Linux Running level

There 7 running level in Linux system:

• rc0.d - System Halted
• rc1.d - Single User Mode
• rc2.d - Single User Mode with Networking
• rc3.d - Multi-User Mode - boot up in text mode
• rc4.d - Not yet Defined
• rc5.d - Multi-User Mode - boot up in X Windows
• rc6.d - Shutdown & Reboot

To check which program are running at which level use command chkconfig --list.

Usefull word in IT tech doc

A

adjacent: [ә'dʒeisәnt]adj. 毗连的, 邻近的, 连接的 be adjacent to...
anomaly: [ә'nɒmәli] n, anomalous thing; irregularity
anomalous: [ә'nɒmәlәs] adj. different from what is normal; irregular

E
erratic: *[i'rætik] adj, irregular or uneven in movement,quality or behaviors; unreliable

Let non-root user can reboot linux box

There are one command called sudo could allow normal linux user execute root command. The configuration file or sudo command is /etc/sudoers and the configuration file should only be modified by using visudo command. For example we creat a group called shutdown. Following line will allow all shutdown group user can use sudo shutdown the linux box.

%shutdown ALL=(root) NOPASSWD: /sbin/reboot
%shutdown ALL=(root) NOPASSWD: /sbin/halt
%shutdown ALL=(root) NOPASSWD: /sbin/shutdown

usermod command can add user to other group.

Options:

* -d home directory
* -s starting program (shell)
* -p password
* -g (primary group assigned to the users)
* -G (Other groups the user belongs to)

Example: To add the group 'others' to the user roger

usermod -Gothers roger

chgrp, chown command can change the group. chgrp can be used by normal user

*

chgrp group target1

* chown [-R] newowner filenames


Example:Give permissions as owner to user test.
chown test files.log

Clean up SQL database use command line tools

There are some SQL server command line tools are installed in C:\Program Files\Microsoft SQL Server\80\Tools\Binn folder. OSQL.exe can connect to the database and execute SQL query on it.

The usage of OSQL.exe is
OSQL /u username
system will pop up for password, after authentication. we can type in SQL query and execute them on the server.
for example

To release unused database space:
DBCC SHRINKDATABASE (local, 80 TRUNCATEONLY)
GO

To find a database name:
select db_name(0) [0 is the database index number]
Go

Juniper Router Interface Naming:

Juniper router interface naming based on model:

• “media type-FPC number/PIC number/port number” It commonly knows as MM-F/P/T model for M series router.

• “media type-PIM slot number/virtual PIM number/port number, It commonly knows as MM-F/P/T for J series router. Fixed interface use PIM slot number 0.

FPC - Flexible PIC Concentrator which contain several PIC slots (on M series)

PIC – Physical Interface Card

PIM – Physical Interface Module (on J series) Each PIM contains a network processor that handles some of the packet processing functions.

• at: ADSL interface;

• dsc: Virtual interface that discards packets;

• fxp0: This is an Out of Band (OOB) management Ethernet interface. It is connected to the router's Routing Engine (RE) and can be used for Out of Band management access to the router. It can also be used to send management messages such as syslog or Simple Network Management Protocol (SNMP) traps. This interface is a nontransit interface, which means that traffic cannot enter this interface and exit via a LAN/WAN interface, nor can it enter a LAN/WAN interface and exit through the management interface.

• fxp1: This is an internal Fast Ethernet or Gigabit Ethernet (depending on the model of router) interface between the RE and the Packet Forwarding Engine (PFE). This interface is never configured but can be helpful when troubleshooting router issues. It is only in application-specific integrated circuit (ASIC) platforms (M/T-series) and not in the virtualized PFE J-series platforms.

• e1: E1 WAN interface;

• fe: Fast Ethernet(10/100) LAN interface;

• ge: Gigabit Ethernet (10/100/1000) LAN interface;

• gr,gre: Generic touting encapsulation (GRE) interface for tunnel services-this interface is internally generated and not configurable;

• ip, ipip: IP-over-IP interface-this interface is internally generated and not configurable;

• ls, lsi: link services interface- this interface is internally generated and not configurable;

• mt, mtun: Muticast GRE interface-this interface is internally generated and not configurable;

• pd, pimd: Protocol Independent Multicast(PIM) de-encapsulator interface-this interface is internally generated and not configurable;

• pe, pime: PIM encapsulator interface-this interface is internally generated and not configurable;

• pp: Point-to-point Protocol(PPP) interface-used for PPP over Ethernet (PPPoE);

• se: Serial interface(include EIA230, RS232, RS449, V.35 and X.21 interfaces);

• sp: Services interface;

• tap: The tap interface is internally generated and not configurable;

• t1: T1 (also called DS1) WAN interface;

• t3: T3 (also called DS3) WAN interface;

Windows Remote Desktop Firewall Setting

open port 3389 for TCP+UDP connection.

Display CPU info in Linux

cat /proc/cpuinfo
cat /proc/meminfo
dmesg
lspci

Known Attack

zero-day (or zero-hour) attack or threat is a computer threat that tries to exploit computer application vulnerabilities that are unknown to others, undisclosed to the software vendor, or for which no security fix is available. Zero-day exploits (actual code that can use a security hole to carry out an attack) are used or shared by attackers before the software vendor knows about the vulnerability.

website log analysis for website which host on www.net.cn

1. Download the website log file follow the downloading instruction from www.net.cn
[管理主机] 通过控制面板，配置WebLog日志下载说明 [客服中心][2006年3月16日][6920]

简介：无
内容：
当 您想查看站点的详细的WebLog日志时，可以通过此功能将您想查看的一段时间内日志文件先拷到您站点的wwwlogs目录下，您可以通过FTP的方式将 日志文件下载到您本地进行查看。　　注意：　　1、由于日志文件较大，当您将日志文件下载到本地后，将您站点的wwwlogs目录下的文件删除，以便节省 您的Web空间。　　2、我们只提供一周内的日志文件下载。……
2 Download and install weblog expert from the link blow

http://www.weblogexpert.com/files/WLELiteSetup.exe

3. run the weblog expert. In software window. press new button and input the profile name with any thing you like, domain with your website address, index with the main page of your website. And than press next

4. Press browse button and select the log file which you just download from net.cn and press finish

5 select the profile which you just created and press analyze button now a analysis report would show on your default browser.

Linux NIC bonding

Configuration files:
/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/sysconfig/network-scripts/ifcfg-eth1
/etc/sysconfig/network-scripts/ifcfg-bond0
/etc/modprobe.conf
/proc/net/bonding/bond0

Files contant:

• /etc/sysconfig/network-scripts/ifcfg-eth0
  DEVICE=eth0
  USERCTL=no
  ONBOOT=yes
  MASTER=bond0
  SLAVE=yes
  BOOTPROTO=none
  ETHTOOL_OPTS="speed 1000 duplex full autoneg on"
  
• /etc/sysconfig/network-scripts/ifcfg-eth2
  DEVICE=eth2
  USERCTL=no
  ONBOOT=yes
  MASTER=bond0
  SLAVE=yes
  BOOTPROTO=none
  ETHTOOL_OPTS="speed 1000 duplex full autoneg on"
  
• /etc/sysconfig/network-scripts/ifcfg-bond0
  DEVICE=bond0
  IPADDR=192.168.100.20
  NETMASK=255.255.255.0
  NETWORK=192.168.100.0
  BROADCAST=192.168.100.255
  ONBOOT=yes
  BOOTPROTO=none
  USERCTL=no
• /etc/modprobe.conf
  alias eth0 e1000
  alias eth1 tg3
  alias bond0 bonding
  options bond0 miimon=100 mode=5
  

Bonding mode:

mode=0 (balance-rr)
Round-robin policy: Transmit packets in sequential order from the first available slave through the last. This mode provides load balancing and fault tolerance.

mode=1 (active-backup)
Active-backup policy: Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond's MAC address is externally visible on only one port (network adapter) to avoid confusing the switch. This mode provides fault tolerance. The primary option affects the behavior of this mode.

mode=2 (balance-xor)
XOR policy: Transmit based on [(source MAC address XOR'd with destination MAC address) modulo slave count]. This selects the same slave for each destination MAC address. This mode provides load balancing and fault tolerance.

mode=3 (broadcast)
Broadcast policy: transmits everything on all slave interfaces. This mode provides fault tolerance.

mode=4 (802.3ad)
IEEE 802.3ad Dynamic link aggregation. Creates aggregation groups that share the same speed and duplex settings. Utilizes all slaves in the active aggregator according to the 802.3ad specification.

 Pre-requisites:  1. Ethtool support in the base drivers for retrieving  the speed and duplex of each slave.  2. A switch that supports IEEE 802.3ad Dynamic link  aggregation.  Most switches will require some type of configuration  to enable 802.3ad mode.

mode=5 (balance-tlb)
Adaptive transmit load balancing: channel bonding that does not require any special switch support. The outgoing traffic is distributed according to the current load (computed relative to the speed) on each slave. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed receiving slave.

 Prerequisite:  Ethtool support in the base drivers for retrieving the  speed of each slave.

mode=6 (balance-alb)
Adaptive load balancing: includes balance-tlb plus receive load balancing (rlb) for IPV4 traffic, and does not require any special switch support. The receive load balancing is achieved by ARP negotiation. The bonding driver intercepts the ARP Replies sent by the local system on their way out and overwrites the source hardware address with the unique hardware address of one of the slaves in the bond such that different peers use different hardware addresses for the server.

The most used are the first four mode types...

Also you can use multiple bond interface but for that you must load the bonding module as many as you need.
Presuming that you want two bond interface you must configure the /etc/modules.conf as follow:

 alias bond0 bonding  options bond0 -o bond0 mode=0 miimon=100  alias bond1 bonding  options bond1 -o bond1 mode=1 miimon=100

Install vmware tool on the ubuntu 9.04

Command list:
sudo aptitude install build-essential linux-headers-generic


sudo touch /usr/src/linux-headers-`uname -r`/include/linux/config.h

cp /media/cdrom/VMwareTools-*.tar.gz ~\Desktop\

cd ~\Desktop\

tar xf VMwareTools-*.tar.gz

cd vmware-tools-distrib/

sudo ./vmware-install.pl -d

Reference:
Ubuntu community document about vmware https://help.ubuntu.com/community/VMware

How To Install VMware Tools on Ubuntu 8.04 Guests https://help.ubuntu.com/community/VMware

Linux hard disk operation

LVM
Create LV process

• Initializing disks or disk partitions

  fdisk - fdisk /dev/sd? press p to list the partition table, press n to create a new partition, press e to create extended partition, press p to create a primary partition(maximum 4 per disk) input the number of the partition if create a primary partition, input fisrt cylinder number, input last cylinder number or +sizeM eg: +100M. Change the partition's system ID by use the fdisk command t, input the partition number after the popup Selected Partition, input desired Hex code of the system id here input 8e which for linux LVM. Use the fdisk command w to write the new partition table to the hard disk.

• Assign the disks or disk partitions as physical volume
• Create volume group on one or more PVs
• Use space from a VG as Logical Volume
• Format the LV.

Linux harddisk and NIC test command

hdparm -Tt /dev/hd* test the hdd read speed and system cache speed.

ethtool is used for querying settings of an ethernet device and changing them.

Reduce The Size Of SQL Server Transaction Log

Introduction
To stop the nightmare of low disk space which cased by huge transaction log file. There three things to do. First truncate the inactive items in the transaction log. However it does not reduce the size of the log file. Secondly shrink the transaction log file. Finally, If possible set a fix maximum size of the transaction log file.

Truncate the inactive items in the transaction log
There are two ways to truncate the transaction log. Doing backup transaction log in the enterprise manager and truncate the transaction log by using T-SQL command.

Using SQL server enterprise manager to backup the transaction log will automatically truncate the inactive transactions after the backup. By doing this you need:
* Open the enterprise manager from the desktop shortcut or start menu.
* In the enterprise manager expend following items in the Console Root tree one by one: Microsoft SQL Servers, SQL Server Group, The database server which need perform backup task, Databases.
* Right click the database name and point to All Tasks, and then select Backup Database.
*Fill in the task name and description
* Click the radio button in front of the Transaction Log which in the backup section.
*In the Overwrite section choose Append to media or Overwrite existing media.
* Go to the Option tab make sure Remove inactive entries from transaction log has been selected.

If there are no enough space on the backup device or the backup of transaction log is not necessary. Executing truncate command in SQL Query Analyzer could be more straightforward.
* Open SQL Query Analyzer from start menu or executing the isqlw utility
* Select database which need truncate transaction log.
* Type in following T-SQL command:
use database name
BACKUP LOG WITH TRUNCATE_ONLY
* Press the execute button.

Shrinking the transaction log

Execute following command in the SQL Query Analyzer.

USE DatabaseName
DBCC SHRINKFILE(transaction log file name,desired shrink size in MB)


Fix the maximum size of the transaction log so you do not need worry about it again.

Open the enterprise manager from the desktop shortcut or start menu.
* In the enterprise manager expend following items in the Console Root tree one by one: Microsoft SQL Servers, SQL Server Group, The database server which need perform backup task, Databases.
* Right click the database name and point to Properties.
* Go to Transaction Log tab in the Database Properties window.
* Select Restrict file growth(MB): and fill in the size.

Eclipse Code Template

In eclipse we can input a template name and than press a key combination to quickly input big code block. For example we can type in "sysout" and press the default content assist key "Ctrl + space" to input "system.out.println()".

To do this you need check what template eclipse have by click window -> preference.

Linux Network management

/etc/modprobe.conf -- contain a list of alias name for each NIC
dmesg | grep "NIC name" and ifconfig can display the hardware address of NIC.
mii-tool - view and config negotrated speed of NIC, but it not support all the NICs. "mii-tool -v" can tell wheather the NIC support mii-tool.
ifdown and ifup
kudzu
netconfig - can create ifcfg-*** file. "netconfig --device eth1" config eth1 NIC.
system-config-network
/etc/sysconfig/network-scripts/ifcfg-*** - configuration file for each NIC *** represent NIC alias name.

/etc/resolv.conf contain DNS setting

Linux Kernel

Kernel Modules
Kernel Modules are locate in /lib/modules directory.

lsmod, list current mounted modules.
modprobe , mount specific modules and dependencies.
/sbin/modinfo , module examination
insmod, mount module
rmmod, unmount module
depmod, list module dependencies.

Configure Kernel Modules by modify /etc/modprobe.conf which structure is aliases, kernel parameters, Module mount actions.

Module dependencies record in modules.dep

/proc/sys

Linux Installation

type in "linux askmethod " and Enter after "boot:" will let installer ask for install method (from CD, harddisk, NFS, FTP or HTTP)

Partition:

Note:

• /etc, /lib, /sbin, /dev and /(root directory) must in one partition.
• swap directory is normally two times of the size of the RAM.
• /boot, /home, /usr, /var, /tmp, /urr/local, /opt could be used as mount points for directory. /boot need no more than 100MB
  

Create software RAID or LVM in Linux installer:

In the partition page of the installer, pressing New button will create a new partition. " In the File system type" chose software RAID or physical volume to setup the special partition. After create software RAID or physical volume, RAID or LVM button can be used to create RAID device or volume group. Moreover when create RAID device, chose physical volume in the file system type will create a physical volume over a RAID device.

Software RAID, RAID principles-http://en.wikipedia.org/wiki/RAID#Principles
LVM Resource Page http://sourceware.org/lvm2/

Verbs with down

bring down:to cause someone in a position of power to lose their job: This scandal could bring down the government.
come down:
hold sb/sth down: to keep someone or something in a particular place or position and to stop them from moving: He was struggling so much that it took three police officers to hold him down.
knock sb/sth down: to cause someone or something to fall to the ground by hitting them
See picture
go down:
put down:
take sth down: 1. (REMOVE) to remove something that is on a wall or something that is temporary, or to remove a structure by separating its different parts: I've taken the pictures down. 2. (WRITE) to write something that another person has just said: He took down my address and phone number and said he'd phone back.

turn sb/sth down: to refuse an offer or request: He offered her a trip to Australia but she turned it/him down. He turned down the job because it involved too much travelling.

Cron in Linux

• Check Cron whether installed in linux: rpm -qa | grep cron
• Start cron service in RHEL, service crond start
• Edit tasks: crontab -e, the task configure structure is
  [Minute] [Hour] [Day of the month] [Month of the year] [Day of the week] [command]
  "*" represent any number. "/" means every. "-" means to. "," separate more than one value eg: */2 2-4 2,5,7 * * means every 2 mins between 2 o'clock and 4 o'clock in the second, fifth and seventh day in each month.
• Del tasks: crontab -r
• List tasks: crontab -l