Cisco ASA Cli

Static NAT (SNAT)

object network obj-192.168.1.100 
host 192.168.1.100 
nat (inside,outside) static 192.166.1.101 dns

PAT

Allow outside connections targeting TCP port 80 to redirect to internal port 8080.

object network obj-192.166.1.101-srv_8080
host 192.166.1.101
nat (inside,outside) static 192.166.1.101 service tcp 8080 http

DNAT

In the example bellow, the subnet will be on a port channel named inside2 and will have a obj-group called net-local2

interface port-channel 150
nameif inside2
security-level 100
ip address 172.10.10.0 255.255.255.0
object-group network net-local2
network-object 172.10.10.0 255.255.255.0

after-auto Inserts the rule at the end of section.
You can translate all addresses on the source interface by specifying source dynamic any mapped_obj

nat (inside2,outside) after-auto source dynamic net-local2 interface dns

PAT connections will be visible in show xlate

fw1# show xlate
TCP PAT from inside2:172.10.10.11/51995 to outside:199.199.199.100/51995 flags riD
idle 0:05:37 timeout 0:00:30

For more advanced configs, refer to article below:

https://www.cisco.com/c/en/us/td/docs/security/asa/asa-command-reference/I-R/cmdref2/n.html

Configuring Static PAT as a Twice NAT/Manual NAT

object network local-192.168.1.100
host 192.168.1.100

object network external-2.2.2.2
host 2.2.2.2

object service https
service tcp source eq https

object service tcp_8443
service tcp source eq 8443
 
nat (inside,outside) source static local-192.168.1.100 external-2.2.2.2 service tcp_8443 https

DHCP Server

dhcpd address 10.20.106.240-10.20.106.253 inside
dhcpd dns 8.8.8.8 8.8.4.4
dhcpd enable inside

ASDM

asdm image disk0:/asdm-X.bin
http server enable 8080
http <whitelist-ip> 255.255.255.0 OUTSIDE
username admin password PASSWORD privilege 15
https://<asa ip>:8080

Allow non-connected subnets

arp permit-nonconnected

The ASA ARP cache only contains entries from directly-connected subnets by default. You can enable the ARP cache to also include non-directly-connected subnets. We do not recommend enabling this feature unless you know the security risks. This feature could facilitate denial of service (DoS) attack against the ASA; a user on any interface could send out many ARP replies and overload the ASA ARP table with false entries.

You may want to use this feature if you use:

  • Secondary subnets.

  • Proxy ARP on adjacent routes for traffic forwarding.

Route LAN to remote subnet on physical port

interface GigabitEthernet1/8
  description remote
  no nameif
  no security-level
  no ip address

interface GigabitEthernet1/8.100
  description Public VLAN 100 remote
  vlan 100
  nameif remote
  no security-level
  ip address 192.168.1.2 255.255.255.0
    
object network local-net
  subnet 192.168.2.0 255.255.255.0
    
object network remote-net
  subnet 192.168.3.0 255.255.255.0
    
access-list inbound extended permit ip object local-net object remote-net
nat (inside,remote) source static local-net local-net destination static remote-net remote-net

route remote 192.168.3.0 255.255.255.0 192.168.1.1 1

In this example you will be able to connect to "192.168.3.0/24" from your local "192.168.2.0/24" subnet using the 192.168.1.2 port, the remote port will be on the same vlan using the IP 192.168.1.1

Object Groups ASA

object-group service http-https tcp
port-object eq www
port-object eq https
object-group network webservers
network-object host 192.168.1.101
network-object host 192.168.1.102
network-object host 192.168.1.103
access-list OUTSIDE-IN extended permit tcp any object-group webservers object-group http-https
access-group OUTSIDE-IN in interface outside

packet-tracer

packet-tracer input inside icmp 192.168.1.100 8 0 8.8.8.8
packet-tracer input outside tcp 8.8.8.8 80 192.168.1.100 80

Backup/Restore

Create a Backup 

copy running-config disk0:/backup-2017-00-00

Restore a backup

copy disk0:/backup-2017-08-18 startup-config
reload

Allow FTP passive ports

The firewall will block this data communication because it will start from a different source port (20 instead of 21). The purpose therefore of the inspect ftp command on the Cisco ASA is to listen for the initial Command FTP traffic (on port 21) and dynamically open a secondary Data connection between FTP server and client (from port 20). This will allow FTP communication to work. If you disable FTP inspection with the no inspect ftp command, outbound users can start connections only in passive mode, and all inbound FTP is disabled.

policy-map global_policy
 class inspection_default
  no inspect ftp

Mitigating attack traffic

DEFINE TRAFFIC

First of all we define which traffic the MPF policy will be applied to. In the example below we exclude the host 8.8.8.8 whilst inspecting all other traffic.

access-list mpf-policy-acl extended permit ip any any
CREATE CLASS-MAP

Next we assign the previously created access-list to a class-map.

class-map mpf-policy
match access-list mpf-policy-acl
CREATE POLICY-MAP

Then a policy-map is created and the necessary connection limits defined.

policy-map mpf-policy-map
class mpf-policy
set connection conn-max 9500
set connection embryonic-conn-max 5000
set connection per-client-embryonic-max 100
set connection per-client-max 300

Allow LAN management over VPN

management-access inside
nat (inside,any) source static obj-LANSUBNET obj-LANSUBNET destination static obj-VPNSUBNET obj-VPNSUBNET route-lookup
http <VPNSUBNET> 255.255.255.0 inside
ssh <VPNSUBNET> 255.255.255.0 inside

Failover

To run on the Standby FW

failover active

Licensing Info

Different ASA models have different licensing options. To see what the limits of the active license, use the following:

sh version

https://www.cisco.com/c/en/us/support/security/asa-5500-series-next-generation-firewalls/products-command-reference-list.html

https://wiki.myhypervisor.ca/books/networking/page/cisco-asa-site-to-site

https://www.cisco.com/c/en/us/support/security/asa-5500-series-next-generation-firewalls/products-installation-and-configuration-guides-list.html

https://www.cisco.com/c/en/us/support/security/asa-5500-series-next-generation-firewalls/products-configuration-examples-list.html

 

 

 


Revision #33
Created Thu, Jun 29, 2017 1:51 AM by Dave
Updated Thu, Feb 13, 2020 3:44 AM by Dave