CoA server conception

[Yuriy Ivkin]

Greetings!

After few hours of googling I think I understood. The only not clear 
thing: how freeradius deside to send a CoA message or not ?

Comments from sites-available/originate-coa:

#  CoA packets can be originated when a normal Access-Request or
#  Accounting-Request packet is received.  Simply update the
#  "coa" list:
#
#       update coa {
#              &User-Name = "%{User-Name}"
#              &Acct-Session-Id = "%{Acct-Session-Id}"
#              &NAS-IP-Address = "%{NAS-IP-Address}"
#       }
#
#  And the CoA packet will be sent.  You can also send Disconnect
#  packets by using "update disconnect { ...".
#

What is the "Simply update the  "coa" list" means ? Changing of a site 
configuration in accounting section like this

update coa {
                User-Name = "%{User-Name}"
                Acct-Session-Id = "%{Acct-Session-Id}"
                NAS-IP-Address = "%{NAS-IP-Address}"
}

and restart service ?

Will the CoA message be generated in response for every acct request of 
active sessions ? That has no sense...

03.03.2023 11:33, Yuriy Ivkin пишет:
> Greetings!
>
>  I am trying to understand the conception of coa server. What 
> functionality does it brings ? Is it a some kind of proxy ?
>
> For example, I have a NAS server with configured coa port. I can send 
> a disconnect request directly into it. If I configure a coa server on 
> a freeradius server, will I be able to send a disconnect request to 
> the freeradius instead and that is all?
>
> Thanks in advance for your answers!
>
-- 
Best regards,
Yuriy Ivkin