If you are using ZyXEL Prestige 650 Series, e.g. Prestige 650-R, like me, you must be aware of its limitation. According to its support note, this router does not limit the number of the users but the number of the sessions. In particular, the Prestige 650 supports concurrent 1024 sessions. A session is an end-to-end pair of two IP addresses. For example, whenever you view a web page, you are probably establishing 1 to 10 sessions depending on browser settings, internal frames, and images in that page. Instant messengers hold at least one connection. Assuming that a machine will always establish at least 10 connections, as a result, there are approximately 500 sessions for 50 machines. For more precisely, you can view the active sessions using telnet interface. Just follow below procedure.

1. Telnet to the router and enter the password
2. Type 24 and press enter to go to System Maintenance menu
3. Type 8 and press enter to go to Command Interpreter Mode menu
4. At the prompt, type ip nat iface wanif0 st command and press enter

Technorati Tags: English, IT, Security, Review, Tips and Tricks, ADSL, Router, ZyXEL, Prestige, NAT