Can I change the default ephemeral ports that the F5 uses for health monitoring?

I ran that command on each F5 but am still seeing it try to communicate on 43900 and lower. Do I need to perform a system reboot for the changes to take effect, or something of that nature?

That will apply after a reboot. Try, sysctl -w net.ipv4.ip_local_port_range = 49152 65535

Received this error: error: "net.ipv4.ip_local_port_range" must be of the form name=value error: Malformed setting "=" error: "49152" must be of the form name=value error: "65535" must be of the form name=value

Sorry, been awhile... sysctl -w net.ipv4.ip_local_port_range="49152 65535"

That command took. And this will ensure that the F5 will start using only these ephemeral ports without the need of a reboot, correct?

It should. And since you did the echo above, anytime it does reboot it will come back with the ephermeral range configured.

Hm, so I have found that after a reboot the port range went back to using 32768 - 61000. Furthermore, I'm seeing that the F5 monitors are reaching out on ports even lower than that (5612). [ Wed May 11 16:44:37 2016 830113 usecs]: Src IP: 10.251.12.3, Dst IP: 10.251.113.11, Src Port: 5929, Dst Port: 80, Src Intf: port-channel11 , Protocol: 6 The source IP from the F5 is it's own self-IP on a port-channel interface. I'm not sure if that matters, but could there be another location where it's pulling its own source port range?