Contents

Introduction

Prerequisites

Requirements

Components Used

Related Products

Background Information

Configure

Network Diagram

Configure a Routed Interface and a Subinterface

Step 1. Configure the Logical Interface

Step 2. Configure the Physical Interface

FTD Routed Interface Operation

FTD Routed Interface Overview

Verify

Trace a Packet on FTD Routed Interface

Related Information

Introduction

This document describes the configuration, verification, and operation of an Inline Pair Interface on a Firepower Threat Defense (FTD) appliance.

Prerequisites

Requirements

There are not specific requirements for this document.

Components Used

The information in this document is based on these software and hardware versions:

- ASA5512-X - FTD code 6.1.0.x

- Firepower Management Center (FMC) - code 6.1.0.x

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

Related Products

This document can also be used with these hardware and software versions:

- ASA5506-X, ASA5506W-X, ASA5506H-X, ASA5508-X, ASA5516-X

- ASA5512-X, ASA5515-X, ASA5525-X, ASA5545-X, ASA5555-X

- FPR2100, FPR4100, FPR9300

- VMware (ESXi), Amazon Web Services (AWS), Kernel-based Virtual Machine (KVM)

- FTD software code 6.2.x and later

Background Information

The Firepower Threat Defense (FTD) provides two Deployment modes and six Interface modes as shown in this image:

Note: You can mix interface modes on a single FTD appliance.

High level overview of the various FTD deployment and interface modes:

FTD interface mode

FTD Deployment mode

Description

Traffic can be dropped

Routed

Routed

Full LINA engine and Snort-engine checks

Yes

Switched

Transparent

Full LINA engine and Snort-engine checks

Yes

Inline Pair

Routed or Transparent

Partial LINA engine and full Snort-engine checks

Yes

Inline Pair with Tap

Routed or Transparent

Partial LINA engine and full Snort-engine checks

No

Passive

Routed or Transparent

Partial LINA engine and full Snort-engine checks

No

Passive (ERSPAN)

Routed

Partial LINA engine and full Snort-engine checks

No

Configure

Network Diagram

Configure a Routed Interface and a Subinterface

Configure subinterface G0/0.201 and interface G0/1 as per these requirements:

Interface

G0/0.201

G0/1

Name

INSIDE

OUTSIDE

Security Zone

INSIDE_ZONE

OUTSIDE_ZONE

Description

INTERNAL

EXTERNAL

Sub interface ID

201

-

VLAN ID

201

-

IPv4

192.168.201.1/24

192.168.202.1/24

Duplex/Speed

Auto

Auto

Solution

Step 1. Configure the Logical Interface

Navigate to Devices > Device Management, select the appropriate device and select the Edit icon:

Select Add Interfaces > Sub Interface:

Configure the subinterface settings as per requirements:

Interface IP settings:

Under the physical interface (GigabitEthernet0/0) specify the Duplex and Speed settings:

Enable the physical interface (G0/0 in this case):

Step 2. Configure the Physical Interface

Edit the GigabitEthernet0/1 physical interface as per requirements:

- For Routed interface the Mode is: None

- The Name is equivalent to the ASA interface nameif

- On FTD all interfaces have security level = 0

- same-security-traffic is not applicable on FTD. Traffic between FTD interfaces (inter) and (intra) is allowed by default

Select Save and Deploy.

Verification

From the FMC GUI:

From the FTD CLI:

> show interface ip brief

Interface                  IP-Address      OK? Method Status                Protocol

GigabitEthernet0/0         unassigned      YES unset  up                    up

GigabitEthernet0/0.201     192.168.201.1   YES manual up                    up

GigabitEthernet0/1         192.168.202.1   YES manual up                    up

GigabitEthernet0/2         unassigned      YES unset  administratively down down

GigabitEthernet0/3         unassigned      YES unset  administratively down down

GigabitEthernet0/4         unassigned      YES unset  administratively down down

GigabitEthernet0/5         unassigned      YES unset  administratively down down

Internal-Control0/0        127.0.1.1       YES unset  up                    up

Internal-Data0/0           unassigned      YES unset  up                    up

Internal-Data0/1           unassigned      YES unset  up                    up

Internal-Data0/2           169.254.1.1     YES unset  up                    up

Management0/0              unassigned      YES unset  up                    up

> show ip

System IP Addresses:

Interface                Name                   IP address      Subnet mask     Method

GigabitEthernet0/0.201   INSIDE                 192.168.201.1   255.255.255.0   manual

GigabitEthernet0/1       OUTSIDE                192.168.202.1   255.255.255.0   manual

Current IP Addresses:

Interface                Name                   IP address      Subnet mask     Method

GigabitEthernet0/0.201   INSIDE                 192.168.201.1   255.255.255.0   manual

GigabitEthernet0/1       OUTSIDE                192.168.202.1   255.255.255.0   manual

FMC GUI and FTD CLI correlation:

> show interface g0/0.201

Interface GigabitEthernet0/0.201 "INSIDE", is up, line protocol is up

Hardware is i82574L rev00, BW 1000 Mbps, DLY 10 usec

VLAN identifier 201

Description: INTERNAL

MAC address a89d.21ce.fdea, MTU 1500

IP address 192.168.201.1, subnet mask 255.255.255.0

Traffic Statistics for "INSIDE":

1 packets input, 28 bytes

1 packets output, 28 bytes

0 packets dropped

> show interface g0/1

Interface GigabitEthernet0/1 "OUTSIDE", is up, line protocol is up

Hardware is i82574L rev00, BW 1000 Mbps, DLY 10 usec

Auto-Duplex(Full-duplex), Auto-Speed(1000 Mbps)

Input flow control is unsupported, output flow control is off

Description: EXTERNAL

MAC address a89d.21ce.fde7, MTU 1500

IP address 192.168.202.1, subnet mask 255.255.255.0

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 pause input, 0 resume input

0 L2 decode drops

1 packets output, 64 bytes, 0 underruns

0 pause output, 0 resume output

0 output errors, 0 collisions, 12 interface resets

0 late collisions, 0 deferred

0 input reset drops, 0 output reset drops

input queue (blocks free curr/low): hardware (511/511)

output queue (blocks free curr/low): hardware (511/511)

Traffic Statistics for "OUTSIDE":

0 packets input, 0 bytes

0 packets output, 0 bytes

0 packets dropped

1 minute input rate 0 pkts/sec,  0 bytes/sec

1 minute output rate 0 pkts/sec,  0 bytes/sec

1 minute drop rate, 0 pkts/sec

5 minute input rate 0 pkts/sec,  0 bytes/sec

5 minute output rate 0 pkts/sec,  0 bytes/sec

5 minute drop rate, 0 pkts/sec

>

FTD Routed Interface Operation

Verify the FTD packet flow when Routed interfaces are in use.

Solution

FTD Architectural overview

A high-level overview of the FTD data plane:

This picture shows some of the checks that occur within each engine:

Key points

- The bottom checks correspond to the FTD LINA engine Data Path

- The checks inside the blue box correspond to the FTD Snort engine instance

FTD Routed Interface Overview

- Available only in Routed Deployment

- Traditional L3 firewall deployment

- One or more physical or logical (VLAN) routable interfaces

- Allows features like NAT or Dynamic Routing protocols to be configured

- Packets are forwarded based on Route Lookup and next hop is resolved based on ARP Lookup

- Actual traffic can be dropped

- Full LINA engine checks are applied along with full Snort engine checks

The last point can be visualized as follows:

Verify

Trace a Packet on FTD Routed Interface

Network Diagram

Use packet-tracer with the these parameters to see the applied policies:

Input interface

INSIDE

Protocol/Service

TCP port 80

Source IP

192.168.201.100

Destination IP

192.168.202.100

Solution

When a Routed interface is used the packet is processed in a similar way to a classic ASA Routed interface. Checks like Route Lookup, Modular Policy Framework (MPF), NAT, ARP lookup etc take place in the LINA engine Data Path. Additionally, if the Access Control Policy requires so, the packet is inspected by the Snort engine (one of the Snort instances) where a verdict is generated and returned back to the LINA engine:

> packet-tracer input INSIDE tcp 192.168.201.100 11111 192.168.202.100 80

Phase: 1

Type: ROUTE-LOOKUP

Subtype: Resolve Egress Interface

Result: ALLOW

Config:

Additional Information:

found next-hop 192.168.202.100 using egress ifc  OUTSIDE

Phase: 2

Type: ACCESS-LIST

Subtype: log

Result: ALLOW

Config:

access-group CSM_FW_ACL_ global

access-list CSM_FW_ACL_ advanced permit ip any any rule-id 268437505

access-list CSM_FW_ACL_ remark rule-id 268437505: ACCESS POLICY: FTD5512 - Default/1

access-list CSM_FW_ACL_ remark rule-id 268437505: L4 RULE: DEFAULT ACTION RULE

Additional Information:

This packet will be sent to snort for additional processing where a verdict will be reached

Phase: 3

Type: CONN-SETTINGS

Subtype:

Result: ALLOW

Config:

class-map class-default

match any

policy-map global_policy

class class-default

set connection advanced-options UM_STATIC_TCP_MAP

service-policy global_policy global

Additional Information:

Phase: 4

Type: NAT

Subtype: per-session

Result: ALLOW

Config:

Additional Information:

Phase: 5

Type: IP-OPTIONS

Subtype:

Result: ALLOW

Config:

Additional Information:

Phase: 6

Type: NAT

Subtype: per-session

Result: ALLOW

Config:

Additional Information:

Phase: 7

Type: IP-OPTIONS

Subtype:

Result: ALLOW

Config:

Additional Information:

Phase: 8

Type: FLOW-CREATION

Subtype:

Result: ALLOW

Config:

Additional Information:

New flow created with id 11336, packet dispatched to next module

Result:

input-interface: INSIDE

input-status: up

input-line-status: up

output-interface: OUTSIDE

output-status: up

output-line-status: up

Action: allow

>

Note: In phase 4 the packet is checked against a TCP map called UM_STATIC_TCP_MAP. This is the default TCP Map on FTD.

firepower# show run all tcp-map

!

tcp-map UM_STATIC_TCP_MAP

no check-retransmission

no checksum-verification

exceed-mss allow

queue-limit 0 timeout 4

reserved-bits allow

syn-data allow

synack-data drop

invalid-ack drop

seq-past-window drop

tcp-options range 6 7 allow

tcp-options range 9 18 allow

tcp-options range 20 255 allow

tcp-options selective-ack allow

tcp-options timestamp allow

tcp-options window-scale allow

tcp-options mss allow

tcp-options md5 clear

ttl-evasion-protection

urgent-flag allow

window-variation allow-connection

!

>

Related Information

- Cisco Firepower Threat Defense Configuration Guide for Firepower Device Manager, Version 6.1

- Install and Upgrade Firepower Threat Defense on ASA 55xx-X devices

- Cisco Secure Firewall Threat Defense

- Cisco Technical Support & Downloads