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, administrator might want to monitor all remote ASA Firewalls with the SNMP server and syslog server located at a central site.
Configuring Cisco Devices to Use a Syslog Server
- When operating over a network, syslog uses a client-server architecture where the server listens on a well-known or registered port for protocol requests from clients. Historically the most common transport layer protocol for network logging has been User Datagram Protocol (UDP), with the server listening on port 514.
- Fastvue Syslog installs a Windows Service that listens for syslog messages and writes them to text. The service is configured via a web interface that runs on port 47279. The first time you access the web interface, you are presented with the options to set the log and archive paths, listening ports and a username/password for the web interface.
- Syslog stands for System Logging Protocol and is a standard protocol used to send system log or event messages to a specific server, called a syslog server.It is primarily used to collect various device logs from several different machines in a central location for monitoring and review.
- Centralize and simplify log message management across network devices and servers with Kiwi Syslog Server for Windows Free Edition. Download today.
Most Cisco devices use the syslog protocol to manage system logs and alerts. But unlike their PC and server counterparts, Cisco devices lack large internal storage space for storing these logs. To overcome this limitation, Cisco devices offer the following two options:
- Internal buffer-- The device's operating system allocates a small part of memory buffers to log the most recent messages. The buffer size is limited to few kilobytes. This option is enabled by default. However, when the device reboots, these syslog messages are lost.
- Syslog-- Use a UNIX-style SYSLOG protocol to send messages to an external device for storing. The storage size does not depend on the router's resources and is limited only by the available disk space on the external syslog server. This option is not enabled by default.
To enable syslog functionality in a Cisco network, you must configure the built-in syslog client within the Cisco devices.
Cisco devices use a severity level of warnings through emergencies to generate error messages about software or hardware malfunctions. The debugging level displays the output of debug commands. The Notice level displays interface up or down transitions and system restart messages. The informational level reloads requests and low-process stack messages. Club protector installation.
Configuring Cisco Routers for Syslog
To configure a Cisco IOS-based router for sending syslog messages to an external syslog server, follow the steps in Table 4-11 using privileged EXEC mode.
Table 4-11. Configuring Cisco Routers for Syslog
Step | Command | Purpose |
1 | Router# configure terminal | Enters global configuration mode. |
2 | Router(config)# service timestampstypedatetime [msec] [localtime] [show-timezone] | Instructs the system to timestamp syslog messages; the options for the type keyword are debug and log. |
3 | Router(config)#logginghost | Specifies the syslog server by IP address or host name; you can specify multiple servers. |
4 | Router(config)# logging traplevel | Specifies the kind of messages, by severity level, to be sent to the syslog server. The default is informational and lower. The possible values for level are as follows: Emergency: 0 Alert: 1 Critical: 2 Error: 3 Warning: 4 Notice: 5 Informational: 6 Debug: 7 Use the debug level with caution, because it can generate a large amount of syslog traffic in a busy network. |
5 | Router(config)# logging facilityfacility-type | Specifies the facility level used by the syslog messages; the default is local7. Possible values are local0, local1, local2, local3, local4, local5, local6, and local7. |
6 | Router(config)# End | Returns to privileged EXEC mode. |
7 | Router# show logging | Displays logging configuration. |
Example 4-12 prepares a Cisco router to send syslog messages at facility local3. Also, the router will only send messages with a severity of warning or higher. The syslog server is on a machine with an IP address of 192.168.0.30.
Example 4-12. Router Configuration for Syslog
Configuring a Cisco Switch for Syslog
To configure a Cisco CatOS-based switch for sending syslog messages to an external syslog server, use the privileged EXEC mode commands shown in Table 4-12.
Table 4-12. Configuring a Cisco Switch for Syslog
Step | Command | Purpose |
1 | Switch>(enable) set logging timestamp {enable | disable} | Configures the system to timestamp messages. |
2 | Switch>(enable) set logging serverip-address | Specifies the IP address of the syslog server; a maximum of three servers can be specified. |
3 | Switch>(enable) set logging server severityserver_severity_level | Limits messages that are logged to the syslog servers by severity level. |
4 | Switch>(enable) set logging server facilityserver_facility_parameter | Specifies the facility level that would be used in the message. The default is local7. Apart from the standard facility names listed in Table 4-1, Cisco Catalyst switches use facility names that are specific to the switch. The following facility levels generate syslog messages with fixed severity levels: Mvtec halcon license to drive. 5: System, Dynamic-Trunking-Protocol, Port-Aggregation-Protocol, Management, Multilayer Switching 4: CDP, UDLD 2: Other facilities |
5 | Switch>(enable) set logging server enable | Enables the switch to send syslog messages to the syslog servers. |
6 | Switch>(enable) Show logging | Displays the logging configuration. |
Example 4-13 prepares a CatOS-based switch to send syslog messages at facility local4. Also, the switch will only send messages with a severity of warning or higher. The syslog server is on a machine with an IP address of 192.168.0.30.
Example 4-13. CatOS-Based Switch Configuration for Syslog
Configuring a Cisco PIX Firewall for Syslog
Proactive monitoring of firewall logs is an integral part of a Netadmin's duties. The firewall syslogs are useful for forensics, network troubleshooting, security evaluation, worm and virus attack mitigation, and so on. The configuration steps for enabling syslog messaging on a PIX are conceptually similar to those for IOS- or CatOS-based devices. To configure a Cisco PIX Firewall with PIX OS 4.4 and above, perform the steps shown in Table 4-13 in privileged EXEC mode.
![Syslog Syslog](https://d1cy5sv9pggpkr.cloudfront.net/wp-content/uploads/visual-syslog-server.png)
Table 4-13. PIX Configuration for Syslog
Step | Command | Purpose |
1 | Pixfirewall# config terminal | Enters global configuration mode. |
2 | Pixfirewall(config)#logging timestamp | Specifies that each syslog message should have a timestamp value. |
3 | Pixfirewall(config)#logging host [interface connected to syslog server] ip_address [protocol/port] | Specifies a syslog server that is to receive the messages sent from the Cisco PIX Firewall. You can use multiple logging host commands to specify additional servers that would all receive the syslog messages. The protocol is UDP or TCP. However, a server can only be specified to receive either UDP or TCP, not both. A Cisco PIX Firewall only sends TCP syslog messages to the Cisco PIX Firewall syslog server. |
4 | Pixfirewall(config)#logging facilityfacility | Specifies the syslog facility number. Instead of specifying the name, the PIX uses a 2-digit number, as follows: local0 - 16 local1 - 17 local2 - 18 local3 - 19 local4 - 20 local5 - 21 local6 - 22 local7 - 23 The default is 20. |
5 | pixfirewall(config)#logging traplevel | Specifies the syslog message level as a number or string. The level that you specify means that you want that level and those values less than that level. For example, if level is 3, syslog displays 0, 1, 2, and 3 messages. Possible number and string level values are as follows: 0: Emergency; System-unusable messages 1: Alert; Take immediate action 2: Critical; critical condition 3: Error; error message 4: Warning; warning message 5: Notice; normal but significant condition 6: Informational: information message 7: Debug; debug messages and log FTP commands and WWW URLs |
6 | pixfirewall(config)#logging on | Starts sending syslog messages to all output locations. |
7 | pixfirewall(config)#no logging message <message id> | Specifies a message to be suppressed. |
8 | pixfirewall(config)#exit | Exits global configuration mode. |
Example 4-14 prepares the Cisco PIX Firewall to send syslog messages at facility local5 and severity debug and below to the syslog server. The Netadmin does not want the PIX to log message 111005. The syslog server has an IP address of 192.168.0.30.
Example 4-14. Configuring a Cisco PIX Firewall for Syslog
Ubuntu Syslog Server
For added reliability, the Cisco PIX Firewall can be configured to send syslog messages through TCP. Please note that if the syslog server disk is full, it can close the TCP connection. This will cause a denial of service because the Cisco PIX Firewall will stop all traffic until the syslog server disk space is freed. Both Kiwi Syslogd Server and PFSS offer this feature. Kiwi Syslogd has an alert mechanism to warn the Netadmin through e-mail or pager when the disk is nearing its capacity. The setting can be established from the Syslog Daemon Setup window, as shown in Figure 4-9, for Kiwi syslog configuration.
If the PIX stops because of a disk-full condition, you must first free some disk space. Then disable syslog messaging on the PIX by using the no logging hosthost command, followed by reenabling syslog messaging using the logging hosthost command.
Example 4-15 shows the configuration steps for a Cisco PIX Firewall to send syslog messages at TCP port 1468.
Example 4-15. PIX Configuration for TCP Syslog
Configuring a Cisco VPN Concentrator for Syslog
The Cisco VPN 3000 Series Concentrator provides an appliance-based solution for deploying VPN functionality across remote networks. VPN concentrators are often connected parallel to the firewalls, as shown earlier in Figure 4-1. The design simplifies the management of the network but creates security concerns. After a user has been authenticated through VPN concentrators, the user has complete access to the network. This makes a strong case for logging the messages from the VPN concentrator. To configure the Cisco VPN 3000 Series Concentrator for sending syslog messages, follow these steps:
- Log in to the VPN concentrator using a web browser.
- Navigate to the syslog server page by choosing Configuration > System > Events > Syslog Servers, as shown in Figure 4-12.
- On the Syslog Servers page, click the Add button (see Figure 4-12).
- Enter the IP address of the syslog server and select the facility level from the Facility drop-down menu, as shown in Figure 4-13. Save these settings and return to the Syslog Servers page by clicking the Add button. Figure 4-13 VPN Concentrator—Add Syslog Server
- To select the kind of messages that are to be sent to the syslog server, navigate to the General page by choosing Configuration > System > Events > General.
- On the General page, select an option from the Severity to Syslog drop-down menu, as shown in Figure 4-14, and click the Apply button. Figure 4-14 VPN Concentrator—General Configuration
- To save the configuration changes, click the Save Needed icon.
As configured in this example, the VPN concentrator is now ready to send syslog messages at facility local6, severity 1–5 to server 192.168.0.30.
Syslog Server Raspberry Pi
syslog
is a standardized protocol used to send Logs and events to the Log server. syslog
can be used in different platforms like Linux, Windows, Unix, Applications etc. In this tutorial we will look the default syslog port and secure syslog port and some examples about how to change this port number.syslog
is a protocol which is defined in RFC 5424 and RFC 3164 . The port number is defined as 514
with UDP protocol for syslog services. There is also a recommendation about source port to be UDP 514
too. This port number also registered by IANA to the syslog
protocol which means other applications can not use 514 as official default port.As stated previously the default port of syslog is
UDP 514
as we know UDP
is unreliable protocol according to TCP. syslog can be used for important security logs which can not tolerate log loss. We can use TCP
which is far more reliable than UDP with the same port number 514.In some cases strict security standards like PCI-DSS and HIPAA needs the logs to be securely transferred. Also the security policy of the company may requires also this type of the transport security. In this case we can use
TCP 6514
port. This is not an official port but its de facto standard of the implementation.As an example we can collect syslogs in Cisco devices with the following commands and configuration.
First we need to enable logging and start syslog service with the following command.
Syslog Server Linux
then we will specify the log server IP address. But we can also specify the protocol and port number explicitly. This is not mandatory and if not specified the default
udp/514
will be set.