topic static PAT problem on ASA 7.2 in Network Security

static PAT problem on ASA 7.2

jasonww04 — Tue, 12 Mar 2019 02:50:17 GMT

Here are the relevant parts of my config:

interface Vlan1

nameif inside

security-level 100

ip address 172.18.67.1 255.255.255.0

interface Vlan2

nameif outside

security-level 0

ip address 71.x.x.x 255.255.255.0

interface Ethernet0/0

switchport access vlan 2

same-security-traffic permit inter-interface

same-security-traffic permit intra-interface

access-list NAT extended permit ip 172.18.67.0 255.255.255.0 10.11.0.0 255.255.0.0

access-list NAT extended permit ip 172.18.67.0 255.255.255.0 10.41.0.0 255.255.0.0

access-list Port_Forwarding-ACL extended permit tcp any host 172.18.67.2 eq 3389

global (outside) 1 interface

nat (inside) 0 access-list NAT

nat (inside) 1 0.0.0.0 0.0.0.0

static (inside,outside) tcp interface 3389 172.18.67.2 3389 netmask 255.255.255.255

access-group Port_Forwarding-ACL in interface outside

route outside 0.0.0.0 0.0.0.0 71.169.11.1 1

Here is a packet tracer output:

eas-ny-pinn# packet-tracer input outside tcp 1.1.1.1 3389 172.18.67.2 3389

Phase: 1

Type: FLOW-LOOKUP

Subtype:

Result: ALLOW

Config:

Additional Information:

Found no matching flow, creating a new flow

Phase: 2

Type: ROUTE-LOOKUP

Subtype: input

Result: ALLOW

Config:

Additional Information:

in 172.18.67.0 255.255.255.0 inside

Phase: 3

Type: ACCESS-LIST

Subtype: log

Result: ALLOW

Config:

access-group Port_Forwarding-ACL in interface outside

access-list Port_Forwarding-ACL extended permit tcp any host 172.18.67.2 eq 3389

Additional Information:

Phase: 4

Type: IP-OPTIONS

Subtype:

Result: ALLOW

Config:

Additional Information:

Phase: 5

Type: HOST-LIMIT

Subtype:

Result: ALLOW

Config:

Additional Information:

Phase: 6

Type: NAT

Subtype: rpf-check

Result: DROP

Config:

static (inside,outside) tcp interface 3389 172.18.67.2 3389 netmask 255.255.255.255

match tcp inside host 172.18.67.2 eq 3389 outside any

static translation to 71.169.11.10/3389

translate_hits = 0, untranslate_hits = 6

Additional Information:

Result:

input-interface: outside

input-status: up

input-line-status: up

output-interface: inside

output-status: up

output-line-status: up

Action: drop

Drop-reason: (acl-drop) Flow is denied by configured rule

Why is this failing?

static PAT problem on ASA 7.2

Jouni Forss — Thu, 10 Oct 2013 16:30:14 GMT

Hi,

Its failing because you are targetting the local IP address of the destination host in the "packet-tracer" command.

If someone on the external network were to connect to this host then the destination IP address would be that of your "outside" interface.

Use the "outside" interface IP address as the destination IP in the "packet-tracer" command and post that output if there is still a problem with it

- Jouni

static PAT problem on ASA 7.2

jasonww04 — Thu, 10 Oct 2013 19:21:11 GMT

This is what I get now.

eas-ny-pinn# packet-tracer input outside tcp 1.1.1.1 3389 71.169.11.10 3389

Phase: 1

Type: FLOW-LOOKUP

Subtype:

Result: ALLOW

Config:

Additional Information:

Found no matching flow, creating a new flow

Phase: 2

Type: UN-NAT

Subtype: static

Result: ALLOW

Config:

static (inside,outside) tcp interface 3389 172.18.67.2 3389 netmask 255.255.255.255

match tcp inside host 172.18.67.2 eq 3389 outside any

static translation to 71.169.11.10/3389

translate_hits = 0, untranslate_hits = 18

Additional Information:

NAT divert to egress interface inside

Untranslate 71.169.11.10/3389 to 172.18.67.2/3389 using netmask 255.255.255.255

Phase: 3

Type: ACCESS-LIST

Subtype:

Result: DROP

Config:

Implicit Rule

Additional Information:

Result:

input-interface: outside

input-status: up

input-line-status: up

output-interface: inside

output-status: up

output-line-status: up

Action: drop

Drop-reason: (acl-drop) Flow is denied by configured rule

Re: static PAT problem on ASA 7.2

Jouni Forss — Thu, 10 Oct 2013 19:24:36 GMT

Hi,

Try adding

access-list Port_Forwarding-ACL extended permit tcp any interface outside eq 3389

Then test the actual connection again and "packet-tracer" if you want.

- Jouni

static PAT problem on ASA 7.2

jasonww04 — Thu, 10 Oct 2013 19:54:43 GMT

That fixed it. I'm always screwing up ACLs on interfaces when it comes to NAT. No one outside the network is trying to reach the private IP, that's what the NAT does.