RedHat 7.2: Network unreachable

Problem 1: After server reboot IP address didn't assign to interface and server was out of network

Solution: Even after configuring the interface observed netmask is 255.255.255.255 which was preventing to connect to network

Steps:

#ip address -add xx.xx.xx.xx dev ens123

#vi /etc/sysconfig/network-scripts/ifcfg-ens123
NETMASK=255.255.255.0
onboot=yes

#ifdown ens123

#ifup ens123

Problem 2: If you enable the iptables, it blocks the ssh. You can ssh to localhost from console but from outside you can't do ssh.

Solution: Disable the iptables or include the port

#systemctl stop iptables