In a previous post, I've shown how you can log the changes in interactive user's privilege level. With the Cisco IOS Login Enhancements (introduced in IOS release 12.3(4)T, integrated in 12.4), you can also log all login successes and failures, even when using local user database (a similar functionality was previously achievable only when using central TACACS+ or RADIUS server).

The configuration commands to enable terminal access logging are login on-success log and login on-failure log. You can also specify that you want send SNMP traps in these circumstances (with the trap option) or that you only want to log every Nth attempt with the every n option.

The logging userinfo configuration command introduced in IOS release 12.3T (integrated into 12.4) starts logging of all changes in user privilege levels (as requested by enable or disable commands).

When I was still teaching Cisco courses, we were telling the students that the order of network statements in an OSPF process was important if their ranges were overlapping; the first network statement that matched an interface IP address would place that interface in the corresponding area. This is no longer true; Cisco IOS now properly handles overlapping network area configuration commands.

Consider the following example:

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I always hate it when Cisco IOS asks me for things I've already supplied in a command line, the most notable case being the copy command. For example, if you supply the complete source and destination file name in the command line, IOS still insists on asking you all the same questions (at least filling in the parameters I've supplied in the command line):

fw#copy system:running-config tftp://10.0.0.2/fw-test
Source filename [running-config]?
Address or name of remote host [10.0.0.2]?
Destination filename [fw-test]?
!!
2009 bytes copied in 0.604 secs (3326 bytes/sec)

You can disable the annoying questions with the file prompt quiet configuration command (the default value of this parameter is noisy).

As part of Configuraton Change Notification and Logging feature, Cisco IOS stores the most recent configuration commands in a circular buffer and (optionally) sends them to syslog streams.

This feature is configured under the archive configuration mode with the log config command, which brings you to yet another configuration mode where you can fine-tune the parameters (they are obvious, on-router help is sufficient), for example:

archive
 log config
  logging enable 100
  notify syslog
  hidekeys

After you've enabled configuration command logging, you can use the show archive log config all command to inspect the logging buffer. You can also display commands entered in a particular session or by a selected user.

If you've configured notify syslog, every configuration command also triggers a syslog message similar to this one:

3d03h: %PARSER-5-CFGLOG_LOGGEDCMD: User:console logged command:interface loopback 0

Note: This feature logs only the configuration commands, if you want to log all commands, use TACACS+ or Embedded Event Manager.

The Cisco IOS’s AAA architecture contains many handy features, including authorizing and logging every CLI command executed on the router. Unfortunately, the AAA command accounting only supports TACACS+ as the AAA transport protocol, making it unusable in RADIUS environments.

You can use Embedded Event Manager as a workaround. The following configuration commands will log every command executed on the router.

Cisco IOS has the ability to define command aliases - short words that substitute a whole exec-mode or configuration command. These aliases can also be used in command execution URLs. For example, if you define alias exec showdefault show ip route 0.0.0.0 0.0.0.0, you can view the status of the default route with the http://router/exec/showdefault/CR URL.

Microsoft decided a while ago to disable the ability to send username and password encoded in URL to a web server. This "security patch" also prevents you from serving files from Cisco IOS web server without explicit user login (IOS web server does not support anonymous access). However, as the Microsoft patch does not affect FTP, you can use FTP server embedded in most Cisco IOS images and download files to your web browser with the ftp://user:password@router/file URL.

To enable FTP server in Cisco IOS, use the ftp-server enable configuration command followed by the ftp-server topdir directory command which specifies the top-level FTP directory (for example, flash:). To authenticate FTP users, define local usernames with the username user password password configuration command.

To optimize the space utilizations and file transfer operations in flash: memory, Cisco IOS web server allows files to be served from tar archives stored on flash: (or any other) filesystem. The URL syntax to access a file in a tar archive is /archive/archive-name-without-tar-suffix/file-in-archive.

Cisco IOS supports the Unix tar format with the archive command. For example, to inspect the contents of the Secure Device Manager (SDM) that is present in Flash memory on most routers, use the archive tar /table flash:sdm.tar command.

You can also use the archive tar /xtract command to extract a tar file (local or external) into a directory (yet again local or external). For example, with the command archive tar /xtract flash:sdm.tar tftp://10.0.0.10 you'd extract the SDM tar archive to a TFTP server.

Note: tar extract cannot create subdirectories on a TFTP server, the directory structure has to be prepared in advance.

Another un(der)documented fact: when you access the router's home page (assuming HTTP or HTTPS server has been enabled), the router displays:

1. The home.html file if it exists in any filesystem;
2. The home.shtml file if it exists in any filesystem;
3. a default page with links to exec, SDM, QDM and TAC support

Note: even though you can access home.html file on flash: device directly, that web page cannot reference any other file in flash: as a relative link unless you specify flash: as the default path for the HTTP requests with the ip http path flash: command.

Syslog has always been considered an undependable means of reporting network problems by serious network administrators as it runs over unreliable UDP transport. Sometime in the twilight zone between IOS releases 12.3T and 12.4, Cisco IOS got the capability to transport syslog messages over TCP with the logging host ip-address transport tcp port configuration command (the command is documented in 12.4 manuals but missing in 12.3T manuals).

Note: IOS implements standard syslog stream over TCP, not the more complex RFC 3195.

To support syslog over TCP, you also need TCP-capable syslog server. In Unix environments, you can use syslog-ng, on Windows, Kiwi syslog daemon is a perfect choice.

Note: to enable syslog over TCP in Kiwi Syslog Daemon, go to File/Setup/Inputs/TCP, click Listen for TCP Syslog messages and enter the desired TCP port number.