了银行(IP地址),然后你去了“储蓄账户部门”(端口号1),然后你遇到了在“储蓄账户部门”工作的一名员工。让我们称他为SAVINGACCOUNT_EMPLOYEE1,用于开户。
SAVINGACCOUNT_EMPLOYEE1是套接字描述符,因此可能存在 SAVINGACCOUNT_EMPLOYEE1到SAVINGACCOUNT_EMPLOYEEN。这些都是套接字描述符。
同样地,其他部门将有员工在他们之下工作,他们类似于插座。
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