Configuring Cisco Devices to Use a Syslog Server
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:
A syslog server is a logging server that allows for the centralized collection of syslog messages, known as events, from a variety of networking devices such as routers, switches, and firewalls, in addition to servers running a variety of operating systems. 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.
- Sep 11, 2019 Another free syslog server software, WhatsUp Gold Syslog Server is a straightforward way to manage your syslog needs. It monitors syslog messages and provides real-time views into message data as well as filters to help you sort through the approximately 6,000,000 messages it can process per hour.
- Jan 15, 2020 A comprehensive, feature-rich application, Syslog Watcher from SnmpSoft is a Windows-based dedicated syslog server that collects and analyzes syslogs from any number of network hosts and servers. (The free version allows up to 5 sources, while the professional license lets you collect from an unlimited number of sources.).
- 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.
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 How do i update widevine drm for mac os. | 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: 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.
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 | Global tis keygen for mac. 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
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.
![Syslog Server Syslog Server](https://cdn.vidyard.com/thumbnails/284003/dVJ_JMfldqsmPhGz-oH-RA_play_button.jpg)
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.
System Logging Protocol (Syslog) is a way network devices can use a standard message format to communicate with a logging server. It was designed specifically to make it easy to monitor network devices. Devices can use a Syslog agent to send out notificationmessages under a wide range of specific conditions.
These log messages include a timestamp, a severity rating, a device ID (including IP address), and information specific to the event. Though it does have shortcomings, the Syslog protocol is widely applied because it is simple to implement, and is fairlyopen-ended, allowing for a lot of different proprietary implementations, and thus the ability to monitor almost any connected device.
Syslog works on all flavors of Unix, Linux, and other *nix, as well as MacOS. Windows-based servers don’t support Syslog natively, but many third-party tools are available to allow Windows devices to communicate with a Syslog server.
Note: the term “Syslog” can variously refer to the actual server process or “daemon” (the Syslog daemon is called syslogd when someone is being precise), the message format, and the protocol. This happens with widely used systemsthat have been around for a while and have multiple uses.
The Necessity of Logging
A big advantage of syslog is that the log server can monitor a vast number of syslog events via log files. Routers, switches, firewalls, and servers can generate log messages, as well as many printers and other devices.
The syslog server receives, categorizes, and stores log messages for analysis, maintaining a comprehensive view of what is going on everywhere on the network. Without this view, devices can malfunction unexpectedly, and outages can be hard to trace.
![Syslog server raspberry pi Syslog server raspberry pi](https://i.ytimg.com/vi/e7ns_gXoQA4/maxresdefault.jpg)
Syslog Messages
Syslog messages are sent via User Datagram Protocol (UDP), port 514. UDP is what is called a connectionless protocol, so messages aren’t acknowledged or guaranteed to arrive. This can be a drawback but also leaves the system simple and easyto manage.
Star trek elite force mod. Syslog messages are often in a human-readable format but don’t need to be. In its header, each message has a priority level, which is a combination of a code for the process of the device creating the message and a severity level. The processcodes, called “facilities”, are derived from UNIX. Severity levels range from 0 for emergency and 1 for immediate attention required, down to 6 for informational and 7 for debug messages.
Together, these two codes allow for quick classification of Syslog messages.
Collecting and Managing Data
Because of the large amount of Syslog data that results from retaining all of these messages, a Syslog server needs a large database.
It also needs management and filtering software that enables the server to automatically generate alerts, alarms, and notifications. Filtering allows a sysadmin to easily call up files from a certain source, such as a firewall, for a specifiedtime period.
On-screen popups or remote text messages can keep a sysadmin aware of any divergence from normal functioning. If there is some concern about a particular device, thresholds can be set lower, to more closely monitor messages of lower severity.
The Syslog data can be used in a variety of other ways, for example for detailed reporting, as well as the generation of diagrams to clarify the structure of the network.
Security Information and Event Management (SIEM) software provides a way to track, integrate, and analyze the vast amount of log data Syslog collects. Originally focused on compliance reporting, SIEM is now more widely used and can be a useful adjunctto Syslog.
How Syslog Differs From SNMP
Simple Network Management Protocol (SNMP) is another protocol for network device monitoring. SNMP works differently, getting most of its information by polling devices. Syslog servers can often accept SNMP data, particularly SNMP traps,that is, SNMP-enabled devices send without being polled.
SNMP is best for constrained situations with predictable conditions, while Syslog is both wider in scale and less constrained in format, and covers many different types of events.
Differing flavors of Syslog
In addition to Syslog, there are rsyslog and syslog-ng. Syslog is the original recipe, dating back to the early 1980s, while the other two are slightly differing flavors that have come out since.
Syslog-ng was begun in 1988 and adds some new filtering and encryption functions. Its syntax is not directly derived from syslog and so a syslog-ng server and syslog-ng configuration are somewhat different. You can learn more about howto install syslog-ng here.
Rsyslog dates from 2004, and is derived directly from Syslog, so it can be easily used as a replacement for it, since a syslog.conf file can be used in place of rsyslog.conf . Much like syslog-ng it also has improved ability to parseunstructured data and ship it to various destinations.
Syslog Server Download
Both syslog-ng and rsyslog can also use TCP, TLS, and RELP, in addition to UDP.