AdminSky.org

This file configures the NTP daemon. Usable public NTP servers in Finland are fi.pool.ntp.org, elsewhere in Europe europe.pool.ntp.org. You should always place two to four NTP servers to ntp.conf file. Due to the nature of *.pool.ntp.org, you should just have the same line four times in the configuration file. Check www.pool.ntp.org for a public NTP server close to you. Remember to change the service to autostart at runlevel 3.

This directory contains the K(ill) and S(tart) scripts for the default runlevel 3. The services starting with “S” are started on this runlevel, and the services Starting with “K” are killed, i.e. not started..
The number after the K or S determines the order in which the scripts will run.
S scripts will run in ascending order
K scripts will run in descending order

A text file that can be checked to see what swap the service console is using. The output contains a priority which shows which swap device will be used first before the other(s). Useful to determine if swap space is getting used and if there is more than 1 swap. Remember this is vmnix (service console) swap, not VMkernel. The VMkernel swap is in one or more files on a VMFS volume (hence the strong recommendation that even when using a SAN, a vmfs volume is created on direct attached storage to allow local swap).

This file configures what things are logged and where. Some examples are given below:

*.crit     /dev/tty12

This example logs all log items at level “crit” (critical) or higher to the virtual terminal at tty12. You can see this log by pressing [Alt]-[F12] on the console.

*.=err     /dev/tty11

This example logs all log items at exactly level “err” (error) to the virtual terminal at tty11. You can see this log by pressing [Alt]-[F11] on the console.

*.=warning     /dev/tty10

This example logs all log items at exactly level “warning” to the virtual terminal at tty10. You can see this log by pressing [Alt]-[F10] on the console.

*.*     10.30.10.52

This example forwards everything (all syslog entries) un-encrypted to another (central) syslog server. Pay attention to that server’s security.

This directory contains all the SSH daemon configuration files, public and public keys. The defaults are both secure and flexible and rarely need any changing. The only exception is a change to /etc/ssh/sshd_config file if you want to restrict logins for root user.
Quick way to restart the ssh daemon. Use full path to do this.
/etc/init.d/sshd restart
/etc/ssh/ssh_config
Text file with the configuration of SSH client.
/etc/ssh/sshd_config
Text file with the configuration file for SSH daemon. An important setting in this file is PermitRootLogin=Yes/No. You can quickly check this with a grep on the file.
grep permit /etc/ssh/sshd_config
~/.ssh/known_hosts

Allow or deny SSH for specified users:
add the following lines to the sshd_config file

AllowUsers user1 user2 user3 ….

Deny Users user1 user2 user3 ….

A text file that stores the RSA keys for known hosts. If we rebuild a host and then reconnect to it over SSH we may be prevented if the known_hosts file has cached the old key. I think SCP (secure copy) uses RSA keys as well as SSH sessions. Note this file is maintained on a per-user basis.