Tag: centos 7

How to enable iptables in CentOS 7

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Just use the following commands to disable firewalld and enable the good old iptables in any CentOS 7 based VPS or server:

[root@test2 ~]# systemctl stop firewalld

[root@test2 ~]# systemctl mask firewalld
Created symlink from /etc/systemd/system/firewalld.service to /dev/null.

[root@test2 ~]# yum install -y iptables iptables-services
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.centos.org
* extras: mirror.centos.org
* updates: mirror.centos.org
base | 3.6 kB 00:00:00
extras | 3.4 kB 00:00:00
updates | 3.4 kB 00:00:00
Package iptables-1.4.21-24.1.el7_5.x86_64 already installed and latest version
Resolving Dependencies
–> Running transaction check
—> Package iptables-services.x86_64 0:1.4.21-24.1.el7_5 will be installed
–> Finished Dependency Resolution

Dependencies Resolved

=========================================================================================================================================
Package Arch Version Repository Size
=========================================================================================================================================
Installing:
iptables-services x86_64 1.4.21-24.1.el7_5 updates 51 k

Transaction Summary
=========================================================================================================================================
Install 1 Package

Total download size: 51 k
Installed size: 25 k
Downloading packages:
iptables-services-1.4.21-24.1.el7_5.x86_64.rpm | 51 kB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : iptables-services-1.4.21-24.1.el7_5.x86_64 1/1
Verifying : iptables-services-1.4.21-24.1.el7_5.x86_64 1/1

Installed:
iptables-services.x86_64 0:1.4.21-24.1.el7_5

Complete!
[root@test2 ~]#

[root@test2 ~]# systemctl enable iptables
Created symlink from /etc/systemd/system/basic.target.wants/iptables.service to /usr/lib/systemd/system/iptables.service.
[root@test2 ~]#
[root@test2 ~]# systemctl start iptables

How to update SSH Port in CentOS 7

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Update SSH Port in CentOS 7

Here are few simple steps on how to update SSH Port in CentOS 7 VPS or Dedicated Server

Edit the SSHD configuration file :

nano -w /etc/ssh/sshd_config

(if nano is not installed use any other text editor or install it with yum -y install nano)

and change the Port number from 22 to any custom port you choose :

e.g. Port 18989

Make sure to even remove the # mark before Port

Save the config file

SELinux is enabled by default in CentOS 7 so you need to even inform SELinux to change the SSH Port else it won’t allow you to restart SSHD with new Port.

To run semanage for updating SSHD Port you nee to first install policycoreutils, install it with :

yum -y install policycoreutils-python

now update SeLinux policy to allow new port for SSH service. to do this, run below :

semanage port -a -t ssh_port_t -p tcp 18989

now you need to update Firewall policy to allow new SSH Port, to do this run below :

firewall-cmd –permanent –zone=public –add-port=18989/tcp
firewall-cmd –reload
systemctl restart sshd.service

SSHD Port is now updated, you can now connect to your new SSH Port: 18989