Hardering the TCP/IP to SYN attacks

[chrismfz]

Hello. Trying to enable this on my vps
As in http://www.securityfocus.com/infocus/1729 says,
...
Operating system: Linux RedHat

RedHat, like other Linux operating systems, has implemented a SYN cookies mechanism which can be enabled in the following way:

# echo 1 > /proc/sys/net/ipv4/tcp_syncookies
.....
then just for trying it

[root@sky root]# id
uid=0(root) gid=0(root) ...

[root@sky root]# cat /proc/sys/net/ipv4/tcp_syncookies
0

[root@sky root]# echo 1 > /proc/sys/net/ipv4/tcp_syncookies
-bash: /proc/sys/net/ipv4/tcp_syncookies: Operation not permitted

Why ? Strict permissions on vps accounts or because the nature of a vps system ?

Regards,
Chris

[Gwaihir]

On dione, the shared server I am on, this is enabled.

Have you checked the permissions on that file (ls -al)? If you really can't touch it, it is probably something support has to enable node wide (if they think it's a good idea).