Contents

Introduction

- Requirements

- Components Used

- Defaults

Configure Connection Timeout

- ASDM

- ASA CLI

Verify

References

Introduction

This document describes configuring Connection timeout on ASA and ASDM for a specific application protocol such as HTTP, HTTPS, FTP, or any other protocols. Connection timeout is the period of inactivity after which a firewall or network device terminates an idle connection to free up resources and enhance security. In advance, the first question is: What is the requirement for this configuration? If applications have proper TCP keepalive settings, configuring connection timeout on a firewall is often unnecessary. However, if applications lack proper keepalive settings or timeout configurations, in that case configuring connection timeout on a firewall is crucial for managing resources, enhancing security, improving network performance, ensuring compliance, and optimizing user experience.

Requirements

Cisco recommends that you have knowledge of these topics:

- Access Control List (ACL)

- Service Policy

- Connection Timeout

Components Used

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

- ASA 9.17(1)

- ASDM 7.17(1)

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.

Defaults

Note: Default timeout

The default embryonic timeout is 30 seconds.

The default half-closed idle timeout is 10 minutes.

The default dcd max_retries value is 5.

The default dcd retry_interval value is 15 seconds.

The default tcp idle timeout is 1 hour.

The default udp idle timeout is 2 minutes.

The default icmp idle timeout is 2 seconds.

The default sip idle timeout is 30 minutes.

The default sip_media idle timeout is 2 minutes.

The default esp and ha idle timeout is 30 seconds.

For all other protocols, the default idle timeout is 2 minutes.

To never time out, enter 0:0:0.

Configure Connection Timeout

ASDM

If a particular traffic has a connection table, it has a specific idle timeout; for example, in this article, we change the connection timeout for DNS traffic.

Here are many options to configure the Connection Timeout for specific traffic, considering the network diagram of this traffic:

Client ----- [Interface: MNG] Firewall [Interface: OUT] ----- Server

There is the possibility of assigning an ACL to the interface.

Step1: Create an ACL

We can assign Source, Destination, or Service

ASDM > Configuration > Firewall > Advanced > ACL Manager

Step2: Create Service Policy rule

You can skip the last step if you already have your ACL, or you can assign one of those parameters (source, Destination, or Service) to the Service Policy to the Interface.

ASDM > Configuration > Firewall > Service Policy rules

Step3: Create traffic class

There is a possibility to choose Source and Destination IP Address (uses ACL)

Step4: Assign ACL

In this step, you can assign the existing ACL or select match conditions (source, Destination, or Service)

Step5: Configure the Idle Timeout parameter

Based on valid format HH:MM:SS configure the Idle timeout.

Clear connections for that particular traffic:

#clear conn addressEnter an IP address or a range of IP addresses

#clear conn protocolEnter this keyword to clear SCP/TCP/UDP conns only

ASA CLI

You can configure all these settings via the CLI:

ACL:

access-list DNS_TIMEOUT extended permit udp any any eq domain

Class-map:

class-map MNG-class

match access-list DNS_TIMEOUT

Policy-map:

policy-map MNG-policy

class MNG-class

set connection timeout idle 0:37:00

Apply the Policy-map on the Interface:

service-policy MNG-policy interface MNG

Verify

Tip: If we run this command, we can confirm the connection timeout of the DNS traffic:

ASA CLI > enable mode > show conn long

Example: show conn long address 192.168.1.1

UDP MNG: 192.168.1.1/53 (192.168.1.1/53) OUT: 10.10.10.30/63327 (10.10.10.30/63327), flags - , idle 17s, uptime 17s, timeout 2m0s, bytes 36

UDP MNG: 192.168.1.1/53 (192.168.1.1/53) OUT: 10.10.10.30/62558 (10.10.10.30/62558), flags - , idle 40s, uptime 40s, timeout 2m0s, bytes 36

Then, after configuration, we can confirm the idle timeout configuration:

Example: show conn long address 192.168.1.1

UDP MNG: 192.168.1.1/53 (192.168.1.1/53) OUT: 10.10.10.30/63044 (10.10.10.30/63044), flags - , idle 8s, uptime 8s, timeout 37m0s, bytes 37

UDP MNG: 192.168.1.1/53 (192.168.1.1/53) OUT: 10.10.10.30/63589 (10.10.10.30/63589), flags - , idle 5s, uptime 5s, timeout 37m0s, bytes 41

References

What Are Connection Settings