[syslog-ng]Problem with TCP connection not timing out

[ARGEXT-HIDALGO, FRANCISCO]

I'm really not sure what the problem is, I'm logging with a server in =
different countries and they send through TCP the logs to a central =
server. The problem I'm having is that the central server is not =
dropping TCP connections that no longer exist.
As an example:

CENTRAL SERVER:
TCP
   Local Address        Remote Address    Swind Send-Q Rwind Recv-Q  =
State
-------------------- -------------------- ----- ------ ----- ------ =
-------
CENTRAL.shell           syslogA.33969   5840      0 10136      0 =
ESTABLISHED
CENTRAL.shell           syslogB.4930     5840      0 10136      0 =
ESTABLISHED
CENTRAL.shell           syslogC.33924 24820      0  8760      0 =
ESTABLISHED
CENTRAL.shell           syslogC.33925 24820      0  8760      0 =
ESTABLISHED
CENTRAL.shell           syslogD.44925  5840      0 10136      0 =
ESTABLISHED
CENTRAL.shell           syslogE.32783 24820      0  8760      0 =
ESTABLISHED
CENTRAL.shell           syslogC.33926 24820      0  8760      0 =
ESTABLISHED
CENTRAL.22              host.1624 51968      0 10136      0 ESTABLISHED
CENTRAL.shell           syslogD.44934  5840      0 10136      0 =
ESTABLISHED

SYSLOGC:
TCP: IPv4
   Local Address        Remote Address    Swind Send-Q Rwind Recv-Q  =
State
-------------------- -------------------- ----- ------ ----- ------ =
-------
syslogC.33926         CENTRAL.shell  8760      0 24820      0 =
ESTABLISHED
SyslogC.22            host.4663            57920      0 24616      0 =
ESTABLISHED


Notice that the active conection is the one from SyslogC port 33926, but =
CentralSyslog has 3 established connections (33924, 33925 and 33926), =
33924 is active since some days ago, but doesn't exist in the original =
server. The problem is that my total connections allowed start to fill =
up and then I can no longer connect.
Any ideas on what could this be?
Thank you.