Changing the theme to require less energy to display (in theory, on CRT:s anyway ).

Set a password

The first thing to do is changing the password for the default user “admin”. When you are logged in, you can do this two ways (at least), either by setting it directly:

[admin@MikroTik] > user set admin password=somegoodpassword

Or by using the “password” utility to set the password interactively:

[admin@MikroTik] > password
old password: ********
new password: ********
retype new password: ********

Basic wireless security

The default configuration is a completely open wireless network, with the ESSID “MikroTik”:

[admin@MikroTik] > interface wireless print
Flags: X - disabled, R - running
 0    name="wlan1" mtu=1500 mac-address=00:0C:42:FC:B9:2B arp=enabled interface-type=Atheros 11N mode=ap-bridge
      ssid="MikroTik" frequency=2412 band=2ghz-b/g/n channel-width=20/40mhz-ht-above scan-list=default
      wireless-protocol=any antenna-mode=ant-a wds-mode=disabled wds-default-bridge=none wds-ignore-ssid=no
      bridge-mode=enabled default-authentication=yes default-forwarding=yes default-ap-tx-limit=0
      default-client-tx-limit=0 hide-ssid=no security-profile=default compression=no

The first thing we need to do is to configure some wireless security. I choose WPA2-PSK (pre-shared key), because it is easy and simple to setup, and also simple and quick to configure on clients. Here is how you configure it, first take a look at the current wireless security profile, notice that there is a “0″ first, this number is used later when configuring the profile, to identify it:

[admin@MikroTik] > interface wireless security-profiles print
0 name="default" mode=none authentication-types="" unicast-ciphers="" group-ciphers="" wpa-pre-shared-key=""
   wpa2-pre-shared-key="" supplicant-identity="MikroTik" eap-methods=passthrough tls-mode=no-certificates
   tls-certificate=none static-algo-0=none static-key-0="" static-algo-1=none static-key-1="" static-algo-2=none
   static-key-2="" static-algo-3=none static-key-3="" static-transmit-key=key-0 static-sta-private-algo=none
   static-sta-private-key="" radius-mac-authentication=no radius-mac-accounting=no radius-eap-accounting=no
   interim-update=0s radius-mac-format=XX:XX:XX:XX:XX:XX radius-mac-mode=as-username radius-mac-caching=disabled
   group-key-update=5m management-protection=disabled management-protection-key=""

You can set each parameter separately, or all that we want to change at once, in one line. Let’s do it by setting them all at once:

[admin@MikroTik] > interface wireless security-profiles set mode=dynamic-keys authentication-types=wpa2-psk unicast-ciphers=aes-ccm group-ciphers=aes-ccm  wpa2-pre-shared-key=longrandomlycreatedkey numbers=0

Notice the “numbers=0″ at the end, that means that we are setting the parameters for the number “0″, the first and default wireless security-profile. The “wpa2-pre-shared-key” value “longrandomlycreatedkey” is of course only an example. Create/come up with a long, strong and secure key, and keep it locked in if you write it down on paper, or in a file on a removable storage medium.

Let’s check the configuration we applied:

[admin@MikroTik] > interface wireless security-profiles print
 0 name="default" mode=dynamic-keys authentication-types=wpa2-psk unicast-ciphers=aes-ccm group-ciphers=aes-ccm
   wpa-pre-shared-key="" wpa2-pre-shared-key="longrandomlycreatedkey" supplicant-identity="MikroTik"
   eap-methods=passthrough tls-mode=no-certificates tls-certificate=none static-algo-0=none static-key-0=""
   static-algo-1=none static-key-1="" static-algo-2=none static-key-2="" static-algo-3=none static-key-3=""
   static-transmit-key=key-0 static-sta-private-algo=none static-sta-private-key="" radius-mac-authentication=no
   radius-mac-accounting=no radius-eap-accounting=no interim-update=0s radius-mac-format=XX:XX:XX:XX:XX:XX
   radius-mac-mode=as-username radius-mac-caching=disabled group-key-update=5m management-protection=disabled
   management-protection-key=""

The Security Profiles properties are documented further in the manual.

Disable unnecessary services

There are some services started and running by default:

[admin@MikroTik] > ip service print detail
Flags: X - disabled, I - invalid
 0   name="telnet" port=23 

 1   name="ftp" port=21 

 2   name="www" port=80 

 3   name="ssh" port=22 

 4 X name="www-ssl" port=443 certificate=none 

 5 X name="api" port=8728 

 6   name="winbox" port=8291

SSH is enabled by default, and SFTP works nicely, so we do not need to have telnetd or the ftp-server running, let’s disable them.
Disable the telnet server:

[admin@MikroTik] > ip service disable telnet

Disable the ftp-server:

[admin@MikroTik] > ip service disable ftp

We are also not going to use the Winbox utility, so we disable that service:

[admin@MikroTik] > ip service disable winbox

If you were paying attention and used TAB as you should, you have noticed that the CLI let’s you do as many things as you like on one line, if you separate the commands with semicolon, “;”. The above could have been acomplished with a line like:

[admin@MikroTik] > ip service disable telnet ; ip service disable ftp ; ip service disable winbox

If you remember from the previous post, there is also a bandwidth testing server of some kind running on port 2000, not listed in the IP services, let’s disable that too:

[admin@MikroTik] > tool bandwidth-server set enabled=no

Test and confirm

Check which services are running now:

[admin@MikroTik] > ip service print detail
Flags: X - disabled, I - invalid
 0 X name="telnet" port=23 

 1 X name="ftp" port=21 

 2   name="www" port=80 

 3   name="ssh" port=22 

 4 X name="www-ssl" port=443 certificate=none 

 5 X name="api" port=8728 

 6 X name="winbox" port=8291

and:

[admin@MikroTik] > tool bandwidth-server print
                  enabled: no
             authenticate: yes
  allocate-udp-ports-from: 2000
             max-sessions: 100

Alright, that looks like we want it. Let’s confirm:

root@messtent:~# nmap -A -p0-65535 192.168.88.1 

Starting Nmap 5.00 ( http://nmap.org ) at 2012-03-26 05:42 CEST
Interesting ports on 192.168.88.1:
Not shown: 65533 closed ports
PORT   STATE SERVICE VERSION
22/tcp open  ssh     (protocol 2.0)
|_ ssh-hostkey: 1024 [...] (DSA)
53/tcp open  domain?
80/tcp open  http?
|  robots.txt: has 1 disallowed entry
|_ /
|_ html-title: RouterOS router configuration page
[...]

Nice, the services are really stopped.

Testing wireless

root@messtent:~# iwconfig wlan0 ; ifconfig wlan0 ; wpa_cli status ; echo ; ping -f -c 10000 -s 1500 192.168.88.1
wlan0     IEEE 802.11abgn  ESSID:"MikroTik"
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:0C:42:[...]
          Bit Rate=150 Mb/s   Tx-Power=15 dBm
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=70/70  Signal level=-8 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

wlan0     Link encap:Ethernet  HWaddr 00:21:5d:[...]
          inet addr:192.168.88.252  Bcast:192.168.88.255  Mask:255.255.255.0
          inet6 addr: fe80::221:5d[...]/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7371256 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10303519 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:3847289761 (3.5 GiB)  TX bytes:11677149925 (10.8 GiB)

Selected interface 'wlan0'
bssid=00:0c:42:[...]
ssid=MikroTik
id=0
pairwise_cipher=CCMP
group_cipher=CCMP
key_mgmt=WPA2-PSK
wpa_state=COMPLETED
ip_address=192.168.88.252

PING 192.168.88.1 (192.168.88.1) 1500(1528) bytes of data.

--- 192.168.88.1 ping statistics ---
10000 packets transmitted, 10000 received, 0% packet loss, time 27908ms
rtt min/avg/max/mdev = 2.280/2.686/22.347/0.868 ms, pipe 2, ipg/ewma 2.791/2.788 ms

Our wireless security profile works, and traffic can flow, and quite well too.

Configuration backup

To export the current configuration (with all keys in cleartext):

[admin@MikroTik] > export file=secured_default

Note however, that the user and passwords are not saved with the above. They are however saved with the binary configuration backup:

[admin@MikroTik] > system backup save name=secured_default_bin

[admin@MikroTik] > file print
 # NAME                                TYPE                                                     SIZE CREATION-TIME
 0 skins                               directory                                                     jan/01/1970 00:00:53
 1 auto-before-reset.backup            backup                                                 13 178 jan/02/1970 00:00:55
 2 secured_default.rsc                 script                                                 17 695 jan/03/1970 04:43:25
 3 secured_default_bin.backup          backup                                                 21 143 jan/03/1970 04:44:06

Download the files to your computer and examine them. Keep them safe because they contain your keys and passwords.

root@messtent:~/mikrotik# sftp admin@192.168.88.1
admin@192.168.88.1's password:
Connected to 192.168.88.1.
sftp> ls
auto-before-reset.backup      secured_default.rsc           secured_default_bin.backup    skins
sftp> get *.*
Fetching /auto-before-reset.backup to auto-before-reset.backup
/auto-before-reset.backup                                                               100%   13KB  12.9KB/s   00:00
Fetching /secured_default.rsc to secured_default.rsc
/secured_default.rsc                                                                    100%   17KB  17.3KB/s   00:00
Fetching /secured_default_bin.backup to secured_default_bin.backup
/secured_default_bin.backup                                                             100%   21KB  20.7KB/s   00:00

Related articles

• Examining, configuring and playing with the MikroTik RouterBOARD RB751G-2HnD for the first time
• Securing the MikroTik RouterBOARD RB751G-2HnD (or any RouterOS device) - the bare minimum

I hope this has been informative, and I would like to thank You for reading. Feel free to comment.

The labeling on my case is “RouterBOARD 751G”.

The product page says says:

The RB751G is the wireless SOHO Gigabit AP you have been waiting for. It has five Gigabit Ethernet ports, one USB 2.0 port and a high power 30dBi/1W 802.11b/g/n wireless AP with antennas built in.

It’s also possible to connect an external MMCX antenna to replace one of the built in antennas. The device is very small and will look good in any home or office, wall mounting anchor holes are provided.

Package contains RouterBOARD 751G-2HnD in a plastic case and power adapter.

RB751G-2HnD will be available in United States through our Distributor network when FCC certification will be ready, hopefully by the end of March.

Specifications

Ethernet throughput

Powering up and connecting

Alright, we are ready to power it up. The Quick Setup Guide says:

 

Powering

The device accepts powering from the power jack or from the first Ethernet port (Passive PoE):

• DC power jack (5.5mm outside and 2mm inside diameter, female, pin positive plug) accepts 8-30V DC
• The first Ethernet port accepts passive Power over Ethernet accepts 8-30V DC

Under maximum load, the power consumption of this device is 7W

I currently do not have a PoE-switch or any power injector to give the RouterBOARD power on its first ethernet port, which is the 751G’s incoming PoE-port (the so-called “WAN-port”, the uplink port).
(Update: As “P” kindly points out in his comment below, a PoE-switch would not have helped me much, since the RB751G-2HnD does not support 802.3af, only DC-power injected directly on the right pair.)
Instead I connect the DC power adapter to a power outlet, then to the device, and we have blinkenlights!
After that I connect a straight CAT 5 cable to my laptop, and to port 4 (the fifth, rightmost RJ45-port on the device).

My laptop’s eth0 (first Ethernet port) is configured as:

allow-hotplug eth0
iface eth0 inet dhcp

So, I quite immediately get an IP address from the RouterBOARD’s DHCP server:

eth0      Link encap:Ethernet  HWaddr [...]
          inet addr:192.168.88.254  Bcast:192.168.88.255  Mask:255.255.255.0
[...]

The Quick Setup Guide says:

Connecting

1. Connect your Internet cable to port 1, and LAN computers to ports 2-5
2. Set LAN computer IP configuration to automatic (DHCP)
3. Default IP address from LAN/WLAN is 192.168.88.1, connect with SSH, Telnet or Winbox tool for configuration. The username is admin and there is no password
4. Wireless AP mode is enabled by default, you can connect to the SSID “MikroTik”. Log into your router and configure a WPA wireless password to secure your network

SSH and default configuration

So I connected to it with ssh, without entering a password, and was presented with:

ssh admin@192.168.88.1

  MMM MMMM MMM  III  KKK  KKK  RRRRRR     OOOOOO      TTT     III  KKK  KKK
  MMM  MM  MMM  III  KKKKK     RRR  RRR  OOO  OOO     TTT     III  KKKKK
  MMM      MMM  III  KKK KKK   RRRRRR    OOO  OOO     TTT     III  KKK KKK
  MMM      MMM  III  KKK  KKK  RRR  RRR   OOOOOO      TTT     III  KKK  KKK

  MikroTik RouterOS 5.6 (c) 1999-2011       http://www.mikrotik.com/

The following default configuration has been installed on your router:
-------------------------------------------------------------------------------
ether1 is renamed to ether1-gateway
DHCP client and masquerade is set on ether1-gateway
ether2 is renamed to ether2-master-local and configured as switch master port for ether3-ether5
ether2-master-local and wlan1 are bridged
wireless is set as access point in 2412MHz using both chains and extension channel enabled.
IP address 192.168.88.1/24 and DHCP server is set on bridge interface
   P servers address pool is 192.168.88.10-192.168.88.254

'/system default-configuration print' command.
To remove this default configuration type "r" or hit any other key to continue.
If you are connected using the above IP and you remove it, you will be disconnected.

Confirming configuration

As logical minds will conclude from the output, I hit the any key, and continued. One can also observe that the DHCP pool is seemingly assigning addresses to hosts downwards from the pool’s max value, which is a good as any design decision. (Unless it is random, and we were extremely lucky this time to be assigned 192.168.88.254.)
After that I disconnected, and connected again, and was then presented with:

  MMM      MMM       KKK                          TTTTTTTTTTT      KKK
  MMMM    MMMM       KKK                          TTTTTTTTTTT      KKK
  MMM MMMM MMM  III  KKK  KKK  RRRRRR     OOOOOO      TTT     III  KKK  KKK
  MMM  MM  MMM  III  KKKKK     RRR  RRR  OOO  OOO     TTT     III  KKKKK
  MMM      MMM  III  KKK KKK   RRRRRR    OOO  OOO     TTT     III  KKK KKK
  MMM      MMM  III  KKK  KKK  RRR  RRR   OOOOOO      TTT     III  KKK  KKK

  MikroTik RouterOS 5.6 (c) 1999-2011       http://www.mikrotik.com/

[admin@MikroTik] >

A press on TAB reveals the available RouterOS commands:

certificate  interface  metarouter  ppp     routing        store   user   export  password  redo
driver       ip         mpls        queue   snmp           system  beep   import  ping      setup
file         log        port        radius  special-login  tool    blink  led     quit      undo
[admin@MikroTik] >

After a few seconds, TAB-completions and “?” I found:

[admin@MikroTik] > system routerboard print
       routerboard: yes
             model: 751G-2HnD
     serial-number: [...]
  current-firmware: 2.37
  upgrade-firmware: 2.36

The full list of available commands in the root of the command tree is listed with a question mark, “?”, (the first or second button one presses in a terminal when dealing with network equipment, or any system really, if one has worked with any common brand/model/os):

beep --
blink --
certificate -- Certificate management
delay -- does nothing for a while
do -- executes command
driver -- Driver management
environment -- list of all variables
error -- make error value
execute -- run script as separate console job
file -- Local router file storage.
find -- Find items by value
for -- executes command for a range of integer values
foreach -- executes command for every element in a list
global -- set value global variable
if -- executes command if condition is true
import --
interface --
ip -- IP options
led --
len -- return number of elements in value
local -- set value of local variable
log -- System logs
metarouter --
mpls --
nothing -- do nothing and return nothing
parse -- build command from text
password -- Change password
pick -- return range of string characters or array values
ping -- Send ICMP Echo packets
port -- Serial ports
ppp -- Point to Point Protocol
put -- prints argument on the screen
queue -- Bandwidth management
quit -- Quit console
radius -- Radius client settings
redo -- Redo previously undone action
resolve -- perform a dns lookup of domain name
routing --
set -- Change item properties
setup -- Do basic setup of system
snmp -- SNMP settings
special-login -- Special login users
store --
system -- System information and utilities
terminal -- commands related to terminal handling
time -- returns time taken by command to execute
toarray -- convert argument to array value
tobool -- convert argument to truth value
toid -- convert argument to internal number value
toip -- convert argument to IP address value
toip6 -- convert argument to IPv6 address value
tonum -- convert argument to integer number value
tool -- Diagnostics tools
tostr -- convert argument to string value
totime -- convert argument to time interval value
typeof -- return type of value
undo -- Undo previous action
user -- User management
while -- executes command while condition is true
export -- Print or save an export script that can be used to restore configuration

The first thing one just has to try is of course “blink”:

[admin@MikroTik] > blink duration=1 ;

And it blinks its ACT (Activity) LED! I’m already starting to love this little thing. I guess it does not have any tiny speaker connected, because the “beep” command doesn’t produce any sound, though the command works. (The semicolon above is not necessary, but it is added if TAB-completing. That brings me to another observation, the CLI-interface is very easily understood, beautiful, intuitive, helpful and just.. nice.
Let’s see what IP services it’s running by default (the addition of “detail” doesn’t give more detailed output in this case, but it formats the output better for pasting here, try it without “detail” yourself to see what I mean):

[admin@MikroTik] > ip service print detail
Flags: X - disabled, I - invalid
 0   name="telnet" port=23 

 1   name="ftp" port=21 

 2   name="www" port=80 

 3   name="ssh" port=22 

 4 X name="www-ssl" port=443 certificate=none 

 5 X name="api" port=8728 

 6   name="winbox" port=8291

Let’s see and confirm if that is the truth, and what the services say:

PORT     STATE SERVICE
21/tcp   open  ftp
22/tcp   open  ssh
23/tcp   open  telnet
53/tcp   open  domain
80/tcp   open  http
2000/tcp open  callbook
8291/tcp open  unknown

PORT     STATE SERVICE   VERSION
21/tcp   open  ftp       MikroTik router ftpd 5.6
22/tcp   open  ssh       (protocol 2.0)
|_ ssh-hostkey: 1024 [...] (DSA)
23/tcp   open  telnet    Linux telnetd
53/tcp   open  domain?
80/tcp   open  http?
|  robots.txt: has 1 disallowed entry
|_ /
|_ html-title: RouterOS router configuration page
2000/tcp open  callbook?

So, it also runs a DNS server/forwarder, and something on port 2000, by default, which doesn’t show when looking at the services configuration of the device.

[admin@MikroTik] > tool bandwidth-server print
                  enabled: yes
             authenticate: yes
  allocate-udp-ports-from: 2000
             max-sessions: 100

As you see, it runs some form of bandwidth testing server on port 2000. I have to look into that more another time. It’s documented in their wiki. Perhaps/probably the server and client is proprietary, but we’ll have to investigate further later like I said.

I also noticed that critical log messages are printed to the console (my ssh session). The following happened when I scanned it: (since it has not yet had Internet access it has not had the opportunity to set its clock using NTP yet, if it does by default, and I have not yet set it, if you are wondering)

jan/02/1970 03:54:36 system,error,critical login failure for user anonymous from 192.168.88.254 via ftp

Web interface

The next thing to check is the web-interface, which is running by default. It looks like this:

When clicking on the WebFig-icon, we are given a login prompt, we log in with the default username “admin”, and no password, and we are presented with:

The configuration hierarchy in the WebFig interface is the same as in the command line interface, and it seems logical, straightforward and clean, as it should be.

Wireless

I also connected to it over wireless, using the following /etc/network/interfaces configuration:

# MikroTik
allow-hotplug wlan0
iface wlan0 inet dhcp
    wireless-essid MikroTik

On my laptop:

wlan0     IEEE 802.11abgn  ESSID:"MikroTik"
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:0C:42:[..]
          Bit Rate=150 Mb/s   Tx-Power=15 dBm
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=70/70  Signal level=-8 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

And on the RB751G:

[admin@MikroTik] > interface wireless registration-table print
 # INTERFACE                          RADIO-NAME       MAC-ADDRESS       AP  SIGNAL-STRENGTH TX-RATE UPTIME
 0 wlan1                                               00:21:5D:[..]     no  -34dBm@HT40-7   36.0... 3m48s

Conclusion

I’m really impressed by the MikroTik RouterBOARD RB751G-2HnD so far, by just looking at it quickly like this. I will lab/play more with it and test out its functions in later articles.

Related articles

• Examining, configuring and playing with the MikroTik RouterBOARD RB751G-2HnD for the first time
• Securing the MikroTik RouterBOARD RB751G-2HnD (or any RouterOS device) - the bare minimum

I hope this has been informative, and I would like to thank You for reading. Feel free to comment.

READY
RUN

HELLO BA 5A

HELLO, MY NAME IS PETEY P. EIGHT.

WHAT’S YOUR NAME ?BEARDY

HI THERE BEARDY. ARE YOU ENJOYING YOURSELF HERE
IN THIS WONDERFUL PLACE?YES

OH, I’M GLAD TO HEAR THAT BEARDY

SAY, BEARDY, I CAN SOLVE ALL KINDS OF PROBLEMS
EXCEPT THOSE DEALING WITH GREECE. WHAT KIND OF
PROBLEMS DO YOU HAVE (ANSWER SEX, HEALTH, MONEY,
OR JOB)?

Not even a DEC PDP-8 (simulated in SIMH) running OS/8 and a BASIC program, HELLO.BA, can help with Greece!

Guess if I dropped my jaw in surprise and amusement when I read that, when playing around with a simulated historic computer just now. If not even that can help to solve the problems of/with Greece, I guess they’re doomed!

On another note, SIMH is a great thing, the DEC PDP-8 minicomputer (from 1965) seems to have been a nice machine in its days, and OS/8 quite a decent OS for its time and environment. Expect another post on SIMH and simulating/emulating old computers shortly.

Jobs that should be run by cron are specified in crontab (cron table) files. A crontab is a configuration file that specifies commands (shell commands, including programs, scripts, or pipelines thereof) to be run, and when they should be executed.

Each line in a crontab file represents a “job”, and is composed of a CRON expression (specifying the time) followed by the command or commands to be executed. There are two different crontab files, the ones installed by system software, and editable only by root (but in most cases best left alone), and crontab files written by and belonging to users (including root). The authorization control to cron, who will be allowed to have a crontab or not, are done with the files /etc/cron.allow and /etc/cron.deny.

The manpages of cron and the crontab format are nice. “crontab” is both the name of the program installing, listing and editing user’s crontabs, and the file format manpage, so do read them:

man cron
man 1 crontab
man 5 crontab

The page in section 5, about the format is most interesting. However I prefer to keep a short reference in my user’s crontab file itself for quick reference, feel free to grab it:

# mycrontab.txt
# beardy
# My example crontab, kept in ~/

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Send the mail to another address than the local user
##MAILTO=foo@foo.bar

##############################################################################
#
# The following example should run "true" every day of every month, at half
# past eight, every day of the week.
#
# Example:
#
# 30 8  * * *   true
# |  |  | | |    |
# |  |  | | |    +--- command, or script, to run
# |  |  | | +-------- day of week, 0-7 or mon, Tue, FRI
# |  |  | +---------- month, 1-12, or names, jan, Mar, AUG (case doesn't matter)
# |  |  +------------ date, 1-31
# |  +--------------- hour, 0-23
# +------------------ minute, 0-59
#
# see "man 5 crontab"
#
#     Instead of the first five fields, one of eight special strings may
#     appear:
#
#           string          meaning
#           ------          -------
#           @reboot         Run once, at startup.
#           @yearly         Run once a year, "0 0 1 1 *".
#           @annually       (same as @yearly)
#           @monthly        Run once a month, "0 0 1 * *".
#           @weekly         Run once a week, "0 0 * * 0".
#           @daily          Run once a day, "0 0 * * *".
#           @midnight       (same as @daily)
#           @hourly         Run once an hour, "0 * * * *".
#
##############################################################################

# Run beep every Christmas Eve, at 14:40 (20 min before Kalle Anka)
#40 14  24 12 * beep -f 1000 -r 5 -l 150 -D 250
# next job goes after this line
40 14   24 12 * echo "God Jul!"

To install a new crontab, the crontab(1) program is used:

crontab mycrontab.txt

To later list it, and edit it (with the editor configured with the $EDITOR environment variable usually):

crontab -l
crontab -e

Read more about cron and crontab:

cron(8)
crontab(1)
crontab(5)
Time – An important Subject with any OS

(Update: I noticed that Opera has apparently had a menu entry in its package before, but has now removed it. It’s explained in this post, but I still think that was a bad choice.)

To override, or in this case add menufiles in Debian, one should put the files in /etc/menu. Put the following in /etc/menu/opera:

?package(opera):needs="x11" section="Applications/Network/Web Browsing" \
  title="Opera" command="/usr/bin/opera" hints="Web browsers" \
  icon="/usr/share/icons/hicolor/32x32/apps/opera-browser.xpm"

And the following in /etc/menu/skype:

?package(skype):needs="X11" section="Applications/Network/Communication" \
        title="Skype" \
        longtitle="Skype" \
        icon="" \
        command="skype"

Then run ‘update-menus‘ after you have added the above files to update the menu system, and have Opera and Skype available in your window manager’s menus.

From high-tech trysts to selling black-market software, computers users are talking.

Guests: Ezra Shapiro, Byte Magazine; Rory O’Connor, InforWorld; Matthew McClure, The Well; Donald Ingrim, Alameda County DA; George Morrow, Morrow Computing

Products/Demos: CompuServe, Byte BBS, The Well

Let’s hear your thoughts and comments after watching the video, enjoy.

Related posts:

• IBM Clones, The Computer Chronicles
• If a PDP-8 minicomputer can't help with Greece, who can?
• How computer and operating system introduction courses should be done
• UNIX, The Computer Chronicles
• Modems & Bulletin Boards, The Computer Chronicles

Advanced Permalinks dashboard screenshot

Yesterday I decided to change the permalinks structure of this site. I wondered if WordPress had redirection built into to the core, but it seems it does not yet. But there are many plugins, like always, providing the needed functionlity. At first I looked at one called Redirection, but it was not really what I was after. If seems to do most things one could want regarding redirects and 404 logging, but I only wanted to simply redirect my old “YYYY/MM/DD/postname” structure to “/postname”. I then tried another plugin called Advanced Permalinks, which does exactly what I wanted. After installing it, its options/functionality is found under Settings->Permalinks->Migration in the WordPress administration dashboard.

This allows you to move from one permalink structure to another one, and have the old structure be forwarded to the new, for each post. I used the “/%year%/%monthnum%/%day%/%postname%/” structure before, but I switched to the “/%postname%/” structure. Now, with the Advanced Permalinks plugin my possible old links in to my articles are forwarded properly.

The second plugin I installed and tried yesterday was Optimize DB, a simple plugin that just does what the name says, optimizes the MySQL database with one click. Seems to do its work well too. For my little site it wasn’t that much to optimize, but a few kilobytes atleast.

The third plugin I installed, and which you can see the effects of in this post, is Lightbox Plus, which handles the viewing of images fullsize in an overlay frame using javascript, instead of opening the image directly. Click on the image in this post and see.

Are you using any of these plugins and have anything to add? leave a comment.