There is no option -P in RHEL8. You need to use the -w option followed by the argument sysctl -w net.ipv4.ip_forward=1 NOTE: No space before or after "=" sign.

[root@station ~]# sysctl -a | grep net.ipv4.ip_forward net.ipv4.ip_forward = 0 net.ipv4.ip_forward_update_priority = 1 net.ipv4.ip_forward_use_pmtu = 0 [root@station ~]# sysctl -w net.ipv4.ip_forward=1 net.ipv4.ip_forward = 1 [root@station ~]# sysctl -a | grep net.ipv4.ip_forward net.ipv4.ip_forward = 1 net.ipv4.ip_forward_update_priority = 1 net.ipv4.ip_forward_use_pmtu = 0 [root@station ~]#

echo "net.ipv4.ip_forward = 1" > /etc/sysctl.d/ipforward.conf systemctl reboot

echo net.ipv4.ip_forward=1 >> /etc/sysctl.conf sysctl -p

echo " net.ipv4.ip_forward = 1" >> /etc/sysctl.conf

vi /etc/sysctl.conf net.ipv4.ip_forward = 1

# grep ip_forward /etc/sysctl.d/* /etc/sysctl.d/60-gce-network-security.conf:net.ipv4.ip_forward=0 # vi /etc/sysctl.d/60-gce-network-security.conf net.ipv4.ip_forward=0 # sysctl -w net.ipv4.ip_forward=1