SYN flooding on RT-AC68U & dual WAN problem with DHCP

[timosu]

hi mates

as first thank you for the very good fw from merlin for my asus rt ac68u... on dual wan i got some problems... is it possible to change the dhcp release time? i see that there is only a option for agressive mode and normal mode... after 1h i got disconnects on my WAN1 connetion.

2nd question.... i got a log entry as follows:

Sep 30 02:53:46 kernel: TCP: Possible SYN flooding on port 1723. Sending cookies.

on this time there was no client active behind the router. all devices was power down... only modem and router was power up... what is it? ddos?

thank you

best regards

timo

 

[RMerlin]

2nd question.... i got a log entry as follows:

Sep 30 02:53:46 kernel: TCP: Possible SYN flooding on port 1723. Sending cookies.

on this time there was no client active behind the router. all devices was power down... only modem and router was power up... what is it? ddos?

Port 1723 is used by the PPTP. This is something hitting your router on the WAN side while you have the PPTP server enabled, and has nothing to do with the LAN clients.

 

[timosu]

thank you for the fast answer.... did now shut down the pptp... did you have a solution for my dhcp problem?
i use a cisco cable modem on WAN1 and the dhcp release time is 1h... i dont know why. every 1h i get a short cut off because ip is expired and renewing

 

[RMerlin]

thank you for the fast answer.... did now shut down the pptp... did you have a solution for my dhcp problem?
i use a cisco cable modem on WAN1 and the dhcp release time is 1h... i dont know why. every 1h i get a short cut off because ip is expired and renewing

No idea, I don't deal with the Dual Wan code, sorry.

 

[Shonk]

I have been getting this for the last hour

i presume its someone trying to brute force the pptp server?

Jan 23 16:22:13 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:23:18 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:24:18 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:25:19 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:26:19 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:27:20 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:28:22 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:29:23 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:30:27 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:31:27 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:32:28 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:33:31 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:34:31 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:35:32 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:36:33 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:37:33 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:38:33 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:39:34 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:40:34 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:41:35 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:42:35 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:43:36 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:44:38 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:45:43 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:46:46 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:47:47 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:48:49 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:49:55 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:50:56 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:51:57 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:52:57 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:53:59 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:55:03 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:56:05 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:57:13 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:58:13 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 16:59:16 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:00:18 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:01:20 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:02:22 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:03:24 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:04:28 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:05:28 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:06:29 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:07:31 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:08:34 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:09:40 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:10:40 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:11:40 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:12:41 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:13:41 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:14:42 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:15:43 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:16:45 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:17:46 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:18:47 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:19:48 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:20:48 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:21:50 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:22:50 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:23:52 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:24:52 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:25:55 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:26:55 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:27:57 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:29:01 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:30:03 kernel: possible SYN flooding on port 1723. Sending cookies.
Jan 23 17:33:04 kernel: possible SYN flooding on port 1723. Sending cookies.