I want to block the users of sub network to have not access to the server Radius ? I tried one like this but it doesn't work.

  • Doesn't work is not specific enough. What doesn't work, and how did you determine it doesn't work?
    – Ron Maupin
    Jul 4, 2016 at 20:32
  • Are you sure you're specifying the correct port? Some Radius servers use 1812. Try removing the port number and see if Radius is blocked. If so, you're using the wrong port.
    – Ron Trunk
    Jul 4, 2016 at 20:40
  • Users can connect to to router Home via the radius server. On the command prompt of user's coùputer i just type ssh -l admin Below the screen
    – google
    Jul 4, 2016 at 20:45
  • According to Microsoft: "UDP port 1812 is used for RADIUS authentication messages and UDP port 1813 is used for RADIUS accounting messages. Some network access servers might use UDP port 1645 for RADIUS authentication messages and UDP port 1646 for RADIUS accounting messages. By default, IAS supports receiving RADIUS messages destined to both sets of UDP ports." You may need to block more ports in your ACL.
    – Ron Maupin
    Jul 4, 2016 at 20:55

1 Answer 1


You are misunderstanding how RADIUS operates. When clients connect to the HOME router, the router connects to the RADIUS server to authenticate them. The clients never connect to the RADIUS server directly.

As @Ronmaupin suggests, you can block users on that subnet from accessing the router by applying an ACL to the VTY lines:

access-list 10 deny
access-list 10 permit any

line vty 0 4
access-class 10 in
  • It sounds like an ACL for the VTY lines is in order.
    – Ron Maupin
    Jul 4, 2016 at 21:24
  • Thank you it works. Before this i didn't know that ACL could be applied to a line VTY.
    – google
    Jul 4, 2016 at 22:45

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