3.6.15 TCP/IP Tuning - tcp_tcpsecure

Information

The tcp_tcpsecure parameter value determines if the system is protected from three specific vulnerabilities-
o Fake SYN - This is used to terminate an established connection. A tcp_tcpsecure value of 1 protects the system from this vulnerability.
o Fake RST - As above, this is used to terminate an established connection. A tcp_tcpsecure value of 2 protects the system from this vulnerability.
o Fake data - A hacker may inject fake data into an established connection. A tcp_tcpsecure value of 4 protects the system from this vulnerability.

The tcp_tcpsecure parameterwill be set to 7. This means that the system will be protected from any connection reset and data integrity attacks.

Solution

In /etc/tunables/nextboot, add the tcp_tcpsecure entry-

no -p -o tcp_tcpsecure=7

This makes the change permanent by adding the entry into /etc/tunables/nextboot.

See Also

https://workbench.cisecurity.org/files/528