The Photon operating system must not forward IPv4 or IPv6 source-routed packets.

Source routing is an Internet Protocol mechanism that allows an IP packet to carry information, a list of addresses, that tells a router the path the packet must take. There is also an option to record the hops as the route is traversed.

The list of hops taken, the "route record", provides the destination with a return path to the source. This allows the source (the sending host) to specify the route, loosely or strictly, ignoring the routing tables of some or all of the routers. It can allow a user to redirect network traffic for malicious purposes and should therefore be disabled.

At the command line, run the following command:

# /sbin/sysctl -a --pattern "net.ipv[4|6].conf.(all|default|eth.*).accept_source_route"

Expected result:

net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.default.accept_source_route = 0 net.ipv4.conf.eth0.accept_source_route = 0 net.ipv6.conf.all.accept_source_route = 0 net.ipv6.conf.default.accept_source_route = 0 net.ipv6.conf.eth0.accept_source_route = 0

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

Note: The number of "ethx" lines returned is dependent on the number of interfaces. Every "ethx" entry must be set to "0".

At the command line, run the following command:

# for SETTING in $(/sbin/sysctl -aN --pattern "net.ipv[4|6].conf.(all|default|eth.*).accept_source_route"); do sed -i -e "/^${SETTING}/d" /etc/sysctl.conf;echo $SETTING=0>>/etc/sysctl.conf; done
# /sbin/sysctl --load