tcp和udp协议学习

tcp关键报文：

tcp三次握手建立连接，三次或四次分手断开连接

 tcp wireshark抓包;

udp wireshark 抓包：

 tcp端口扫描器

from  scapy.all import *
ifcace="VMware Virtual Ethernet Adapter for VMnet8"
dip='192.168.85.130'
sp=random.randint(40000,60000)
dp=[80,8080,1433,3306]
for dprt in dp:
    tcp_p=IP(dst=dip)/TCP(dport=dprt,sport=sp)
    ans,unans=sr(tcp_p,verbose=0,timeout=2,iface=ifcace)
    for req,rep in ans:
        if rep[TCP].flags=='SA':
            print(rep.sprintf("%IP.src%的%TCP.sport%是开放的"))
        else:
            print(rep.sprintf("%IP.src%的%TCP.sport%是没有开放的"))
    for req in unans:
        print(req.sprintf("%IP.src%的%TCP.sport%是没有开放的"))

实现效果

 udp端口扫描器，udp端口不开放会icmp的端口不可达，也就是type=3

from  scapy.all import *
ifcace="VMware Virtual Ethernet Adapter for VMnet8"
dip='192.168.85.130'
sp=random.randint(40000,60000)
dp=[137,500,138,100]
for dprt in dp:
    udp_p=IP(dst=dip)/UDP(sport=sp,dport=dprt)
    ans,unans=sr(udp_p,iface=ifcace,timeout=2,verbose=0)
    for req,rep in ans:
        if rep[ICMP].type==3:
            print("{}的udp{}端口没有开放".format(dip,dprt))
        else:
            print("{}的udp{}端口开放".format(dip,dprt))
    for req in unans:
        print("{}的udp{}端口开放".format(dip,dprt))

实现效果：