Contents
1. IV SHARED IPS COLLECTION
B. Cloud Servers
- Linode opens port 25 for outbound communication
C. Proxy Services
TABLE V. OVERVIEW OF OPEN PROXY USABILIT
after conducting dedicated experiments, we identified a total of 1,552 HTTP proxies, 1,513 HTTP transparent proxies, 1,307 HTTP tunnels, 360 SOCKS4 proxies, and 127 SOCKS5 proxies that successfully connected to port 80 on our server. This indicates that these proxy servers are indeed providing proxy services and can be used freely without authentication.
As mentioned earlier, proxy servers may impose restric- tions on target ports. Thus, we also tested the connectivity to port 25, revealing that 1,035 HTTP proxies, 1,136 HTTP transparent proxies, 832 HTTP tunnels, 243 SOCKS4 proxies, and 60 SOCKS5 proxies successfully connected to port 25 on our server via HTTP protocol.
It is evident that the number of proxy servers allowing con- nections to port 25 is significantly lower than those allowing connections to port 80.
This is because port 25 is the default port for SMTP services, so many proxy servers restrict access to prevent abuse, but there still is a considerable number of open proxies still allow connections to port 25.
D. Serverless Functions