The Photon operating system must use Transmission Control Protocol (TCP) syncookies.

A TCP SYN flood attack can cause a denial of service by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected and enables the system to continue servicing valid connection requests.

Satisfies: SRG-OS-000142-GPOS-00071, SRG-OS-000420-GPOS-00186

At the command line, run the following command:

# /sbin/sysctl -a --pattern tcp_syncookies

Expected result:

net.ipv4.tcp_syncookies = 1

If the output does not match the expected result, this is a finding.

At the command line, run the following commands:

# sed -i -e "/^net.ipv4.tcp_syncookies/d" /etc/sysctl.conf
# echo net.ipv4.tcp_syncookies=1>>/etc/sysctl.conf
# /sbin/sysctl --load