ASA 8.3 and Later: Set SSH/Telnet/HTTP Connection Timeout using MPF Configuration Example

Introduction

This document provides a sample configuration for Cisco Adaptive Security Appliance (ASA) with version 8.3(1) and later of a timeout that is specific to a particular application such as SSH/Telnet/HTTP, as opposed to one that applies to all applications. This configuration example uses the Modular Policy Framework (MPF) which was introduced in Cisco Adaptive Security Appliance (ASA) version 7.0. Refer to Using Modular Policy Framework for more information.

In this sample configuration, the Cisco ASA is configured to allow the workstation (10.77.241.129) to Telnet/SSH/HTTP to the remote server (10.1.1.1) behind the router. A separate connection timeout to Telnet/SSH/HTTP traffic is also configured. All other TCP traffic continues to have the normal connection timeout value associated with timeout conn 1:00:00.

Refer to PIX/ASA 7.x and later/FWSM: Set SSH/Telnet/HTTP Connection Timeout using MPF Configuration Example for the same configuration on Cisco ASA with versions 8.2 and earlier.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document is based on Cisco ASA Security Appliance Software version 8.3(1) with Adaptive Security Device Manager (ASDM) 6.3.

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, make sure that you understand the potential impact of any command.

Conventions

Refer to the Cisco Technical Tips Conventions for more information on document conventions.

Configure

In this section, you are presented with the information to configure the features described in this document.

Note: Use the Command Lookup Tool (registered customers only) in order to obtain more information on the commands used in this section.

Network Diagram

This document uses this network setup:

Note: The IP addressing schemes used in this configuration are not legally routable on the Internet. They are RFC 1918 addresses, which have been used in a lab environment.

Configurations

This document uses these configurations:

• CLI Configuration

• ASDM Configuration

Note: These CLI and ASDM configurations are applicable to the Firewall Service Module (FWSM).

CLI Configuration

ASA Version 8.3(1) 
!
hostname ASA
domain-name nantes-port.fr
enable password S39lgaewi/JM5WyY level 3 encrypted
enable password 2KFQnbNIdI.2KYOU encrypted
passwd 1mZfSd48bl0UdPgP encrypted
no names

dns-guard
!
interface Ethernet0/0
 nameif outside
 security-level 0
 ip address 192.168.200.1 255.255.255.0 
!
interface Ethernet0/1
 nameif inside
 security-level 100
ip address 10.77.241.142 255.255.255.0
 

boot system disk0:/asa831-k8.bin
ftp mode passive
dns domain-lookup outside


!--- Creates an object called DM_INLINE_TCP_1. This defines the traffic !--- that has to be matched in the class map.


object-group service DM_INLINE_TCP_1 tcp
 port-object eq www
 port-object eq ssh
 port-object eq telnet

access-list outside_mpc extended permit tcp host 10.77.241.129 any object-group DM_INLINE_TCP_1 


pager lines 24
mtu inside 1500
mtu outside 1500
no failover
no asdm history enable
arp timeout 14400
nat (inside) 0 access-list inside_nat0_outbound
access-group 101 in interface outside

route outside 0.0.0.0 0.0.0.0 192.168.200.2 1
timeout xlate 3:00:00


!--- The default connection timeout value of one hour is applicable to !--- all other TCP applications.

timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00
timeout mgcp-pat 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout uauth 0:05:00 absolute
timeout tcp-proxy-reassembly 0:01:00
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
telnet timeout 5
ssh timeout 5
console timeout 0
!


!--- Define the class map Cisco-class in order !--- to classify Telnet/ssh/http traffic when you use Modular Policy Framework !--- to configure a security feature. !--- Assign the parameters to be matched by class map.


class-map Cisco-class
 match access-list outside_mpc

class-map inspection_default
 match default-inspection-traffic
!
!
policy-map global_policy
 class inspection_default
  inspect dns maximum-length 512
  inspect ftp
  inspect h323 h225
  inspect h323 ras
  inspect netbios
  inspect rsh
  inspect rtsp
  inspect skinny
  inspect esmtp
  inspect sqlnet
  inspect sunrpc
  inspect tftp
  inspect sip
  inspect xdmcp


!--- Use the pre-defined class map Cisco-class in the policy map. 


policy-map Cisco-policy


!--- Set the connection timeout under the class mode where !--- the idle TCP (Telnet/ssh/http) connection is disconnected. !--- There is a set value of ten minutes in this example. !--- The minimum possible value is five minutes.


 class Cisco-class
  set connection timeout idle 0:10:00 reset
!
!
service-policy global_policy global


!--- Apply the policy-map Cisco-policy on the interface. !--- You can apply the service-policy command to any interface that !--- can be defined by the nameif command.

service-policy Cisco-policy interface outside
end

ASDM Configuration

Complete these steps in order to set up TCP connection timeout for Telnet, SSH and HTTP traffic using ASDM as shown.

Note: Refer to Allowing HTTPS Access for ASDM for basic settings in order to access the PIX/ASA through ASDM.

1. Choose Configuration > Firewall > Service Policy Rules and click Add in order to configure the Service Policy rule as shown.

   

2. From the Add Service Policy Rule Wizard - Service Policy window, choose the radio button next to Interface under the Create a Service Policy and Apply To section. Now choose the desired interface from the drop-down list and provide a Policy Name. The policy name used in this example is Cisco-policy. Then, click Next.

   

3. Create a class map name Cisco-class and check the Source and Destination IP address (uses ACL) check box in the Traffic Match Criteria. Then, click Next.

   

4. From the Add Service Policy Rule Wizard - Traffic Match - Source and Destnation Address window, choose the radio button next to Match and then provide the source and the destination address as shown. Click the drop-down button next to Service to choose the required services.

   

5. Select the required services such as telnet, ssh and http. Then, click OK.

   

6. Configure Timeouts. Click Next.

   

7. Choose Connection Settings in order to set up the TCP Connection Timeout as 10 minutes. Also, check the Send reset to TCP endpoints before timeout check box. Click Finish.

   

8. Click Apply in order to apply the configuration to the Security Appliance.

   This completes the configuration.

   

Ebryonic Timeout

An embryonic connection is the connection that is half open or, for example, the three-way handshake has not been completed for it. It is defined as SYN timeout on the ASA. By default, the SYN timeout on the ASA is 30 seconds. This is how to configure Embryonic Timeout:

access-list emb_map extended permit tcp any any 
 
class-map emb_map
match access-list emb_map
  
policy-map global_policy
class emb_map
set connection timeout embryonic 0:02:00
 
service-policy global_policy global

Troubleshoot

If you find that the connection timeout does not work with the MPF, then check the TCP initiation connection. The issue can be a reversal of the source and destination IP address, or a misconfigured IP address in the access list does not match in the MPF to set the new timeout value or to change the default timeout for the application. Create an access list entry (source and destination) in accordance with the connection initiation in order to set the connection timeout with MPF.

Related Information

• Cisco Adaptive Security Device Manager
• Cisco ASA 5500 Series Adaptive Security Appliances
• Requests for Comments (RFCs)
• Technical Support & Documentation - Cisco Systems