SYN-FLOOD to LDAPS port from clients

[Pete Nesbitt]

On May 24, 2004 07:09 pm, Ryan Golhar wrote:
> I'm running an LDAP server to authenticate users using secure ldap on
> port 636 -- standard port.  The client access the server and I get the
> following messages on server from the firewall:
>
> May 23 04:02:10 myserver kernel: SYN-FLOOD: IN=eth0 OUT=
> MAC=00:07:e9:ac:2a:22:00:04:c1:55:a7:c2:08:00 SRC=192.168.10.122
> DST=192.168.10.2 LEN=60 TOS=0x00 PREC=0x00 TTL=59 ID=31600 DF PROTO=TCP
> SPT=36082 DPT=636 WINDOW=5840 RES=0x00 SYN URGP=0
>
> I get these quite frequently from each client.  My iptables firewall
> rule is as follows:
>
> On the input chain:
> -A LINWIZ-INPUT -p tcp -m tcp --syn -j SYN-FLOOD
>
> On the SYN-FLOOD chain:
> -A SYN-FLOOD -m limit --limit 1/s --limit-burst 4 -j RETURN
> -A SYN-FLOOD -j LOG --log-prefix "SYN-FLOOD: "
> -A SYN-FLOOD -j DROP
>
> Are my rules incorrect, or is it truly ldap clients flooding the server?
>
> -----
> Ryan Golhar
> Computational Biologist
> The Informatics Institute at
> The University of Medicine & Dentistry of NJ
>
> Phone: 973-972-5034
> Fax: 973-972-7412
> Email: golharam at umdnj.edu


Hi Ryan,
What other rules are in place? 
Can you either post your iptables script or else the output of "iptables -L"?

Are the clients successfulling connecting/authenticating?
-- 
Pete Nesbitt, rhce