[SR-Users] TCP connection lifetime

[Daniel-Constantin Mierla]

Hello,

On 26.03.19 17:16, Aymeric Moizard wrote:
> Hi Again,
>
> Here is an issue with TCP connection being kept for more:
>
> Yesterday, I have discovered that a User-Agent (<Avaya IP Phone 1120E
> (SIP1120e.04.04.30.00)> tried to register a lot. It was sending
> REGISTER over new established TCP socket *every 2 seconds*.
>
> All the REGISTER was rejected with 401. (may be the device was
> misconfigured? or not receiving any of my answer? I can't tell)
>
> NOTE: You can see the expires header was very large: 86400, ie: 24
> hours...
>
> I was checking the TCP/TLS connections on my server and discovered
> more than 1000 TCP established connection to that user/ip, and thus, I
> have tried to understand what happened.
>
> Checking the logs, I received 4855 REGISTER from this device from "Mar
> 25 03:47:09" to "Mar 25 07:56:13" which is a rate of approx one new
> TCP connection every 2.5 seconds...
>
> Today, I decided to check it again around 11am.
>
> jack at sip:~$ sudo kamctl stats tcp
> {
>   "jsonrpc":  "2.0",
>   "result": [
>     "tcp:con_reset = 1857",
>     "tcp:con_timeout = 35927",
>     "tcp:connect_failed = 25",
>     "tcp:connect_success = 2",
>     "tcp:current_opened_connections = 2291",
>     "tcp:current_write_queue_size = 0",
>     "tcp:established = 80778",
>     "tcp:local_reject = 0",
>     "tcp:passive_open = 80776",
>     "tcp:send_timeout = 2",
>     "tcp:sendq_full = 0"
>   ],
>   "id": 7305
> }
>
> There was still A LOT of established connections. And the connections
> have been established more than 24 hours ago.
>
> At 11H16:
> $> lsof -n -l | grep kamailio | grep TCP | grep 41.234.242.69 | grep
> ESTA | wc -l
> 1161
> At 11H22:
> $> lsof -n -l | grep kamailio | grep TCP | grep 41.234.242.69 | grep
> ESTA | wc -l
> 1018
> At 11H35:
> $> lsof -n -l | grep kamailio | grep TCP | grep 41.234.242.69 | grep
> ESTA | wc -l
> 655
> At 13H
> $> lsof -n -l | grep kamailio | grep TCP | grep 41.234.242.69 | grep
> ESTA | wc -l
> 0
>
> So the established connections are all gone now.
>
> Between 11h16 and 11H35, I was seeing the server regularly sending
> [FIN, ACK] over each TCP established connection, with retransmissions
> for all of them. (no incoming trafic)
>
> I do not have numbers/capture/stats, but I think that kamailio was
> already closing some
> connection yesterday. I don't know when kamailio started to try
> closing those connections.
>
> I'm now back with this status:
>
> At 13pm:
> jack at sip:~$ sudo kamctl stats tcp
> {
>   "jsonrpc":  "2.0",
>   "result": [
>     "tcp:con_reset = 1896",
>     "tcp:con_timeout = 38042",
>     "tcp:connect_failed = 26",
>     "tcp:connect_success = 2",
>     "tcp:current_opened_connections = 939",
>     "tcp:current_write_queue_size = 0",
>     "tcp:established = 81950",
>     "tcp:local_reject = 0",
>     "tcp:passive_open = 81948",
>     "tcp:send_timeout = 2",
>     "tcp:sendq_full = 0"
>   ],
>   "id": 12734
> }
>
> With around 155 registration entries using TCP and TLS in my location
> database.
>
> As you can see, tcp:current_opened_connections = 939 is still pretty
> high compared to
> my currently registred users.
>
> I have "modparam("registrar", "max_expires", 86400)", because I'm
> keeping contact entries (even with TCP connection down) for push
> notifications.
>
> I have "tcp_connection_lifetime=3600" configured.
>
> Question 1
>
> With "tcp_connection_lifetime=3600", I would expect kamailio to close
> the established connection after 3600 seconds without traffic. It is
> pretty obvious that no data has been exchanged over the 4855
> established connection during a day.
>
> Despite the issue with the Avaya phones is solved automatically after
> a day, I guess similar stuff or happening, at a different rate, for
> other users as well. (because  current_opened_connections is way
> higher than registred TCP/TLS users)


Yes, tcp connections should be closed if no traffic on them for the
lifetime duration.


>
> Question 2
>
> I can list TLS connection with "kamctl rpc tls.list"
> Can I get a similar list for TCP? (lsof returns a lot of duplicates...)


Yes, see:

http://www.kamailio.org/docs/docbooks/devel/rpc_list/rpc_list.html#core.tcp_list

Maybe you can compare what is listed by the rpc command to see what
kamailio actually sees as active connections.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla -- www.asipto.com
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio World Conference - May 6-8, 2019 -- www.kamailioworld.com

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