YobiWiki - User contributions [en]

Munin

2006-11-29T23:38:24Z

85.234.199.11: /* sensors_ plugin */

Munin is a nice Monitoring framework

==Sites==
* http://munin.projects.linpro.no/
* http://www.debian-administration.org/articles/229
* http://www.debianhelp.co.uk/munin.htm

==Installation==
===On the collector===
apt-get install munin libdate-manip-perl
Configure /etc/munin/munin.conf to add nodes to collect
===On each node===
apt-get install munin-node libnet-snmp-perl libio-socket-ssl-perl libcrypt-des-perl libdigest-hmac-perl libio-socket-inet6-perl libwww-perl libnet-irc-perl smartmontools ethtool
Maybe you will have to relax the firewall when installing munin otherwise install will stall during plugin detection if loopback connections to port 3128 are dropped.
 Bind the monitor only to the wanted IP in /etc/munin/munin-node.conf and tell which server can get the info:
host <my_ip>
allow ^<regex IP of the collector>$ (see examples)
Select plugins from /usr/share/munin/plugins by adding a symlink in /etc/munin/plugins
 To know if a plugin could work, try it with argument "autoconf", if it says yes then it is usable otherwise look inside the plugin code (perl) for hints.
 Some plugins require some options to be configured, do that in /etc/munin/plugin-conf.d/munin-node

====apache_* plugin====
Activate apache2 extended status (cf http://www.debian-administration.org/articles/161):
 Install mod_info:
a2enmod info
Activate in /etc/apache2/apache2.conf the section:
<Location /server-status> etc
and add just above this section the following line:
ExtendedStatus On

/etc/init.d/apache2 force-reload
Add to /etc/munin/plugin-conf.d/munin-node:
<pre>
[apache_*]
env.lrrd_url "http://<my_ip>:%d/server-status?auto"
</pre>
====ip_ plugin====
Add to /etc/munin/plugin-conf.d/munin-node (normally it is already done in the last versions):
[ip_*]
user root
Add iptables dummy rules to collect stats on a particular IP:
iptables -A INPUT -d <ip>;iptables -A OUTPUT -s <ip>
Install the plugin for this ip:
ln -s /usr/share/munin/plugins/ip_ /etc/munin/plugins/ip_<ip>

====sensors_ plugin====
Usually you create symlinks calles sensors_fan, sensors_volt and sensors_temp.

I had many troubles after a kernel upgrade:
 Now the output of "sensors" features a "phantom" chip w83627hf-i2c-0-28 with no valid values, aside the 2 others, w83782d-i2c-0-29 and w83627hf-isa-0290.
 One more or less correct way would be to e.g. add an entry at the end of /etc/sensors.conf with
chip "w83627hf-i2c-*"
ignore in0
...
But sth is really wrong no way to get a section only considered by the -isa- and the other by -i2c-, whatever I tried both sections were submitted to the same filtering rules :-(

Last resort was to change the output of sensors when called by munin:
 In /etc/munin/plugin-conf.d/munin-node:
[sensors_*]
env.sensors sensors|sed '1,+14d'
But the entry order was not the same as before, the sections have to be inverted and some new values must be postponed to the end to keep the uniformity in the history values.
 So it becomes:
[sensors_*]
env.sensors sensors|awk 'b==1{p=p"\n"$0};b==2&&/^in/{o=o"\n"$0;next};b==2;/^$/{b+=1};END{print p o}'

====Other plugins====
More info on plugins incl. how to write yours: http://munin.projects.linpro.no/wiki/HowToWritePlugins

Munin

2006-11-29T21:54:25Z

85.234.199.11: /* sensors_ plugin */

Munin is a nice Monitoring framework

==Sites==
* http://munin.projects.linpro.no/
* http://www.debian-administration.org/articles/229
* http://www.debianhelp.co.uk/munin.htm

==Installation==
===On the collector===
apt-get install munin libdate-manip-perl
Configure /etc/munin/munin.conf to add nodes to collect
===On each node===
apt-get install munin-node libnet-snmp-perl libio-socket-ssl-perl libcrypt-des-perl libdigest-hmac-perl libio-socket-inet6-perl libwww-perl libnet-irc-perl smartmontools ethtool
Maybe you will have to relax the firewall when installing munin otherwise install will stall during plugin detection if loopback connections to port 3128 are dropped.
 Bind the monitor only to the wanted IP in /etc/munin/munin-node.conf and tell which server can get the info:
host <my_ip>
allow ^<regex IP of the collector>$ (see examples)
Select plugins from /usr/share/munin/plugins by adding a symlink in /etc/munin/plugins
 To know if a plugin could work, try it with argument "autoconf", if it says yes then it is usable otherwise look inside the plugin code (perl) for hints.
 Some plugins require some options to be configured, do that in /etc/munin/plugin-conf.d/munin-node

====apache_* plugin====
Activate apache2 extended status (cf http://www.debian-administration.org/articles/161):
 Install mod_info:
a2enmod info
Activate in /etc/apache2/apache2.conf the section:
<Location /server-status> etc
and add just above this section the following line:
ExtendedStatus On

/etc/init.d/apache2 force-reload
Add to /etc/munin/plugin-conf.d/munin-node:
<pre>
[apache_*]
env.lrrd_url "http://<my_ip>:%d/server-status?auto"
</pre>
====ip_ plugin====
Add to /etc/munin/plugin-conf.d/munin-node (normally it is already done in the last versions):
[ip_*]
user root
Add iptables dummy rules to collect stats on a particular IP:
iptables -A INPUT -d <ip>;iptables -A OUTPUT -s <ip>
Install the plugin for this ip:
ln -s /usr/share/munin/plugins/ip_ /etc/munin/plugins/ip_<ip>

====sensors_ plugin====
Usually you create symlinks calles sensors_fan, sensors_volt and sensors_temp.

I had many troubles after a kernel upgrade:
 Now the output of "sensors" features a "phantom" chip w83627hf-i2c-0-28 with no valid values, aside the 2 others, w83782d-i2c-0-29 and w83627hf-isa-0290.
 One more or less correct way would be to e.g. add an entry at the end of /etc/sensors.conf with
chip "w83627hf-i2c-*"
ignore in0
...
But sth is really wrong no way to get a section only considered by the -isa- and the other by -i2c-, whatever I tried both sections were submitted to the same filtering rules :-(

Last resort was to change the output of sensors when called by munin:
 In /etc/munin/plugin-conf.d/munin-node:
[sensors_]
env.sensors sensors|sed '1,+14d'

====Other plugins====
More info on plugins incl. how to write yours: http://munin.projects.linpro.no/wiki/HowToWritePlugins

Munin

2006-11-29T21:47:31Z

85.234.199.11: /* Other plugins */

Munin is a nice Monitoring framework

==Sites==
* http://munin.projects.linpro.no/
* http://www.debian-administration.org/articles/229
* http://www.debianhelp.co.uk/munin.htm

==Installation==
===On the collector===
apt-get install munin libdate-manip-perl
Configure /etc/munin/munin.conf to add nodes to collect
===On each node===
apt-get install munin-node libnet-snmp-perl libio-socket-ssl-perl libcrypt-des-perl libdigest-hmac-perl libio-socket-inet6-perl libwww-perl libnet-irc-perl smartmontools ethtool
Maybe you will have to relax the firewall when installing munin otherwise install will stall during plugin detection if loopback connections to port 3128 are dropped.
 Bind the monitor only to the wanted IP in /etc/munin/munin-node.conf and tell which server can get the info:
host <my_ip>
allow ^<regex IP of the collector>$ (see examples)
Select plugins from /usr/share/munin/plugins by adding a symlink in /etc/munin/plugins
 To know if a plugin could work, try it with argument "autoconf", if it says yes then it is usable otherwise look inside the plugin code (perl) for hints.
 Some plugins require some options to be configured, do that in /etc/munin/plugin-conf.d/munin-node

====apache_* plugin====
Activate apache2 extended status (cf http://www.debian-administration.org/articles/161):
 Install mod_info:
a2enmod info
Activate in /etc/apache2/apache2.conf the section:
<Location /server-status> etc
and add just above this section the following line:
ExtendedStatus On

/etc/init.d/apache2 force-reload
Add to /etc/munin/plugin-conf.d/munin-node:
<pre>
[apache_*]
env.lrrd_url "http://<my_ip>:%d/server-status?auto"
</pre>
====ip_ plugin====
Add to /etc/munin/plugin-conf.d/munin-node (normally it is already done in the last versions):
[ip_*]
user root
Add iptables dummy rules to collect stats on a particular IP:
iptables -A INPUT -d <ip>;iptables -A OUTPUT -s <ip>
Install the plugin for this ip:
ln -s /usr/share/munin/plugins/ip_ /etc/munin/plugins/ip_<ip>

====sensors_ plugin====
Usually you create symlinks calles sensors_fan, sensors_volt and sensors_temp.

I had many troubles after a kernel upgrade:
 Now the output of "sensors" features a "phantom" chip w83627hf-i2c-0-28 with no valid values, aside the 2 others, w83782d-i2c-0-29 and w83627hf-isa-0290.
 One more or less correct way would be to e.g. add an entry at the end of /etc/sensors.conf with
chip "w83627hf-i2c-*"
ignore in0
...
But sth is really wrong no way to get a section only considered by the -isa- and the other by -i2c-, whatever I tried both sections were submitted to the same filtering rules :-(

Last resort was to change the output of sensors when called by munin:
 In /etc/munin/plugin-conf.d/munin-node:
[sensors_]
env.sensors=sensors|sed '1,+14d'

====Other plugins====
More info on plugins incl. how to write yours: http://munin.projects.linpro.no/wiki/HowToWritePlugins

Munin

2006-11-29T21:40:07Z

85.234.199.11: /* ip_ plugin */

Munin is a nice Monitoring framework

==Sites==
* http://munin.projects.linpro.no/
* http://www.debian-administration.org/articles/229
* http://www.debianhelp.co.uk/munin.htm

==Installation==
===On the collector===
apt-get install munin libdate-manip-perl
Configure /etc/munin/munin.conf to add nodes to collect
===On each node===
apt-get install munin-node libnet-snmp-perl libio-socket-ssl-perl libcrypt-des-perl libdigest-hmac-perl libio-socket-inet6-perl libwww-perl libnet-irc-perl smartmontools ethtool
Maybe you will have to relax the firewall when installing munin otherwise install will stall during plugin detection if loopback connections to port 3128 are dropped.
 Bind the monitor only to the wanted IP in /etc/munin/munin-node.conf and tell which server can get the info:
host <my_ip>
allow ^<regex IP of the collector>$ (see examples)
Select plugins from /usr/share/munin/plugins by adding a symlink in /etc/munin/plugins
 To know if a plugin could work, try it with argument "autoconf", if it says yes then it is usable otherwise look inside the plugin code (perl) for hints.
 Some plugins require some options to be configured, do that in /etc/munin/plugin-conf.d/munin-node

====apache_* plugin====
Activate apache2 extended status (cf http://www.debian-administration.org/articles/161):
 Install mod_info:
a2enmod info
Activate in /etc/apache2/apache2.conf the section:
<Location /server-status> etc
and add just above this section the following line:
ExtendedStatus On

/etc/init.d/apache2 force-reload
Add to /etc/munin/plugin-conf.d/munin-node:
<pre>
[apache_*]
env.lrrd_url "http://<my_ip>:%d/server-status?auto"
</pre>
====ip_ plugin====
Add to /etc/munin/plugin-conf.d/munin-node (normally it is already done in the last versions):
[ip_*]
user root
Add iptables dummy rules to collect stats on a particular IP:
iptables -A INPUT -d <ip>;iptables -A OUTPUT -s <ip>
Install the plugin for this ip:
ln -s /usr/share/munin/plugins/ip_ /etc/munin/plugins/ip_<ip>

====sensors_ plugin====
Usually you create symlinks calles sensors_fan, sensors_volt and sensors_temp.

I had many troubles after a kernel upgrade:
 Now the output of "sensors" features a "phantom" chip w83627hf-i2c-0-28 with no valid values, aside the 2 others, w83782d-i2c-0-29 and w83627hf-isa-0290.
 One more or less correct way would be to e.g. add an entry at the end of /etc/sensors.conf with
chip "w83627hf-i2c-*"
ignore in0
...
But sth is really wrong no way to get a section only considered by the -isa- and the other by -i2c-, whatever I tried both sections were submitted to the same filtering rules :-(

Last resort was to change the output of sensors when called by munin:
 In /etc/munin/plugin-conf.d/munin-node:
[sensors_]
env.sensors=sensors|sed '1,+14d'

====Other plugins====
More info on plugins incl. how to write yours: http://munin.projects.linpro.no/wiki/plugins

Munin

2006-11-29T21:35:06Z

85.234.199.11:

Munin is a nice Monitoring framework

==Sites==
* http://munin.projects.linpro.no/
* http://www.debian-administration.org/articles/229
* http://www.debianhelp.co.uk/munin.htm

==Installation==
===On the collector===
apt-get install munin libdate-manip-perl
Configure /etc/munin/munin.conf to add nodes to collect
===On each node===
apt-get install munin-node libnet-snmp-perl libio-socket-ssl-perl libcrypt-des-perl libdigest-hmac-perl libio-socket-inet6-perl libwww-perl libnet-irc-perl smartmontools ethtool
Maybe you will have to relax the firewall when installing munin otherwise install will stall during plugin detection if loopback connections to port 3128 are dropped.
 Bind the monitor only to the wanted IP in /etc/munin/munin-node.conf and tell which server can get the info:
host <my_ip>
allow ^<regex IP of the collector>$ (see examples)
Select plugins from /usr/share/munin/plugins by adding a symlink in /etc/munin/plugins
 To know if a plugin could work, try it with argument "autoconf", if it says yes then it is usable otherwise look inside the plugin code (perl) for hints.
 Some plugins require some options to be configured, do that in /etc/munin/plugin-conf.d/munin-node

====apache_* plugin====
Activate apache2 extended status (cf http://www.debian-administration.org/articles/161):
 Install mod_info:
a2enmod info
Activate in /etc/apache2/apache2.conf the section:
<Location /server-status> etc
and add just above this section the following line:
ExtendedStatus On

/etc/init.d/apache2 force-reload
Add to /etc/munin/plugin-conf.d/munin-node:
<pre>
[apache_*]
env.lrrd_url "http://<my_ip>:%d/server-status?auto"
</pre>
====ip_ plugin====
Add to /etc/munin/plugin-conf.d/munin-node:
[ip_*]
user root
Add iptables dummy rules to collect stats on a particular IP:
iptables -A INPUT -d <ip>;iptables -A OUTPUT -s <ip>
Install the plugin for this ip:
ln -s /usr/share/munin/plugins/ip_ /etc/munin/plugins/ip_<ip>

====sensors_ plugin====
Usually you create symlinks calles sensors_fan, sensors_volt and sensors_temp.

I had many troubles after a kernel upgrade:
 Now the output of "sensors" features a "phantom" chip w83627hf-i2c-0-28 with no valid values, aside the 2 others, w83782d-i2c-0-29 and w83627hf-isa-0290.
 One more or less correct way would be to e.g. add an entry at the end of /etc/sensors.conf with
chip "w83627hf-i2c-*"
ignore in0
...
But sth is really wrong no way to get a section only considered by the -isa- and the other by -i2c-, whatever I tried both sections were submitted to the same filtering rules :-(

Last resort was to change the output of sensors when called by munin:
 In /etc/munin/plugin-conf.d/munin-node:
[sensors_]
env.sensors=sensors|sed '1,+14d'

====Other plugins====
More info on plugins incl. how to write yours: http://munin.projects.linpro.no/wiki/plugins

2006-11-29T21:20:41Z

85.234.199.11: /* Server side */

==Security==
* [[Forensics]]
* [[Bypass Proxy]]
** [[Bypass Proxy reference]]
* [[MiscCrypto]]
** [[Encfs]]
** [[LoopCrypt]]
* [[Reverse Cross-Site Request (RCSR) vulnerability]]

==Hobbies==
* [[Photo]]
* [[Linux Certification]]
==Hardware==
* [[bttv]]
* [[Canon EOS]]
* [[Kiss 450]]
* [[Laptop Asus]]
* [[Laptop Dell Latitude D600]]
* [[Laptop Dell Latitude D610]]
* [[Photo Frame]]
* [[Philips Webcam]]

==Software==
===Server side===
* [[Apache]]
* [[CVS and Subversion]]
* [[MediaWiki]]
* [[Mysql]]
* [[Gallery]]
* [[PhpMyAdmin]]
* [[Webcalendar]]
* [[Avimanager]]
* [[Munin]]
====Mail services====
* [[qmail & ezmlm]]
* [[Exim]]
* [[Courier]]
* [[Procmail]]
* [[Imapproxy]]
* [[Squirrelmail]]
* [[Spamassassin]]
* [[Fetchmail]]
* [[Anti-Virus]]
====Jabber====
* [[Jabberd]]
* [[Jabberd-Addons]]
* [[Jabberd-Conference]]
* [[Jabberd-Jud]]
* [[Jabberd-AIM]]
* [[Jabberd-Icq]]
* [[Jabberd-Irc]]
* [[Jabberd-MSN]]
* [[Jabberd-Yahoo]]

===Desktop side===
* [[Dict Applications]]
* [[Screen Tips]]
* [[Firefox Tips]]
* [[Bash Tips]]
* [[Mail Tips]]
* [[Offlineimap]]
====[[Jabber]]====
* [[Jabber Clients]]
* [[Jabber Send Message]]
* [[Jabber Utils]]

===Debian===
* [[Debian Documentation]]
* [[Debian Commands]]
* [[DebTags]]
* [[Debian Alsa]]
* [[Debian Kernel]]
* [[Debian Soft Raid]]

==Lifeware==
* [[whoami]]
* [[Bébé]]
* [[Chassis Couronne]]
* [[Prêts et emprunts]]

==Misc==
* [[External links]]

Screen Tips

2006-11-16T22:50:21Z

85.234.199.11:

==Introduction==
Some usages of "screen", a very powerful tool!

To create a screen session
screen

The shortcut to access screen commands is CTRL-a
 There you can create other windows with CTRL-a c
 Go to next window with CTRL-a n

If the link is broken (kill xterm, ssh fails,...) no prob the session is still runnind detached from any terminal.
 You can also detach with CTRL-a d
 To resume a detached session:
screen -r
 To see the list of sessions:
screen -ls
 To remotely force a session to be detached and attach it here:
screen -r -d
 To attach without first detaching an active session:
screen -x
 Very powerful, this last one!!
 For example, helping a friend via remote administration:
* ask him to install screen (of course), create a user for you, so you can log in and change your passwd
* ask him, being root in a xterm, to launch ''su your_username -c "xterm -e screen" &''
* you launch ''screen -x'' from your ssh session and now you are both on the same console!
* you type ''su'' and he types the root passwd, so now you can be momentaneously root on his machine, he did not have to discard root password and he can watch (and learn) what you are doing.

==Multisession==
To allow other users to join your session:
 Gives +s to screen bin:
chmod +s /usr/bin/screen
From screen session:
CTRL-a :
multiuser on
CTRL-a :
addacl user2

It adds user2 to the list of authorized users with full access (partial acces is possible, cf man)
 Then user2 can connect to screen session of user1 with
screen -x user1/
To see the list of sessions of another user:
screen -ls user1/
==Tips==
Sometimes when using __mc__ through screen the graphical characters mess up the layout.
 Try "mc -a", it should fix it.
==Guy notes==

screen: to start screen
screen -r: to reattach to a session
screen -x: to attach to a not detached screen session (multi display mode)
screen -d -r: to remotely force a session to be detached and attach it here
(to cleanly reattach from another session)
screen -D -R: Attach here and now.
In detail this means: If a session is running, then reattach.
If necessary detach and logout remotely first.
If it was not running create it and notify the user.
This is the author's favorite.

C-a d: to detach from the session
C-a ?: to obtain a list of commands
C-a x: to lock your current session
C-a a: to obtain "Ctrl-a" (for emacs for example)
C-a A: to set the title of the newly created window while in screen
(equivalent to screen -t name_of_window)
C-a c: to create new window
C-a k: to remove the current window from the list and forcibly
terminate whatever programs were running in it
C-a C-a: to switch between screen's windows
C-a n: to switch to the next window
C-a p: to switch to the previous window
C-a N: to switch to the corresponding window (N in [0,9])
C-a ": to get a full-screen list of windows
C-a w: to get a small, non-interactive list of windows

C-a S: to split the region in two
C-a tab: to switch from on region to the other one
C-a N: to display any of your window in the current region (N in [0,9])
C-a c: to create a new shell in the current region
C-a Q: to make the current region the only one visible
C-a X: to kill the current region (and the programs running in it)

C-a [: to enter "copy mode"
C-a ]: to paste the text previously copied

C-a _;: to start or stop monitoring the current window for 30 seconds of silence
C-a M: to start or stop monitoring the current window for activity

C-a C-\: to force closing of screen (not recommended)

===Remark 1: collaborative session===
One other good use for the detach and reattach is as a console-mode "remote desktop" feature.
 You can detach from a screen session at work, shell into the machine from home, and reattach.
 With a bit of extra work, you can even have a number of terminals all attached to the same session
(great for collaborative efforts and meetings).

For example, helping a friend via remote administration:
* ask him to install screen (of course), create a user for you, so you can log in and change your passwd
* ask him, being root in a xterm, to launch
su your_username -c "xterm -e screen" &
* you launch screen -x from your ssh session and now you are both on the same console!
* you type su and he types the root passwd, so now you can be momentaneously root on his machine, he did not have to discard root password and he can watch (and learn) what you are doing.

Also:
C-a :multiuser on : to activate multiuser mode
C-a :achchg username +rwx "#" : to give permission to username to connect
Be especially careful with the execute permission as that will let other people create new windows and change the acl permissions themselves.

Now the user you granted access to can connect with:
$ screen -r stan/

At any time, you can delete other users with acldel username

===Remark 2: allowing other users to join your session===
chmod +s /usr/bin/screen: to allow other users to join your session

From screen session:

CTRL-a :
multiuser on
CTRL-a :
addacl user2

It adds user2 to the list of authorized users with full access (partial acces is possible, cf man)
 Then user2 can connect to screen session of user1 with
screen -x user1/

To see the list of sessions of another user:
screen -ls user1/

===Remark 3: bunch of screens at startup===
If you want a bunch of screens at startup, edit your ~/.screenrc.

shell -$SHELL
screen -t SHELL0 0
screen -t ROOT 1
screen -t SHELL2 2
screen -t SHELL3 3
screen -t SHELL4 4
screen -t SHELL5 5

The first line starts the current $SHELL in login mode.
 The others set up six windows and gives them titles.

===Remark 4: logging===
Screen is also capable of logging to files, but that's beyond the scope of this tutorial.

===Remark 5: Customizing screen -> $HOME/.screenrc===
Here's a short example $HOME/.screenrc file containing comments for each directive:

# set some options
activity "activity: window ~%" # Message when activity occurs in a window
vbell_msg "bell: window ~%" # Message for visual bell
vbellwait 2 # Seconds to pause the screen for visual bell
allpartial off # Refresh entire screen on window change
autodetach on # Autodetach session on hangup instead of
# terminating screen completely
bufferfile /tmp/screen-buffer # Filename for the paste buffer
chdir # Change to the home directory
escape "``" # Redefine the prefix key to ` and define a
# literal ` as ``
shelltitle $HOST # Set the title of all shell windows
defflow off # Set the default flow control mode
defmode 0620 # Set the default mode of each pseudo tty
defscrollback 200 # Set the default number of scrollback lines
deflogin off # Do not register the window in utmp
startup_message off # Disable startup messages

# virtual windows to start when screen starts
screen -t emacs@$HOST -h 0 1 /usr/local/bin/emacs -nw
# Start emacs in window 1 with a scrollback
# buffer of 0
screen -t bash@$HOST -ln -h 100 2
# Start a shell with the title of
# tcsh@. turn off login mode
# (remove the window from utmp). Use a
# scrollback of 100 lines and start the shell
# in window 2 (or the next available window)
monitor on # Monitor the above shell window

# keymap for use with the prefix key (backquote)
bind ' ' windows # Show listing of all windows
bind 'a' prev # Previous window
bind 'c' copy # Copy paste buffer
bind 'e' screen -t emacs@$HOST -h 0 1 /usr/local/bin/emacs -nw
# Create new emacs window
bind 'i' info # Show info about the current window
bind 'n' next # Next window
bind 's' screen -t bash@$HOST -ln -h 100 # Create new shell window

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Screen Tips