CentOS prohibits root users from remotely logging on via telnet or ssh

AIX

Only the root user can be logged on using su, and direct remote login is prohibited.
1. Disable telnet Logon
Smit chuser
-> Root
-> User can login REMOTELY (rsh, tn, rlogin) = false

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Disable telnet/ftp
Stopsrc-t telnet
Stopsrc-t ftp

Enable telnet \ ftp
Startsrc-t telnet
Startsrc-t ftp

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2. disable ssh logon.
Vi/etc/ssh/sshd_config
PermitRootLogin no
Restart the ssh service
Stopsrc-s sshd
Startsrc-s sshd

Run the following command to view the service:

Lssrc-a | grep ssh

LINUX

1. in linux, remote login by telnet is disabled for root users by default.

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Set to telnet to linux using the root user
By default, the ROOT user cannot connect to the Linux operating system through telnet, which is also insecure. However, technically speaking, this can be achieved.
# Mv/etc/securetty. bak
Save and exit.
You can use the ROOT user to log on to the Linux system via telnet.

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2. disable ROOT remote SSH Logon:
# Vi/etc/ssh/sshd_config
Set PermitRootLogin yes
Change to PermitRootLogin no
Restart sshd service
# Service sshd restart

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List LINUX boot items:
# Chkconfig -- list
List running LINUX services:
# Service -- status-all