func handlePacket(handle *pcap.Handle, packet gopacket.Packet) {
ethLayer := packet.LinkLayer()
if ethLayer == nil {
return
}
eth, ok := ethLayer.(*layers.Ethernet)
if !ok {
return
}
ipLayer := packet.NetworkLayer()
if ipLayer == nil {
return
}
ip, ok := ipLayer.(*layers.IPv4)
if !ok {
return
}
tcpLayer := packet.Layer(layers.LayerTypeTCP)
if tcpLayer == nil {
return
}
tcp, ok := tcpLayer.(*layers.TCP)
if !ok {
return
}
// 服务器回应 SYN 请求
if tcp.SYN == true && tcp.ACK == true {
ttl := uint8(0)
switch {
case ip.TTL > 128:
//Solaris/AIX
ttl = 254 - ip.TTL
case ip.TTL > 64:
// windows
ttl = 128 - ip.TTL
default:
// linux
ttl = 64 - ip.TTL
}
switch {
case ttl > 10:
ttl -= 4
case ttl > 5:
ttl -= 2
case ttl > 2:
ttl -= 1
default:
return
}
ack := tcp.Seq + uint32(len(tcp.Payload)) + 1
data := []byte{1, 2, 3, 4, 5, 6, 7, 8, 9}
seq := tcp.Ack
sendPacket(handle, eth.DstMAC, eth.SrcMAC, ip.DstIP, ip.SrcIP, tcp.DstPort, tcp.SrcPort, ip.Id+123, ttl, seq, ack, 258, data)
seq += 2048
sendPacket(handle, eth.DstMAC, eth.SrcMAC, ip.DstIP, ip.SrcIP, tcp.DstPort, tcp.SrcPort, ip.Id+123, ttl, seq, ack, 258, nil)
//go fmt.Printf("伪重置 %v:%v 的 tcp 连接。\r\n", ip.SrcIP, tcp.SrcPort)
}
}