TCP⼀IP连接中服务器发送[RST,ACK],客户端应该如何回应?
推荐回答(4个)
TCP/IP详解--接收RST回应的几种情况:
1、端口未打开
服务器程序端口未打开而客户端来连接。这种情况是最为常见和好理解的一种了。去telnet一个未打开的TCP的端口可能会出现这种错误。这个和操作系统的实现有关。在某些情况下,操作系统也会完全不理会这些发到未打开端口请求。
2、请求超时
曾经遇到过这样一个情况:一个客户端连接服务器,connect返回-1并且error=EINPROGRESS。 直接telnet发现网络连接没有问题。ping没有出现丢包。用抓包工具查看,客户端是在收到服务器发出的SYN之后就莫名其妙的发送了RST。
3、提前关闭
关于TCP,我想我们在教科书里都读到过一句话,'TCP是一种可靠的连接'。 而这可靠有这样一种含义,那就是操作系统接收到的来自TCP连接中的每一个字节,我都会让应用程序接收到。
![](/picurl?url=https%3A%2F%2Fiknow-pic.cdn.bcebos.com%2F4ec2d5628535e5dd479948a366c6a7efce1b6211%3Fx-bce-process%3Dimage%252Fresize%252Cm_lfit%252Cw_600%252Ch_800%252Climit_1%252Fquality%252Cq_85%252Fformat%252Cf_auto)
扩展资料
TCP/IP连接三次握手
在TCP/IP协议中,TCP协议提供可靠的连接服务,采用三次握手建立一个连接。
第一次握手:建立连接时,客户端发送syn包(syn=j)到服务器,并进入SYN_SEND状态,等待服务器确认; SYN:同步序列编号(Synchronize Sequence Numbers)
第二次握手:服务器收到syn包,必须确认客户的SYN(ack=j+1),同时自己也发送一个SYN包(syn=k),即SYN+ACK包,此时服务器进入SYN_RECV状态;
第三次握手:客户端收到服务器的SYN+ACK包,向服务器发送确认包ACK(ack=k+1),此包发送完毕,客户端和服务器进入ESTABLISHED状态,完成三次握手。
完成三次握手,客户端与服务器开始传送数据。
1、首先,创建tcp服务器,创建的方式如下面图中所示,先创建一个net服务,然后监听connect和data事件,并对收到的数据进行确认,监听端口8431。
![](/picurl?url=https%3A%2F%2Fiknow-pic.cdn.bcebos.com%2F0b55b319ebc4b74556835a6adffc1e178a8215b2%3Fx-bce-process%3Dimage%252Fresize%252Cm_lfit%252Cw_600%252Ch_800%252Climit_1%252Fquality%252Cq_85%252Fformat%252Cf_auto)
2、创建tcp客户端,连接上面建立的tcp服务器,并发送 你好,并接收来自服务器的确认信息。
![](/picurl?url=https%3A%2F%2Fiknow-pic.cdn.bcebos.com%2F64380cd7912397dd226e75784982b2b7d0a287b3%3Fx-bce-process%3Dimage%252Fresize%252Cm_lfit%252Cw_600%252Ch_800%252Climit_1%252Fquality%252Cq_85%252Fformat%252Cf_auto)
3、下面显示的是服务器接收到的数据,并显示出来,然后向客户端发送数据确认。
![](/picurl?url=https%3A%2F%2Fiknow-pic.cdn.bcebos.com%2Fb2de9c82d158ccbfadab584609d8bc3eb13541b3%3Fx-bce-process%3Dimage%252Fresize%252Cm_lfit%252Cw_600%252Ch_800%252Climit_1%252Fquality%252Cq_85%252Fformat%252Cf_auto)
4、显示来自服务器的确认数据,这样一个tcp服务器和客户端就建立起来了。
![](/picurl?url=https%3A%2F%2Fiknow-pic.cdn.bcebos.com%2F9e3df8dcd100baa1113baac75710b912c8fc2eb3%3Fx-bce-process%3Dimage%252Fresize%252Cm_lfit%252Cw_600%252Ch_800%252Climit_1%252Fquality%252Cq_85%252Fformat%252Cf_auto)
仅从抓包信息看是服务器的一个流量控制机制启动了。服务器发回rst位,同时win置为0,是告诉客户端不要发包。按tcp流控机制来说,此时客户端应该停止发包,直至服务器发送信息告诉客户端可以继续发送。
为什么你这个syn,直接恢复rst,ack,你这个rst中seq为什么是1
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