Se deben deshabilitar servicios innecesarios, protocolos inseguros, AAA y varias cosas más que no todo el mundo conoce.
Ahora bien, IOS a partir de la versión 12.3 nos provee un feature llamado Auto Secure, que es una especie de asistente que puede hacer el hardening del equipo en forma interactiva (tal cual el modo setup que se accede al no tener la startup-config).
Para usarlo en la forma más básica,los pasos son los siguientes:
Router#auto secure
--- AutoSecure Configuration ---
*** AutoSecure configuration enhances the security of
the router, but it will not make it absolutely resistant
to all security attacks ***
AutoSecure will modify the configuration of your device.
All configuration changes will be shown. For a detailed
explanation of how the configuration changes enhance security
and any possible side effects, please refer to Cisco.com for
Autosecure documentation.
At any prompt you may enter '?' for help.
Use ctrl-c to abort this session at any prompt.
Gathering information about the router for AutoSecure
Is this router connected to internet? [no]: yes
Enter the number of interfaces facing the internet [1]: 1
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 192.168.1.1 YES manual up up
GigabitEthernet0/0 192.168.2.1 YES manual up up
GigabitEthernet1/0 192.168.3.1 YES manual up up
GigabitEthernet2/0 192.168.4.1 YES manual up up
SSLVPN-VIF0 unassigned NO unset up up
Enter the interface name that is facing the internet: Ethernet0/0
Securing Management plane services...
Disabling service finger
Disabling service pad
Disabling udp & tcp small servers
Enabling service password encryption
Enabling service tcp-keepalives-in
Enabling service tcp-keepalives-out
Disabling the cdp protocol
Disabling the bootp server
Disabling the http server
Disabling the finger service
Disabling source routing
Disabling gratuitous arp
Is SNMP used to manage the router? [yes/no]: yes
SNMPv1 & SNMPv2c are unsecure, try to use SNMPv3
Here is a sample Security Banner to be shown
at every access to device. Modify it to suit your
enterprise requirements.
Authorized Access only
This system is the property of So-&-So-Enterprise.
UNAUTHORIZED ACCESS TO THIS DEVICE IS PROHIBITED.
You must have explicit permission to access this
device. All activities performed on this device
are logged. Any violations of access policy will result
in disciplinary action.
Enter the security banner {Put the banner between
k and k, where k is any character}:
#
The access to this device or attached networks
is prohibited without express written permission.
Violators will be prosecuted to the fullest extent
of both civil and criminal law.
We don't like you.
Go away!
#
Configuration of local user database
Enter the username: ariel
Enter the password:
Confirm the password:
Configuring AAA local authentication
Configuring Console, Aux and VTY lines for
local authentication, exec-timeout, and transport
Securing device against Login Attacks
Configure the following parameters
Blocking Period when Login Attack detected: 5
Maximum Login failures with the device: 3
Maximum time period for crossing the failed login attempts: 5
Configure SSH server? [yes]: yes
Enter the hostname: Router-Internet
Enter the domain-name: capaocho.net
Configuring interface specific AutoSecure services
Disabling the following ip services on all interfaces:
no ip redirects
no ip proxy-arp
no ip unreachables
no ip directed-broadcast
no ip mask-reply
Disabling mop on Ethernet interfaces
Securing Forwarding plane services...
Configure CBAC Firewall feature? [yes/no]: yes
This is the configuration generated:
no service finger
no service pad
no service udp-small-servers
no service tcp-small-servers
service password-encryption
service tcp-keepalives-in
service tcp-keepalives-out
no cdp run
no ip bootp server
no ip http server
no ip finger
no ip source-route
no ip gratuitous-arps
no ip identd
banner motd ^C
The access to this device or attached networks
is prohibited without express written permission.
Violators will be prosecuted to the fullest extent
of both civil and criminal law.^C
security passwords min-length 6
security authentication failure rate 10 log
username ariel password 7 021501590A151B284D40
aaa new-model
aaa authentication login local_auth local
line con 0
login authentication local_auth
exec-timeout 5 0
transport output telnet
line aux 0
login authentication local_auth
exec-timeout 10 0
transport output telnet
line vty 0 4
login authentication local_auth
transport input telnet
login block-for 5 attempts 3 within 5
hostname Router-Internet
ip domain-name capaocho.net
crypto key generate rsa general-keys modulus 1024
ip ssh time-out 60
ip ssh authentication-retries 2
line vty 0 4
transport input ssh telnet
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
logging facility local2
logging trap debugging
service sequence-numbers
logging console critical
logging buffered
interface Ethernet0/0
no ip redirects
no ip proxy-arp
no ip unreachables
no ip directed-broadcast
no ip mask-reply
no mop enabled
interface GigabitEthernet0/0
no ip redirects
no ip proxy-arp
no ip unreachables
no ip directed-broadcast
no ip mask-reply
no mop enabled
interface GigabitEthernet1/0
no ip redirects
no ip proxy-arp
no ip unreachables
no ip directed-broadcast
no ip mask-reply
no mop enabled
interface GigabitEthernet2/0
no ip redirects
no ip proxy-arp
no ip unreachables
no ip directed-broadcast
no ip mask-reply
no mop enabled
ip inspect audit-trail
ip inspect dns-timeout 7
ip inspect tcp idle-time 14400
ip inspect udp idle-time 1800
ip inspect name autosec_inspect cuseeme timeout 3600
ip inspect name autosec_inspect ftp timeout 3600
ip inspect name autosec_inspect http timeout 3600
ip inspect name autosec_inspect rcmd timeout 3600
ip inspect name autosec_inspect realaudio timeout 3600
ip inspect name autosec_inspect smtp timeout 3600
ip inspect name autosec_inspect tftp timeout 30
ip inspect name autosec_inspect udp timeout 15
ip inspect name autosec_inspect tcp timeout 3600
ip access-list extended autosec_firewall_acl
permit udp any any eq bootpc
deny ip any any
interface Ethernet0/0
ip inspect autosec_inspect out
ip access-group autosec_firewall_acl in
!
end
Apply this configuration to running-config? [yes]:
Applying the config generated to running-config
The name for the keys will be: Router-Internet.capaocho.net
% The key modulus size is 1024 bits
% Generating 1024 bit RSA keys, keys will be non-exportable...[OK]
Router-Internet#
Aunque las cosas automáticas no son siempre la mejor salida, se puede decir que este feature seguramente va a configurar varias cosas que no tenemos habilitadas.
Nos vemos en la próxima.
4 comentarios:
Gracias por este y otros articulos de seguridad que he leido ultimamente en tu blog(IOS resielent)
He echo el curso CCNAsec y me estoy preparando la certificacion.
Ando algo "parado" con los firewall CBAC¿A ver si me podeis echar una mano?
La principal duda que me surge es donde colocarlo. He visto ejemplos de Cisco(los incluidos en PT y los de la curricula)que lo coloca en el interfaz interno y direccion entrante, y otros(como en este articulo y en el libro de Cisco del CCNAsec de Michael Watkins) donde lo coloca en el interfaz saliente y direccion saliente.
¿Me podrias aclarar porque tanto "lio"?¿Acaso las dos soluciones estan bien?
Espero haberme explicado con claridad.
Gracias de antemano y un saludo Ariel:D
Y no existe una receta única...
Todo depende de tu escenario.
Saludos
Gracias por tu rapida respuesta Ariel:D
Información muy útil
Muchas gracias !!
Publicar un comentario