PuTTy connection is not possible!!

[turbo67]

Have you tried to change the port on which sshd listens?
: Yes, I have tried to change the port 8012 into 22022, but it also failed.
If so then did you tell selinux about the new port number? Did you open the port in firewalld?
So, I did make the selinux config option disabled. I also open the port in firewalld.

I don't know what the problem is...
Thanks anyway!!

[poky]

1. Make sure you have a current version of PuTTY.
Go to section Connection > SSH > Auth > GSSAPI and disable the option Attempt GSSAPI authentication.

2. Try a ssh client other than PuTTY - for example, MobaXterm.

3. Make sure you have a current version of CentOS:
yum update

4. Check, if the IP that the Centos has, is not the same as another machine on the network.

5. For Root login, edit the sshd_config file in /etc/ssh/sshd_config and then restart sshd:
..................
# Authentication:
#LoginGraceTime 2m
# If it's set to without-password then root login is allowed but only using a key, not using a password
PermitRootLogin yes
#StrictModes yes
.................

6. Check the status of SELinux on your system:
sestatus

getenforce

Disable SELinux Temporarily:
setenforce 0
(enable setenforce 1)

Restart sshd service:
systemctl restart sshd

[turbo67]

1. Make sure you have a current version of PuTTY.: Yes, the PuTTy version is 0.7 which is the latest version.

Go to section Connection > SSH > Auth > GSSAPI and disable the option Attempt GSSAPI authentication.
: It also failed.
2. Try a ssh client other than PuTTY - for example, MobaXterm.
: I can reach other server which is on the same network with this server using PuTTy.

3. Make sure you have a current version of CentOS: Yes, it is a current version.
yum update

4. Check, if the IP that the Centos has, is not the same as another machine on the network.
: The IP is not the same as another server.

5. For Root login, edit the sshd_config file in /etc/ssh/sshd_config and then restart sshd:
..................
# Authentication:
#LoginGraceTime 2m
# If it's set to without-password then root login is allowed but only using a key, not using a password
PermitRootLogin yes
#StrictModes yes
.................
: Already edited.

6. Check the status of SELinux on your system:
sestatus

getenforce

Disable SELinux Temporarily:
setenforce 0
(enable setenforce 1)

Restart sshd service:
systemctl restart sshd
Already disabled.

Thank you for your kind reply.

[turbo67]

I have two tcp ports on the server, 22 and 22022.
Running "nc -z serverip 8012" shows "Connection to serverip 22022 port [tcp/*] succeeded!", and
running "nc -z serverip 22" shows "Connection to serverip 22 port [tcp/ssh] succeeded!".
Could it a clue about my ssh connection problem?