Asteris video conference

[general]
videosupport=yes

[xxx]
......
allow=h263
allow=h263p

Sync เวลา โดยใช้ ntpd

ติดตั้ง ntpd
#
Redhat/Centos : yum install ntp
Debian/Ubuntu : apt-get install ntp

#
แก้ไขไฟล์ /etc/ntp.conf
โดยประเทศไทยให้ใส่

server 1.th.pool.ntp.org
server 0.asia.pool.ntp.org
server 2.asia.pool.ntp.org

#
Restart ntpd /etc/init.d/ntp restart

20 Network Tools

1: top - Process Activity Command
2: vmstat - System Activity, Hardware and System Information
3: w - Find Out Who Is Logged on And What They Are Doing
4: uptime - Tell How Long The System Has Been Running
5: ps - Displays The Processes
6: free - Memory Usage
7: iostat - Average CPU Load, Disk Activity
8: sar - Collect and Report System Activity
9: mpstat - Multiprocessor Usage
10: pmap - Process Memory Usage
11 and 12: netstat and ss - Network Statistics
13: iptraf - Real-time Network Statistics
14: tcpdump - Detailed Network Traffic Analysis
15: strace - System Calls
16: /Proc file system - Various Kernel Statistics
17: Nagios - Server And Network Monitoring
18: Cacti - Web-based Monitoring Tool
19: KDE System Guard - Real-time Systems Reporting and Graphing
20: Gnome System Monitor - Real-time Systems Reporting and Graphing

from : http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

Object-relational mapping (ORM)

ORM, O/RM, หรือ O/R mapping ย่อมาจาก Object / Relational Mapping หมายถึง การ map ข้อมูลในตารางข้อมูลของฐานข้อมูลให้อยู่ในรูปของ object-oriented language ซึงจะเป็นการสร้าง Database แบบเสมือนขึ้นให้มาอยู่ในรูป language programming ทำให้ไม่ต้องไปยุ่งกับ SQL Statement ซึ่งถ้ามีการเปลี่ยนแปลงแก้ไขต้องแก้ไขที่ตัวโปรแกรมแทน และการกระทำต่างๆยังคงเป็นแบบ Relational เหมือนเดิม

เพิ่มเติม : http://en.wikipedia.org/wiki/Object-relational_mapping

Asterisk Special Variables

Special Variables
Asterisk has some special variables that are automatically defined when a new channel (call) starts up. Later you will see an example of using the ${EXTEN} variable. These definitions come from the README.variables file.

${ACCOUNTCODE} Account code (if specified)
${CALLERID} Caller ID
${CALLERIDNAME} Caller ID Name only
${CALLERIDNUM} Caller ID Number only
${CALLINGPRES} PRI Caller ID presentation for incoming calls
${CHANNEL} Current channel name
${CONTEXT} Current context
${DATETIME} Current date time in the format: YYYY-MM-DD_HH:MM:SS
${DNID} Dialed Number Identifier
${ENUM} Result of application EnumLookup
${EPOCH} Current unix style epoch
${EXTEN} Current extension
${ENV(VAR)} Environmental variable VAR
${HANGUPCAUSE} Asterisk hangup cause
${INVALID_EXTEN} The invalid called extension (used in the "i" extension)
${LANGUAGE} Current language
${LEN(VAR)} String length of VAR (integer)
${MEETMESECS} Number of seconds a user participated in a MeetMe
${PRIORITY} Current priority
${RDNIS} Redirected Dial Number ID Service
${TIMESTAMP} Current date time in the format: YYYYMMDD-HHMMSS
${TXTCIDNAME} Result of application TXTCIDName
${UNIQUEID} Current call unique identifier

${SIPCALLID} SIP Call-ID: header verbatim (for logging or CDR matching)
${SIPDOMAIN} SIP destination domain of an inbound call (if appropriate)
${SIPUSERAGENT} SIP user agent

The dial() application sets the following variables:

${DIALEDPEERNAME} Dialed peer name
${DIALEDPEERNUMBER} Dialed peer number
${DIALEDTIME} Total time for the call in seconds (Network time).
${ANSWEREDTIME} Time from answer to end of call in seconds.
${DIALSTATUS} Status of the call, one of:
CHANUNAVAIL CONGESTION BUSY NOANSWER ANSWER CANCEL

Asterisk CLI

start asterisk
#/etc/init.d/asterisk start

start CLI
#asterisk -r

-v Increase the level of verboseness on the console. The more times
-v is specified, the more verbose the output is.
Specifying this option implies -f and will cause asterisk to no
longer fork or detach from the controlling terminal. This
option may also be used in conjunction with -r and -R.

Note: This always sets the verbose level in the asterisk process,
even if it is running in the background. This will affect the
size of your log files.

Iptables

Block ip address

#iptables -A INPUT -s XXX.XXX.XXX.XXX -j DROP
for example -># iptables -A INPUT -s 221.5.57.124 -j DROP
To save your changes type
#service iptables save
to View your IPTABLE list type
#iptables -L