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Cisco PIX 500 Series Security Appliances

PIX/ASA 7.x and later with Syslog Configuration Example

Cisco - PIX/ASA 7.x with Syslog Configuration Example

Document ID: 63884

Updated: Aug 21, 2007

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Introduction

This sample configuration demonstrates how to configure PIX/ASA Security Appliance 7.x with syslog.

PIX 7.0 has introduced very granular filtering techniques to allow only certain specified syslog messages to be presented. The Basic Syslog section of this document demonstrates a traditional syslog configuration. The Advanced Syslog section of this document shows the new syslog features in 7.0.

Refer to Cisco Security Appliance System Log Messages Guide, Version 7.x for the complete system log messages guide.

Refer to Setting Up PIX Syslog for more information on how to configure syslog in Cisco Secure PIX Software Releases 4.0.x.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

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

  • PIX 515E with PIX Software version 7.0

  • Cisco Adaptive Security Device Manager (ASDM) version 5.01

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.

Note: Refer to ASA 8.2: Configure Syslog using ASDM for more information for similar configuration details using ASDM version 6.2 and later.

Conventions

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

Basic Syslog

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

Use these commands to enable logging, view logs, and view configuration settings.

  • logging enable—Enables the transmission of syslog messages to all output locations.

  • no logging enable—Disables logging to all output locations.

  • show logging—Lists the contents of the syslog buffer and the current logging configuration.

PIX can send syslog messages to various destinations. Use the commands in these sections to specify the location to which messages should be sent:

Internal Buffer

logging buffered severity_level 

External software or hardware is not required when you store the syslog messages in the PIX internal buffer. Use the show logging to view the stored syslog messages.

Syslog Message Server

logging host interface_name ip_address [tcp[/port] | udp[/port]] [format emblem] 

    logging trap severity_level 

    logging facility number

A server that runs a syslog application is required in order to send syslog messages to an external host. PIX sends syslog on UDP port 514 by default.

E-mail Address

logging mail severity_level 

    logging recipient-address email_address

    logging from-address email_address

    smtp-server ip_address

An SMTP server is required when you send the syslog messages in e-mails. Correct configuration on the SMTP server is necessary in order to ensure that you can successfully relay e-mails from the PIX to the specified e-mail client.

Console

logging console severity_level 

Console logging enables syslog messages to display on the PIX console (tty) as they occur. Use this command when you debug problems or when there is minimal load on the network. Do not use this command when the network is busy as it can degrade performance.

Telnet/SSH Session

logging monitor severity_level 

    terminal monitor

Logging monitor enables syslog messages to display as they occur when you access the PIX console with Telnet or SSH.

ASDM

logging asdm severity_level 

ASDM also has a buffer that can be used to store syslog messages. Use the show logging asdm command in order to display the content of the ASDM syslog buffer.

SNMP Management Station

logging history severity_level 

    snmp-server host [if_name] ip_addr

    snmp-server location text

    snmp-server contact text

    snmp-server community key

    snmp-server enable traps 

Users need an existing functional Simple Network Management Protocol (SNMP) environment in order to send syslog messages using SNMP.

Refer to Commands for Setting and Managing Output Destinations for a complete reference on the commands you can use to set and manage output destinations

Refer to Messages Listed by Severity Level for messages listed by severity level.

Example 1

This output shows a sample configuration for logging into the console with the severity level of debugging.

logging enable

logging buffered debugging

This is sample output.

%PIX|ASA-6-308001: console enable password incorrect for number tries (from 10.1.1.15)

Configure Basic Syslog using ASDM

This procedure demonstrates the ASDM configuration for all available syslog destinations followed by the configuration for Example 1.

  1. Go to the ASDM Home window.

  2. Choose Configuration > Features > Properties > Logging > Logging Setup.

  3. Check Enable logging in order to enable syslogs.

    pix70-syslog-1.gif

  4. Choose Syslog Servers in Logging and click Add in order to add a syslog server.

  5. Enter the syslog server details in the Add Syslog Server box and choose OK when you are done.

    pix70-syslog-2.gif

  6. Choose E-Mail Setup in Logging in order to send syslog messages to e-mails.

  7. Specify the source e-mail address in the Source E-Mail Address box and choose Add in order to configure the destination e-mail address of the e-mail recipients and the message severity level. Click OK when you are done.

    pix70-syslog-3.gif

  8. Choose Device Administration, choose SMTP, and enter the server IP address in order to specify the SMTP server IP address.

    pix70-syslog-4.gif

  9. Choose SNMP in order to specify the address of the SNMP management station and properties.

    pix70-syslog-5.gif

  10. Choose Add in order to add an SNMP management station. Enter the SNMP host details and click OK.

    pix70-syslog-6.gif

  11. Click Properties under Configuration and choose Logging Filters in Logging in order to select the destination of the syslog messages.

  12. Choose the desired Logging Destination and click Edit.

    For this procedure, Example 1 logging buffered debugging is used.

  13. Choose Internal Buffer and click Edit.

    pix70-syslog-7.gif

  14. Choose Filter on severity and choose Debugging from the drop-down menu. Click OK when you are done.

    pix70-syslog-8.gif

  15. Click Apply after you return to the Logging Filters window.

    pix70-syslog-9.gif

Send Syslog Messages Over a VPN to a Syslog Server

In either the simple site-to-site VPN design or the more complicated hub-and-spoke design, people sometimes want to monitor all the PIX Firewalls with the Simple Network Management Protocol (SNMP) server and syslog server located at a central site.

In order to configure the site-to-site IPsec VPN configuration, refer to PIX/ASA 7.x Simple PIX-to-PIX VPN Tunnel using ASDM Configuration Example. Apart from the VPN configuration, you have to configure the SNMP and the interesting traffic for the syslog server in both the central and local site.

pix2pix-vpn-pix70-1.gif

Central PIX Configuration


!--- This access control list (ACL) defines IPsec interesting traffic.
!--- This line covers traffic between the LAN segment behind two PIXes.
!--- It also includes the SNMP/syslog traffic between the SNMP/syslog server
!--- and the network devices located on the Ethernet segment behind the PIX 515.

access-list 101 permit ip 172.22.1.0 255.255.255.0 172.16.1.0 255.255.255.0


!--- This lines covers SNMP (TCP/UDP port - 161), SNMP TRAPS(TCP/UDP port - 162) 
!--- and syslog traffic (UDP port - 514) from SNMP/syslog server  
!--- to the outside interface of the remote PIX.
 

 
access-list 101 permit tcp host 172.22.1.5 host 10.20.20.1 eq 161
access-list 101 permit udp host 172.22.1.5 host 10.20.20.1 eq 161
access-list 101 permit tcp host 172.22.1.5 host 10.20.20.1 eq 162
access-list 101 permit udp host 172.22.1.5 host 10.20.20.1 eq 162
access-list 101 permit udp host 172.22.1.5 host 10.20.20.1 eq 514
logging on
logging trap debugging
logging history debugging


!--- Define logging host information.


logging facility 16
logging host inside 172.22.1.5



!--- Define the SNMP configuration.


snmp-server host inside 172.22.1.5
snmp-server community test
snmp-server enable traps

Remote PIX Configuration


!--- This ACL defines IPsec interesting traffic.
!--- This line covers traffic between the LAN segment behind two PIXes.
!--- It also covers the SNMP/syslog traffic between the SNMP/syslog server
!--- and the network devices located on the Ethernet segment behind PIX 515.


access-list 101 permit ip 172.16.1.0 255.255.255.0 172.22.1.0 255.255.255.0

!--- This lines covers SNMP (TCP/UDP port - 161), SNMP TRAPS (TCP/UDP port - 162) and 
!--- syslog traffic (UDP port - 514) sent from this PIX outside 
!--- interface to the SYSLOG server.



access-list 101 permit tcp host 10.20.20.1 host 172.22.1.5 eq 161
access-list 101 permit udp host 10.20.20.1 host 172.22.1.5 eq 161
access-list 101 permit tcp host 10.20.20.1 host 172.22.1.5 eq 162
access-list 101 permit udp host 10.20.20.1 host 172.22.1.5 eq 162
access-list 101 permit udp host 10.20.20.1 host 172.22.1.5 eq 514

!--- Define syslog server.


logging facility 23
logging host outside 172.22.1.5


!--- Define SNMP server.


snmp-server host outside 172.22.1.5
snmp-server community test
snmp-server enable traps

Refer to Monitoring Cisco Secure PIX Firewall Using SNMP and Syslog Through VPN Tunnel for more information on how to configure PIX 6.x.

Advanced Syslog

PIX 7.0 provides several mechanisms that enable you to configure and manage syslog messages in groups. These mechanisms include message severity level, message class, message ID, or a custom message list that you create. With the use of these mechanisms, you can enter a single command that applies to small or large groups of messages. When you set up syslogs this way, you are able to capture the messages from the specified message group and no longer all the messages from the same severity.

Use the Message List

Use the message list in order to include only the interested syslog messages by severity level and ID into a group, then associate this message list with the desired destination.

Complete these steps in order to configure a message list.

  1. Enter the logging list message_list | level severity_level [class message_class] command in order to create a message list that includes messages with a specified severity level or message list.

  2. Enter the logging list message_list message syslog_id-syslog_id2 command in order to add additional messages to the message list just created.

  3. Enter the logging destination message_list command in order to specify the destination of the message list created.

Example 2

Issue these commands in order to create a message list, which includes all the severity 2 (critical) messages with the addition of message 611101 to 611323, and also have them sent to the console:

logging list my_critical_messages level 2
logging list my_critical_messages message 611101-611323
logging console my_critical_messages 

ASDM Configuration

This procedure shows an ASDM configuration for Example 2 with the use of the message list.

  1. Choose Event Lists under Logging and click Add in order to create a message list.

    pix70-syslog-10.gif

  2. Enter the name of the message list in the Name box. In this case my_critical_messages is used. Click Add under Event Class/Severity Filters.

    pix70-syslog-11.gif

  3. Choose the Event Class and Severity from the drop-down menus.

    In this case, choose All and Critical respectively. Click OK when you are done.

    pix70-syslog-12.gif

  4. Click Add under the Message ID Filters if additional messages are required.

    In this case, you need to put in messages with ID 611101-611323.

    pix70-syslog-13.gif

  5. Put in the ID range in the Message IDs box and click OK.

    pix70-syslog-14.gif

  6. Go back to the Logging Filters menu and choose Console as the destination.

  7. Click Use event list and choose my_critical_messages from the drop- down menu. Click OK when you are done.

    pix70-syslog-15.gif

  8. Click Apply after you return to the Logging Filters window.

    pix70-syslog-16.gif

    This completes the ASDM configurations using message list as shown in Example 2.

Use the Message Class

Use the message class in order to send all messages associated with a class to the specified output location. When you specify a severity level threshold, you can limit the number of messages sent to the output location.

logging class message_class destination | severity_level 

Example 3

Enter this command in order to send all ca class messages with a severity level of emergencies or higher to the console.

logging class ca console emergencies

ASDM Configuration

This procedures shows the ASDM configurations for Example 3 with the use of the message list.

  1. Choose the Logging Filters menu and choose Console as the destination.

  2. Click Disable logging from all event classes.

  3. Under the Syslogs from Specific Event Classes, choose the Event Class and Severity you want to add.

    This procedure uses ca and Emergencies respectively.

  4. Click Add in order to add this into the message class and click OK.

    pix70-syslog-17.gif

  5. Click Apply after you return to the Logging Filters window.

    Console now collects the ca class message with severity level Emergencies as shown on the Logging Filters window.

    pix70-syslog-18.gif

    This completes the ASDM configuration for Example 3.

    Refer to Messages Listed by Severity Level for a list of the log message severity levels.

Log ACL ACE Hits

Add log to each access list element (ACE) you wish in order to log in order to log when an access list is hit. Use this syntax:

access-list id {deny | permit protocol} {source_addr source_mask}  
{destination_addr destination_mask} {operator port} {log}

Example:

pixfirewall(config)#access-list 101 line 1 extended permit icmp any any log

When the log option is specified, it generates syslog message 106100 for the ACE to which it is applied. Syslog message 106100 is generated for every matching permit or deny ACE flow that passes through the PIX Firewall. The first-match flow is cached. Subsequent matches increment the hit count displayed in the show access-list command.

Unable to connect to remote host:, Connection timed out for the ACE, and new 106100 messages are generated at the end of the interval defined by interval seconds if the hit count for the flow is not zero. The default access list logging behavior, which is the log keyword not specified, is that if a packet is denied, then message 106023 is generated, and if a packet is permitted, then no syslog message is generated.

An optional syslog level (0 - 7) can be specified for the generated syslog messages (106100). If no level is specified, the default level is 6 (informational) for a new ACE. If the ACE already exists, then its existing log level remains unchanged. If the log disable option is specified, access list logging is completely disabled. No syslog message, including message 106023, is generated. The log default option restores the default access list logging behavior.

Complete these steps in order to enable the syslog message 106100 to view in the console output:

  1. Issue the logging enable command in order to enable transmission of system log messages to all output locations. You must set a logging output location in order to view any logs.

  2. Issue the logging message <message_number> level <severity_level> command in order to set the severity level of a specific system log message.

    In this case, issue the logging message 106100 command to enable the message 106100.

  3. Issue the logging console message_list | severity_level command in order to enable system log messages to display on the Security Appliance console (tty) as they occur. Set the severity_level from 1 to 7 or use the level name. You can also specify which messages are sent with the message_list variable.

  4. Issue the show logging message command in order to display a list of system log message messages that have been modified from the default setting, which are messages that have been assigned a different severity level and messages that have been disabled.

    This is sample output of the show logging message command:

    pixfirewall#show logging message 106100 
    syslog 106100: default-level informational (enabled)
    pixfirewall# %PIX-7-111009: User 'enable_15' executed cmd: show logging mess 106
    100

Capture VPN Traffic Syslog Messages

Use the logging list command in order to capture the syslog for LAN-to-LAN and Remote access IPsec VPN messages alone. This example captures all VPN (IKE and IPsec) class system log messages with debugging level or higher.

Example:

hostname(config)#logging enable
hostname(config)#logging timestamp
hostname(config)#logging list my-list level debugging class vpn
hostname(config)#logging trap my-list
hostname(config)#logging host inside 192.168.1.1

Note: The logging list command is supported on 7.2(1) and later.

Verify

There is currently no verification procedure available for this configuration.

Troubleshoot

  1. If you do not receive the syslog 304001 messages, then make sure that the inspect http command is enabled on the ASA.

  2. If you want to deny a specific syslog message to be sent to syslog server, then you must use the command as shown.

    hostname(config)#no logging message <syslog_id>

    Refer to the logging message command for more information.

%ASA-3-201008: Disallowing new connections

The %ASA-3-201008: Disallowing new connections. error message is seen when ASA is unable to contact syslog server and no new connections are allowed.

Solution

This message appears when you have enabled TCP system log messaging and the syslog server cannot be reached, or when you use Cisco ASA Syslog Server (PFSS) and the disk on the Windows NT system is full. Complete these steps in order to resolve this error message:

  • Disable TCP system log messaging if it is enabled.

  • If you use PFSS, free up space on the Windows NT system where PFSS resides.

  • Also, make sure that the syslog server is up and you can ping the host from the Cisco ASA console.

  • Restart TCP system message logging in order to allow traffic.

If the syslog server goes down and the TCP logging is configured either use the logging permit-hostdown command or switch to UDP logging.

Related Information

Updated: Aug 21, 2007
Document ID: 63884