[syslog-ng] allowed concurrent connections - bug?

Evan Rempel erempel at uvic.ca
Thu Feb 17 18:01:18 UTC 2022

I am having an issue that is a little difficult to reproduce so I wanted 
some input from others.

I have a syslog-ng 3.35.1 that has a TLS source defined with 

After some time the server starts logging a lot of messages

syslog-ng[12802]: Number of allowed concurrent connections reached, 
rejecting connection; client='AF_INET(XXXX:61062)', 
local='AF_INET(YYYY:6514)', group_name='client_network_tcp', 
location='/etc/syslog-ng/syslog-ng.server.conf:61:9', max='10000'

To the best of my ability I can only find about 2500 actual connections.

Both lsof and netstat report around the 2500 connections.

I had to restart syslog-ng to stop this situation.

Has anyone seen this behavior before?

I get a lot of TLS connections without a certificate.

Error reading RFC6587 style framed data

Pperhaps the counters are not decremented for those timed out connections?

Evan Rempel

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