TP-LINK freeze connection to self
|Reported by:||checho||Owned by:|
Tested on multiple routers of TP-LINK TL-WR740N v2/3, TL-WR741ND v2, TL-WR841Nv7, confirmed frequent freezes of connection to the router itself.
Let's say we do a ssh connection to a device, user comes through WAN port. Console freezes as we are typing commands in the shell. As it is frozen we continue typing no matter that nothing is shown. This is exactly as if the physical connection to the router is lost.
For added weirdness if we open another console and try to open another ssh connection on another socket, it will work. We will be able to open another ssh session while the first one is still frozen. We type commands that we see executed promptly without any problem.
No matter if we open a second console (i.e. another socket) on the router to self, the frozen connection will unfreeze in some 30-60 seconds or so. We see everything that was sent to the shell during the period when connection was frozen.
This behavior is only seen when connection is established to the router self (INPUT). Also I don't think it is a firewall issue because if it was it would drop the connections closing the sockets but not freezing them for a while instead.
For added weirdness the same problem appears when connecting to the router on port 80 (that is, browsing the admin pages). We click on a link and suddenly the router stops responding. If we open another browser pointing to the router administration it will work. Exactly the same.
FORWARD-ed connections to world from clients behind the router have no problem being processed even during the time the connection to the router was frozen.
Affected builds are all official from 15778 to 18024. I have not made tests with the latest one running the new kernel, I will try to test it in a matter of days.