Configurar SSH Server en CenTos

En este pequeño articulo vamos a ver como configurar un servidor ssh para poder acceder remotamente a nuestro server.

Es necesario tener OpenSSH, aunque normalmente se instala de forma predeterminada, incluso si se instaló CentOS Minimal, así que no es necesario instalarlo de nuevo.

Puedes iniciar sesión con la autenticación de contraseña por defecto, pero debes cambiar algunos ajustes de seguridad.

[root@tuserver ~]# nano /etc/ssh/sshd_config

# line 48: uncomment and change ( prohibit root login remotely )
PermitRootLogin no

# line 77: uncomment
PermitEmptyPasswords no
PasswordAuthentication yes

# Reiniciamos el servicio
[root@tuserver ~]# systemctl restart sshd

[root@tuserver ~]# nano /etc/ssh/sshd_config

# line 48: uncomment and change ( prohibit root login remotely )

PermitRootLogin no

# line 77: uncomment

PermitEmptyPasswords no

PasswordAuthentication yes

# Reiniciamos el servicio

[root@tuserver ~]# systemctl restart sshd

Si está corriendo el Firewall, debemos concederle permisos… por defecto el puerto 22/TCP (conviene cambiarlo por otro).

[root@tuserver ~]# firewall-cmd --add-service=ssh --permanent 
success

[root@tuserver ~]# firewall-cmd --reload 
success

[root@tuserver ~]# firewall-cmd --add-service=ssh --permanent

success

[root@tuserver ~]# firewall-cmd --reload

success

Ahora por seguridad cambiamos el puerto por defecto (22) por otro, por ejemplo 3850.

Accedemos con:

nano /etc/ssh/sshd_config

1	nano /etc/ssh/sshd_config

Nos aparecerá algo similar a:

#       $OpenBSD: sshd_config,v 1.98 2016/02/17 05:29:04 djm Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# The default requires explicit activation of protocol 1
#Protocol 2

# $OpenBSD: sshd_config,v 1.98 2016/02/17 05:29:04 djm Exp $

# This is the sshd server system-wide configuration file. See

# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with

# OpenSSH is to specify options with their default value where

# possible, but leave them commented. Uncommented options override the

# default value.

#Port 22

#AddressFamily any

#ListenAddress 0.0.0.0

#ListenAddress ::

# The default requires explicit activation of protocol 1

#Protocol 2

Modificamos y descomentamos la linea del puerto:

#       $OpenBSD: sshd_config,v 1.98 2016/02/17 05:29:04 djm Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

Port 3850
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# The default requires explicit activation of protocol 1
#Protocol 2