gburlingame
Occasional Visitor
Hello,
I noticed my system log was filled with error messages of the form:
net_ratelimit: n callbacks suppressed
Where n is a small number, typically less than 15.
After doing some of my own research, I tracked it down to three WeMo Mini smart plugs that I purchased from Amazon for the holidays. I used them with Apple HomeKit to control 3 different illuminated Christmas decorations. WeMo is a brand name for Belkin.
When I log into the router and type the command dmesg, I see a flood of messages like this:
TCP: Possible SYN flooding on port 58863. Dropping request.
The port number remains constant until I reboot the router, and then in becomes a different port number.
I then found this handy command netstat -nta | egrep "State|58863" which creates a long list of many open connections in the TIME_WAIT state. (Note: I didn't know what any of this meant until I did some research.)
tcp 0 0 192.168.0.1:58863 192.168.0.58:47275 TIME_WAIT
I experimented a bit, and if I only have 1 switch plugged in my system log remains empty. If I add a second switch, it remains empty. After adding the 3rd switch, I start to get the net_ratelimit messages.
I think perhaps the WeMo Mini's aren't quite doing something properly and theyare triggering a mechanism in the RT-AC88U intended to prevent SYN flooding? It doesn't seem to be causing any problems, at least none that I am aware of.
I wanted to share this with the community. Thank you for sharing any thoughts or ideas.
Thank you for reading.
Best regards,
Greg
I noticed my system log was filled with error messages of the form:
net_ratelimit: n callbacks suppressed
Where n is a small number, typically less than 15.
After doing some of my own research, I tracked it down to three WeMo Mini smart plugs that I purchased from Amazon for the holidays. I used them with Apple HomeKit to control 3 different illuminated Christmas decorations. WeMo is a brand name for Belkin.
When I log into the router and type the command dmesg, I see a flood of messages like this:
TCP: Possible SYN flooding on port 58863. Dropping request.
The port number remains constant until I reboot the router, and then in becomes a different port number.
I then found this handy command netstat -nta | egrep "State|58863" which creates a long list of many open connections in the TIME_WAIT state. (Note: I didn't know what any of this meant until I did some research.)
tcp 0 0 192.168.0.1:58863 192.168.0.58:47275 TIME_WAIT
I experimented a bit, and if I only have 1 switch plugged in my system log remains empty. If I add a second switch, it remains empty. After adding the 3rd switch, I start to get the net_ratelimit messages.
I think perhaps the WeMo Mini's aren't quite doing something properly and theyare triggering a mechanism in the RT-AC88U intended to prevent SYN flooding? It doesn't seem to be causing any problems, at least none that I am aware of.
I wanted to share this with the community. Thank you for sharing any thoughts or ideas.
Thank you for reading.
Best regards,
Greg