• If you want to limit the simultaneous sessions a user can have this this page is for you.

• If you are driven by sales of vouchers, limiting the amount of people who can use the voucher at one time can result in more sales.
• If you are very strict on limiting the amount of date a user can use, it is wise to restrict the sessions even to only one in order to ensure accurate data cap calculations.

• You might get more support calls since it may just happen that a person was connected through the captive portal and got disconnected.
• The back-end still thinks he is connected.
• If the person then tries to connect again and there is a limit on the sessions to e.g. 1, he will not be able to connect again.
• Usually there is a reply attribute called Idle-Timeout which you can set to a low value to auto-disconnect the user from the Captive Portal's side.
• Another option is to let the Back-end auto close stale sessions by editing the Dynamic Client under RADIUS menu and go to Dynamic Client → Enhancements and select Auto Close Stale Sessions with a time.
• These items are just a heads-up before you implement this limit.

• Check if it is enabled in FreeRADIUS

vi /etc/freeradius/mods-config/sql/main/mysql/queries.conf

• The following section needs to be active

#
#  Uncomment simul_count_query to enable simultaneous use checking
#
simul_count_query = "\
        SELECT COUNT(*) \
        FROM ${acct_table1} \
        WHERE username = '%{SQL-User-Name}' \
        AND acctstoptime IS NULL"
 
simul_verify_query = "\
        SELECT \
                radacctid, acctsessionid, username, nasipaddress, nasportid, framedipaddress, \
                callingstationid, framedprotocol \
        FROM ${acct_table1} \
        WHERE username = '%{SQL-User-Name}' \
        AND acctstoptime IS NULL"

• Restart if you made changes

#14.04
service freeradius stop
service freeradius start
#16.04
sudo systemctl restart freeradius.service

• Consider the following screenshot

• Here it is preventing a second connection