英文:
Client sends [RST] after receive [SYN, ACK]
问题
我正在尝试与从互联网下载的服务器进行握手。但是当客户端接收到[SYN，ACK]时，它会发送[RST]。不知道发生了什么。已经检查了确认和序列号，但一切似乎都正常。
在Wireshark中，我得到了这个：
![客户端在接收到 [SYN, ACK] 后发送 [RST]。](https://i.stack.imgur.com/50pig.png)
这是客户端握手源代码：
from scapy.all import *
src_ip = "192.168.43.34"
dst_ip = "192.168.43.115"
src_port = random.randint(1024, 65535)
dst_port = 502
seq_nr = random.randint(444, 8765432)
ack_nr = 0
# 创建SYN数据包
ip = IP (src = src_ip, dst = dst_ip)
syn = TCP(sport = src_port, dport = dst_port, flags='S', seq = seq_nr, ack = ack_nr)
pkt_syn = ip / syn
pkt_syn.show()
# 发送SYN数据包并接收SYN/ACK数据包
print('发送SYN')
pkt_syn_ack = sr1(pkt_syn)
print('接收到ACK')
pkt_syn_ack.show()
# 创建ACK数据包
ack_nr = pkt_syn_ack.seq + 1
seq_nr = seq_nr + 1
ack = TCP(sport = src_port, dport = dst_port, flags = 'A', seq = seq_nr, ack = ack_nr)
send(ip / ack)
...
如您所要求，这是源代码的翻译部分，不包含其他内容。
英文:
I am trying to do a handshake with a server I downloaded from the internet. But when the client receives [SYN, ACK] it sends back a [RST]. Have no idea what is happening. Already checked the acknowledge and sequence number but everything seems ok.
In wireshark I got this:
Here is the handshake client source code:
from scapy.all import *
src_ip = "192.168.43.34"
dst_ip = "192.168.43.115"
src_port = random.randint(1024, 65535)
dst_port = 502
seq_nr = random.randint(444, 8765432)
ack_nr = 0
# Create SYN packet
ip = IP (src = src_ip, dst = dst_ip)
syn = TCP(sport = src_port, dport = dst_port, flags='S', seq = seq_nr, ack = ack_nr)
pkt_syn = ip / syn
pkt_syn.show()
# send SYN packet and receive SYN/ACK packet
print('Sending SYN')
pkt_syn_ack = sr1(pkt_syn)
print('ACK received')
pkt_syn_ack.show()
# Create the ACK packet
ack_nr = pkt_syn_ack.seq + 1
seq_nr = seq_nr + 1
ack = TCP(sport = src_port, dport = dst_port, flags = 'A', seq = seq_nr, ack = ack_nr)
send(ip / ack)
...
答案1
得分: 3
问题在于您的操作系统接收到了SYN-ACK数据包，但不知道为什么发送该数据包（因为操作系统本身没有启动握手），所以重置了连接。
您可以在这里找到一些解决方案（适用于Linux）-
https://stackoverflow.com/questions/9058052/unwanted-rst-tcp-packet-with-scapy
另一个选择是使用与操作系统不同的IP地址，或者在Windows中关闭所使用接口的IP协议栈（仅当该接口仅用于此用途时）。
英文:
The problem is that your OS is receiving the SYN-ACK packet, has no idea why it was sent (as the OS itself didn't start a handshake) and reset the connection.
You can find some solutions here (for Linux)-
https://stackoverflow.com/questions/9058052/unwanted-rst-tcp-packet-with-scapy
Another option is to use a different IP than the OS's, or in Windows turn off the IP stack of the used interface (only if this is the only thing that you use this interface for!)
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