In the same local area network (LAN) :

1. The Macbook
IP: 192.168.100.29
The HTTP Proxy: 192.168.100.39:8080

2. The web server
IP: 192.168.100.44

HTTP proxy server
3.IP: 192.168.100.39
Port: 8080

Requirements:
Three hosts on the same network segment, the Macbook HTTP proxy configuration for 192.168.100.39:8080, expect the Macbook when accessing a web server sends a request to the proxy server first by the proxy server to a web server to forward the request, main is to want to intercept the Macbook request modifications in the proxy server,
Question:
Above process is no problem in the beginning, but the Macbook after using several times to access the web server doesn't walk, the agent directly to the web server sends the request, LAN segments will modify can use again, after a period of time there will be the problem,
Thought it was learned a routing table, but empty routing table has not solved,