Networks
Four Layers of TCP/IP model.
{:.warning}
TCP/IP
Model
TCP&UDP
Tips: HOST means Domain or IP address.
TCP(20bits) and UDP(8bits) could use a same port in a host without conflict.、
FTP
FTP is often secured with SSL/TLS(FTPS) or SFTP.
FTP通信中使用两条TCP连接:
- 控制
- 数据传输
FTP uses multiple TCP connections:
- control channel(port 21)
- data channel(port 20)
HTTP
Request and Response
Request:
GET /hello.txt HTTP/1.1
Host: www.mysite.com
Accept-Language: en
Response:
TCP socket
Note that if the client is the type of str
, the encode()
it:
message = "Current time is " + str(dt)
conn.send(message.encode())