Limiting open port RST response when using UrBackup

[revengineer]

FreeNAS 11.3U4.1 reports the following error when using UrBackup:

Code:

Aug  7 18:41:57 max kernel: Limiting open port RST response from 372 to 200 packets/sec
Aug  7 18:41:57 max kernel: Limiting open port RST response from 372 to 200 packets/sec
Aug  7 18:49:19 max kernel: Limiting open port RST response from 235 to 200 packets/sec
Aug  7 18:49:19 max kernel: Limiting open port RST response from 235 to 200 packets/sec
...

The server is behind a firewall so this is all friendly local traffic. Can I change the allowed limit from 200 to 300 packets? If so, how do I do that?

 

[Samuel Tai]

The server is behind a firewall so this is all friendly local traffic.

Are you sure about that? If you've created a port forward for 55413 and/or 55414 on your router, you may be seeing hack attempts coming from the Internet.

 

[revengineer]

Yes, very certain. Firewall is pfSense running on separate hardware. There is a single open port forwarded to an OpenVPN server and no UPnP. I had more messages like the one above today, and again it was correlated with traffic from a UrBackup client. So is there a way to increase the limit?

 

[Samuel Tai]

No, this is unfortunately hard-coded in the kernel. What you can do to silence these notices per the blackhole(4) man page is to set some sysctl tunables:

Code:

     sysctl net.inet.tcp.blackhole=2
     sysctl net.inet.udp.blackhole=1

This appears unfortunately due to UrBackup not correctly using TCP.

 

[revengineer]

Thank you @Samuel Tai. That would explain why my searches came up empty, although I did not find the hardcoding explicitly stated. I have seen the tunables but they seem to only hide the problem. I am not bothered by the messages, so I will leave as is. I will take this to the UrBAckup forum and ask whether this is a known issue.

 

[revengineer]

Code:

     sysctl net.inet.tcp.blackhole=2
     sysctl net.inet.udp.blackhole=1

I set the sysctl tunables above through the web interface under system -> tunables and rebooted the FreeNAS server. I am still getting these messages though. Does anyone know why FreeNAS might be ignoring the tunables?