Reset gnome settings on Ubuntu

if you delete gnome panels accidently, these steps can help you reset all your gnome settings to default

1. logout

2. ctrl + alt + f1 to terminal console

3. rm -rf .gnome .gnome2 .gconf .gconfd .metacity

4. ctrl + alt + f7 to gui desktop

5. login

Set up MRTG on Ubuntu

1. MRTG( Multi Router Traffic Grapher ) working depends on SNMP( Simple Network Management Protocol )

sudo apt-get install apache2 snmpd mrtg

2.

vi /etc/snmp/snmpd.conf
--
..
# sec.name source community
#com2sec paranoid default public
com2sec readonly default public
#com2sec readwrite default private
..

3. use cfgmaker command to create a mrtg config file

# public is the community name set in step 2
cfgmaker public@localhost > /etc/mrtg.cfg

4. creat mrtg webpages by using indexmaker to read mrtg con

indexmaker /etc/mrtg.cfg > /var/www/mrtg/index.html


Load IPTables rules while booting on Ubuntu

1. make you rules as a script

vi /root/firewall.start

2. make another script to flush all rules and allow all connections

vi /root/firewall.stop
--
echo "Stopping firewall and allowing everyone..."
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT

3. chmod 700 /root/firewall.*

4. load rules

sudo /root/firewall.start


5. use iptables.save to save rules as a formatting file for iptables-restore

sudo sh -c "iptables-save > /etc/iptables.rules"

# restore rules with iptables-restore
# sudo iptables-restore < /etc/iptables.rules


6. to restore configuration on startup, the suggested method is to use ifup.d networking scripts, which are executed on state changes of the network interfaces.

sudo vi /etc/network/if-pre-up.d/iptables

--
#!/bin/sh

# Load iptables rules before interfaces are brought online
# This ensures that we are always protected by the firewall
#
# Note: if bad rules are inadvertently (or purposely) saved it could block
# access to the server except via the serial tty interface.
#

RESTORE=/sbin/iptables-restore
STAT=/usr/bin/stat
IPSTATE=/etc/iptables.rules

test -x $RESTORE || exit 0
test -x $STAT || exit 0

# Check permissions and ownership (rw------- for root)
if test `$STAT --format="%a" $IPSTATE` -ne "600"; then
echo "Permissions for $IPSTATE must be 600 (rw-------)"
exit 0
fi

# Since only the owner can read/write to the file, we can trust that it is
# secure. We need not worry about group permissions since they should be
# zeroed per our previous check; but we must make sure root owns it.
if test `$STAT --format="%u" $IPSTATE` -ne "0"; then
echo "The superuser must have ownership for $IPSTATE (uid 0)"
exit 0
fi

# Now we are ready to restore the tables
$RESTORE < $IPSTATE

7. make the rules safer with permission change and make this script executable

sudo chmod 600 /etc/iptables.rules
sudo chmod +x /etc/network/if-pre-up.d/iptables


Wake up computer on Lan from Ubuntu

1. ethtool is a net driver diagnostic and tuning tool for linux. using it to check the network card settings

sudo ethtool eth0
--
.
Wake-on: d
.

2. change wake-on setting to g (Wake on MagicPacket)

sudo ethtool -s eth0 wol g

3. install etherwake, a tool to send magic Wake-on-LAN packets

sudo apt-get install etherwake

4. create a file which lists mac and hostname/ip pairs

sudo vi /etc/ethers
--
MAC_ADD Hostname
MAC_ADD IP_ADD

5. send wol to your target host

sudo etherwake MAC_ADD
# or hostname you have specifed


Set up OpenVPN between Ubuntu and Windows

1. OpenVPN is a full-featured open source SSL VPN solution so you need to install OpenSSL too.

sudo apt-get install openvpn openssl

2. there is a small RSA key management package that can be found in the easy-rsa subdirectory of the OpenVPN distribution. make a copy in /etc/openvpn

sudo cp -r /usr/share/doc/openvpn/examples/easy-rsa /etc/openvpn

3. change working directory to /etc/openvpn/easy-rsa/2.0 and become superuser

sudo su

4. change below fields in variable file

vi vars
--
export KEY_COUNTRY="TW"
export KEY_PROVINCE="Taiwan"
export KEY_CITY="Taipei"
export KEY_ORG="GAMER"
export KEY_EMAIL="luke@luke-server"

5. initialize the PKI. you must enter something for common name when it prompt.

. ./vars
./clean-all
./build-ca

6. build server key

./build-key-server server_name

6. repeat this step to build keys for each different client

# with password
./build-key client_name
# without password
./build-key-pass client_name

7. Diffie Hellman parameters must be generated for the OpenVPN server.

./build_dh

8. copy sample config file from http://openvpn.net/index.php/documentation/howto.html#server then edit it

vi /etc/openvpn/server.conf
--
#################################################
# Sample OpenVPN 2.0 config file for #
# multi-client server. #
# #
# This file is for the server side #
# of a many-clients <-> one-server #
# OpenVPN configuration. #
# #
# OpenVPN also supports #
# single-machine <-> single-machine #
# configurations (See the Examples page #
# on the web site for more info). #
# #
# This config should work on Windows #
# or Linux/BSD systems. Remember on #
# Windows to quote pathnames and use #
# double backslashes, e.g.: #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
# #
# Comments are preceded with '#' or ';' #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one. You will need to
# open up this port on your firewall.
port 1194

# TCP or UDP server?
;proto tcp
proto udp

# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one. On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key). Each client
# and the server must have their own cert and
# key file. The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys. Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
key /etc/openvpn/easy-rsa/2.0/keys/server.key # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh1024.pem 1024
# Substitute 2048 for 1024 if you are using
# 2048 bit keys.
dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file. If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface. Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0. Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients. Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Push routes to the client to allow it
# to reach other private subnets behind
# the server. Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
# iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN. This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
# ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients. There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
# group, and firewall the TUN/TAP interface
# for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
# modify the firewall in response to access
# from different clients. See man
# page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# the TUN/TAP interface to the internet in
# order for this to work properly).
# CAVEAT: May break client's network config if
# client's local DHCP server packets get routed
# through the tunnel. Solution: make sure
# client's local DHCP server is reachable via
# a more specific route than the default route
# of 0.0.0.0/0.0.0.0.
;push "redirect-gateway"

# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
;push "dhcp-option DNS 10.8.0.1"
;push "dhcp-option WINS 10.8.0.1"

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names. This is recommended
# only for testing purposes. For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120

# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
# openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
cipher BF-CBC # Blowfish (default)
;cipher AES-128-CBC # AES
;cipher DES-EDE3-CBC # Triple-DES

# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody
;group nobody

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it. Use one
# or the other (but not both).
log openvpn.log
;log-append openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3

# Silence repeating messages. At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20

9. start openvpn server

sudo /etc/init.d/openvpn start

11. download and install windows package of openvpn from http://openvpn.net/index.php/downloads.html
12. copy necessary key and certificate to the client computer. for windows machine, files go to C:\Program Files\OpenVPN\config

ca.crt
client.key
client.crt

13. double click on the client configuration file to edit it, C:\Program Files\OpenVPN\config\client.ovpn

##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server. #
# #
# This configuration can be used by multiple #
# clients, however each client should have #
# its own cert and key files. #
# #
# On Windows, you might want to rename this #
# file so it has a .ovpn extension #
##############################################

# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client

# Use the same setting as you are using on
# the server.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel
# if you have more than one. On XP SP2,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap

# Are we connecting to a TCP or
# UDP server? Use the same setting as
# on the server.
;proto tcp
proto udp

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote IP PORT
;remote my-server-2 1194

# Choose a random host from the remote
# list for load-balancing. Otherwise
# try hosts in the order specified.
;remote-random

# Keep trying indefinitely to resolve the
# host name of the OpenVPN server. Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite

# Most clients don't need to bind to
# a specific local port number.
nobind

# Downgrade privileges after initialization (non-Windows only)
;user nobody
;group nobody

# Try to preserve some state across restarts.
persist-key
persist-tun

# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here. See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]

# Wireless networks often produce a lot
# of duplicate packets. Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings

# SSL/TLS parms.
# See the server config file for more
# description. It's best to use
# a separate .crt/.key file pair
# for each client. A single ca
# file can be used for all clients.
ca ca.crt
cert client.crt
key client.key

# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server". This is an
# important precaution to protect against
# a potential attack discussed here:
# http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server". The build-key-server
# script in the easy-rsa folder will do this.
;ns-cert-type server

# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1

# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x
cipher BF-CBC

# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo

# Set log file verbosity.
verb 3

# Silence repeating messages
;mute 20

14. right click on client.ovpn then click Start "OpenVPN on this config file"

Monitor CPU Temperature / Voltage / Fan Speed on Ubuntu

1. install lm-sensors which is Linux Hardware Monitoring

sudo apt-get install lm-sensors

2. run sensors-detect to find out all possible hardware health sensors, it is recommended to accept the default answers to all questions.

sudo sensors-detect


#----cut here----
# Chip drivers
w83627hf
#----cut here----

3. according to the result, manually load the necessary modules.

sudo modprobe w83627hf

4. now you can get the hardware information by the command, sensors

Make chinese display support module on Slax

1. create directories which match to system path

mkdir -p etc/rc.d
mkdir -p usr/share/fonts/TTF

2. download chinese font, fireflysung.ttf for open-source platform then put it into usr/share/fonts/TTF

3. create a script which can be run while booting

vi etc/rc.d/rc.local

fc-cache -f -v
cd /usr/share/fonts/TTF
mkfontscale
cp fonts.scale fonts.dir

4. pack them all to a lzm module

dir2lzm ./ filename.lzm

5. move the module to /slax/modules of your native partition for automatic activation