How to install flash player for firefox/mozilla in Linux (CentOS, RedHat, SuSE, SLES etc)

Just installed linux and can't play YOUTUBE or other flash based programs...... No more scratching heads.
Go to adobe website to download the flashplayer: http://get.adobe.com/flashplayer/

Download the appropriate file based on your OS. (32-bit or 64-bit linux).

I would recommend you to download .tar.gz file of the flashplayer.

Once the file is downloaded, you simply need to extract it. Extract is within the folder.

#mkdir myFlashdir
#cd myFlashdir

copy flashplayer.tar.gz in this folder

#tar xvzf flashplayer.tar.gz

Now you will see libflashplyer.so plugin-file for mozilla. You simply need to copy this file to

/usr/lib64/mozilla/plugins ==> If your linux is 64-bit

/usr/lib/mozilla/plugins ==> If your linux is 32-bit

#cp libflasplayer.so /usr/lib64/mozilla/plugins


You are done. Now have fun with you Youtube or other flash programs.


You can check the plugins installed by typing following in the URL field.

about:plugins

Dell Latitude + Linux : Easy to solve the problem with Wireless setup

Step 1: Download the linux based driver for your NIC card in your Dell Latitude laptop. My laptop has Broadcom Wireless controller. You can check yours by running the command

#lspci |grep -i 802.11

Mine is: Network controller: Broadcom Corporation BCM4321 802.11a/b/g/n (rev 03)
Luckily I found the driver at Broadcom website.

Check if your system has 32-bit Linux or 64-bit Linux and download the appropriate driver. You can check that via

#uname -a

Mine is 64-bit SUSE Linux: Linux devsuse 2.6.32.12-0.7-default #1 SMP 2010-05-20 11:14:20 +0200 x86_64 x86_64 x86_64 GNU/Linux


Step2: Follow README.txt for that driver. It has clear instruction.

[extract from README.txt]

# lsmod  | grep "b43\|ssb\|wl"

If any of these are installed, remove them:
# rmmod b43
# rmmod ssb
# rmmod wl

To blacklist these drivers and prevent them from
loading in the future:
# echo "blacklist ssb" >> /etc/modprobe.d/blacklist.conf
# echo "blacklist b43" >> /etc/modprobe.d/blacklist.conf

>>1. Unzip, build and install the driver
Setup the directory by untarring the proper tarball:

For 32 bit:  hybrid-portsrc_x86-32_v5.100.82.38.tar.gz
For 64 bit:  hybrid-portsrc_x86-64_v5.100.82.38.tar.gz

Example:
# mkdir hybrid_wl
# cd hybrid_wl
# tar xzf /hybrid-portsrc_x86-32_v5.100.82.38.tar.gz

Build the driver as a Linux loadable kernel module (LKM):

# make clean   (optional)
# make

When the build completes, it will produce a wl.ko file in the top level
directory.


>>2: Insmod the driver.

Otherwise, if you have not previously installed a wl driver, you'll need
to add a security module before using the wl module.  Most newer systems
use lib80211 while others use ieee80211_crypt_tkip. See which one works for
your system.

# modprobe lib80211 
  or 
# modprobe ieee80211_crypt_tkip

Then:
# insmod wl.ko

wl.ko is now operational.  It may take several seconds for the Network
Manager to notice a new network driver has been installed and show the
surrounding wireless networks.

Step3. Check if you can see the wireless card detected.
#ifconfig
#iwconfig

or Go to yast2 --> Network Devices --> Network Settings --> Overview
You should see your wireless network card listed.

Step4: Configure your wireless as you do with your regular wireless setup. Good Luck!!!
(You can refer to Novell Documentation if you need any help to configure your Wireless network)

If your internet/network connectivity doesn't wok, check if the routing table is good.

#route -n

You can define the default route for 0.0.0.0 (any) through your wireless interface ( in my case it's eth1). For that you can go to YAST2-->Network Devices-->Network Settings-->Routing

Also make sure that you have DNS servers defined. If not, you can go to YAST2 -->Network Devices-->Network Settings-->Hostname/DNS
or you can also edit /etc/resolv.conf


NOTE: Upgrading the kernel and drivers requires removing ssb, b43 and adding them to the blacklist again.

Directories Terminology: Active Directory, eDirectory, Lotus Domino Directory

LDAP is very often used to access the directories. Directory could be Active Directory, eDirectory/Novell NDS, Lotus Domino Directory and more.
There are too many acronyms like DN, DC, OU, CN, GPO and they are easy to understand

AD: Active Directory
DN : Distinguished Name
DC: Domain Controller/Component
OU: Organizational Unit
CN: Common Name
GPO: Group Policy

Fig. Organization tree structure depicted by AD heirarchy

In Active Directory , eDirectory or any LDAP compliant directory , objects are referred to by Distinguished Name (DN) . The parts of a distinguished name, delimited by commas, represent where in AD hierarchy the object exists.

Monikers in a DN are:

CN Common Name cn=Joe Dirt
OU Organization Unit ou=Staff
DC Domain Controller/Component dc=UPS

An example of the Distinguished Name of a user object could be:

cn=Joe Dirt, ou=Staff, ou=Finance, ou=Dept, ou=UPS, dc=ad, dc=ups, dc=com

In this case, the object with Common Name 'Joe Dirt' is in the Organizational Unit 'Staff', which in turn is in the Organizational Unit 'Finance', which in turn is in the Organizational Unit 'Dept', which in turn is in Organization Unit 'UPS', which is in the domain 'ad.ups.com'.

You can use various free LDAP browsers like Softerra , JXplorer to browse directories.

More examples to clarify the concept:
If you want to refer to all the objects under UPS Organizational Unit/Container, you should use

BASE DN: ou=UPS, dc=ad, dc=ups, dc=com

If you want to refer to all the objects under Finance Organizational Unit/Container, you should use

BASE DN: ou=Finance, ou=Dept, ou=UPS, dc=ad, dc=ups, dc=com

If you want to login as Joe Dirt to make LDAP query, you should use following DN

USER DN: cn=Joe Dirt, ou=Staff, ou=Finance, ou=Dept, ou=UPS, dc=ad, dc=ups, dc=com


CN is used for the default system based containers. OU is also used for containers. One major difference between a CN container and a OU container is that GPOs can be applied only to OUs, not to CNs.

Reference: wiki, forums and various text books

DHCP IPv4 vs IPv6 : Basic concept

Most of us are familiar with DHCP (Dynamic Host Configuration Protocol). We use it all the time to get an IP address and network configurations for our devices like laptop, computers, handheld IP devices, IP TV and more... It makes our life easy as we don't have to manually define the IP address for our system and we also don't have to worry about IP address duplication problem. DHCP takes care all of those for us.

We all know that IPv6 is drilling our internet world and it's going to replace IPv4. There is going to be revolution. DHCP is one of those areas. Architecture of DHCPv4 (IPv4 system) and DHCPv6 (IPv6) are totally different. I will try my best to explain the differences in very easy language.

1. In IPv4 systems, hosts send broadcast traffic requesting an IP address in hope to get reply from the DHCP server, thus network doesn't know how far to send the request.

But all IPv6 systems support multicasting and DHCPv6 servers are ready to receive DHCPv6 multicast packets. Thus network knows where to send the DHCP requests from clients. (FF02::1:2 is a link-scoped multicast address used by a client to communicate with neighboring i.e on-link, relay agents and server. All servers and relay agents are members of this multicast group)

[Wireshark capture for DHCPv6: notice a link-scoped multicast address. I intentionally hid my link-local address(IPv6) of my laptop which acts as IPv6 host ]




2. In IPv4 systems, clients doesn't have any valid IP address to start with. It uses 0.0.0.0 as it's initial IP address and sends request (requesting IP address and network configuration ) broadcast traffic to 255.255.255.255 in hope to get response from DHCP servers.

(Here is the complete DHCPv4 request-reply messaging in IPv4 environment: captured by wireshark using filter BOOTP. DHCPv4 uses BOOTP)



In IPv6 systems, each hosts have valid link-local address that can be used to send traffic on the link it is connected to, thus makes it possible to send request to DHCP server for REAL address.

There are more to talk... But I have to watch NBA finals: MAVS vs Heat. :D
I will keep on updating this article.


Reference:
http://www.ietf.org/rfc/rfc3315.txt
http://www.isc.org/community/blog/201104/isc-dhcp-and-ipv6-dhcpv6-story
http://en.wikipedia.org/wiki/IPv6#Stateless_address_autoconfiguration

Centralized LogServer in SuSE Linux

LogServer: ServerA [IP address: 192.168.1.5]
NetworkServers: ServerB, ServerC... and more

ServerB-------send log files-----> ServerA[LogServer] <-----------send log files---- ServerC

Here we want ServerB, Server C to send it's log file to ServerA for centralized access of log files.

Daemon: syslog-ng
Files:
/etc/sysconfig/syslog
/etc/syslog-ng/syslog-ng.conf

Commands:
/etc/init.d/syslog start|restart|stop

ps aux|grep syslog --> to see if syslog-ng is running or not

SuSEconfig --module syslog-ng --> to reload the change done on /etc/syslog-ng/syslog-ng.conf


Configure LogServer i.e ServerA to accept the log files from NetworkServers

Edit /etc/syslog-ng/syslog-ng.conf on ServerA(Log Server)

source src {
#
# include internal syslog-ng messages
# note: the internal() soure is required!
#
internal();

#
# the default log socket for local logging:
#
unix-dgram("/dev/log");

#
# uncomment to process log messages from network:
#
udp(ip("0.0.0.0") port(514));
#I uncommented above line telling ServerA to accept the log files from network
};


At the bottom of this file, I defined the destination and log

#
#Added by DShah 05/25/11
#
destination std { file("/var/log/HOSTS/$YEAR-$MONTH/$HOST/$FACILITY-$YEAR-$MONTH-$DAY" owner(root) group(root) perm(0600) dir_perm(0700) create_dirs(yes));
};

log { source(src);
destination(std);
};

Over here I am telling ServerA to process the log files coming source src to destination std.
Destination std tells ServerA to save log messages from each host in a separate directory called /var/log/HOSTS/YEAR-MONTH/hostname/.

Now run the command
#SuSEconfig --module syslog-ng --> to reload the config changes done

#/etc/init.d/syslog restart OR
#syslog-ng restart

#ps aux|grep syslog --> to check if syslog-ng is running

If you need to kill syslog-ng process for any reason, you can simply run the command

#killall syslog-ng
or
#kill -9 [PID-of-syslog-ng]

Configure NetworkServers (Server B, ServerC... ) to send log files to LogServer(ServerA):

Edit /etc/syslog-ng/syslog-ng.conf or /etc/syslog-ng/syslog-ng.conf.in (preffered) on ServerB, ServerC

#
#Added by DShah 05/25/2011
#
destination logserver {
udp("192.168.1.5" port(514));
#Note: here 192.168.1.5 is an IP add of LogServer i.e ServerA
};

log {
source(src);
destination(logserver);
};

Now run the command
#SuSEconfig --module syslog-ng --> to reload the config changes done

#/etc/init.d/syslog restart OR
#syslog-ng restart

#ps aux|grep syslog --> to check if syslog-ng is running


ServerA should be already collecting the log files. You can go to /var/log/HOSTS directory on ServerA to see the log files from different Network Servers.

Illustration by Additional applications:
Let's say I want remote asterisk server to dump it's log file /var/log/asterisk/full in the centralized log server
Edit /etc/syslog-ng/syslog-ng.conf or /etc/syslog-ng/syslog-ng.conf.in (preffered) on remote Asterisk Server

#
# Added by DShah
#
source asterisklog { pipe("/var/log/asterisk/full");
};

destination logserver { udp("192.168.1.5" port(514));
};

log { source(asterisklog); destination(logserver); };


and run the command

#syslog-ng restart

Now please check /var/log/HOSTS , you should see log file from asterisk server.


If you need any help on Linux/Unix systems, you can email me at erdevendra@gmail.com with subject title rapidtechguide.

For more info: http://www.novell.com/coolsolutions/feature/18044.html
20 minutes video on syslog-ns : http://www.balabit.com/network-security/syslog-ng/opensource-logging-system/overview#
Syslog-ns to collect apache logs: http://peter.blogs.balabit.com/2010/02/how-to-collect-apache-logs-by-syslog-ng/

SCREEN command: Handy tool for multi-screen session and remote interaction

Screen is the Multi-Screen utility that allows the users to access the multiple screen in single SSH session that allows user to do different tasks on different screens. User doesn't require to open multiple SSH session. However, you need to learn some keyboard short-cuts.

How to start Screen?
# screen -S mySessionName

e.g screen -S rapidlinux

Common screen commands

screen command	Task
Ctrl+a c	Create new window
Ctrl+a k	Kill the current window / session
Ctrl+a w	List all windows
Ctrl+a 0-9	Go to a window numbered 0 9, use Ctrl+a w to see number
Ctrl+a Ctrl+a	Toggle / switch between the current and previous window
Ctrl+a S	Split terminal horizontally into regions and press Ctrl+a c to create new window there
Ctrl+a :resize	Resize region
Ctrl+a :fit	Fit screen size to new terminal size. You can also hit Ctrl+a F for the the same task
Ctrl+a :remove	Remove / delete region. You can also hit Ctrl+a X for the same taks
Ctrl+a tab	Move to next region
Ctrl+a D (Shift-d)	Power detach and logout
Ctrl+a d	Detach but keep shell window open
Ctrl-a Ctrl-\	Quit screen
Ctrl-a ?	Display help screen i.e. display a list of commands

Play with above listed commands. Once you are comfortable with those commands, let's learn one more thing: REMOTE INTERACTION

Scenario: Let's say you SSHed into your client's machine. Your client want to see what commands you are running. You can do that via SCREEN :)

1. SSH into client's machine with your support user ID on client's machine.
e.g #ssh rapidsupport@client.machine

2. Run Screen command with session name
e.g #screen -S rapidsupportSession

3. You have to allow multiple user access in screen session. So, Press Ctrl + a followed by :multiuser on

4. You have to grant permission to client to access your screen session. So, Press Ctrl + a followed by :acladd clientname where clientname is the client's user ID

5. Now client can connect to your screen session using the command syntax #screen -x username/session

e.g #screen -x clientname/rapidsupportSession

6. Now your screen is shared with your client.


Done!!!!

Let's say ur client's machine is behind NAT (i.e client's machine doesn't have public IP ) and you want to provide remote support to your client. Your workstation should have public IP address to support it as ur client.

We can use Reverse SSH to achieve that.

To permit you to access your client's machine through Reverse SSH (Secure Shell protocol), client should execute the following command as root user (superuser) on his machine:

Example:

#ssh -fN -R 5099:localhost:22 rapidsupport@public-ip-address-of-rapidsupport -p 443

where, rapidsupport is an user id on your workstation

If successful, this command will set up an SSH tunnel between client's machine and rapidsupport's workstation, and will display a new command-line prompt on your server.

Note: This method of connecting is called "reverse" SSH because the connection is initiated from client's machine, not from rapidsupport.

Now, rapidsupport can SSH in client's machine using credential of client's machine.

#ssh localhost -p 5099

For more:

http://www.linux.com/archive/feed/56443
http://www.cyberciti.biz/tips/linux-screen-command-howto.html

VLAN : 5 mintue reading to get the core concept of VLAN implementation

VLAN (Virtual LAN) is the logical technique that enables hosts across various LANs to communicate with each other as if they are on same LAN/wire.

VLAN splits the broadcast domain as host on one VLAN can't talk with host on another VLAN without the help of Layer 3 device.

There are two types of the switch port operation mode:

Trunk Mode: Allows multiple VLAN ID to pass through; Usually FastEthernet 0/24 port or GigabitEthernet port for inter-switch link. Multiple switches are interconnected via link connected to the port in Trunk mode.

Access Mode: Allows only one VLAN ID; Hosts are connected to the ports defined as Access mode. By default all ports on the switch are in Access Mode.



Let's see how to define VLAN, add interface/switch ports to VLAN and define TRUNK port

[ In this example we have FinanceDept and HumanResourceDept and we want to separate them using VLAN]

>en
Switch#config term
Switch#hostname Switch1

Switch1-config# vlan 2
Switch1-config-vlan#name HumanResourceDept

Switch1-config-vlan#vlan 3
Switch1-config-vlan#name FinanceDept

Switch1-config-vlan#exit
Switch1-config#exit

Switch1#show vlan
(Find which ports are being used by HumanResourceDept hosts and FinanceDept hosts; say F0/1,F0/2 are being used by HumanResourceDept hosts and F0/3 and F0/4 are being used by FinanceDept hosts)

Switch1#config term
Switch1-config#int F0/1
Switch1-config-if#switchport access vlan 2
Switch1-config-if#int F0/2
Swtich1-config-if#switchport access vlan 2

Switch1-config#int F0/3
Switch1-config-if#switchport access vlan 3
Switch1-config-if#int F0/4
Swtich1-config-if#switchport access vlan 3

Switch1-config-if# [press Ctrl + z]
Switch1#

Now check, if F0/1 and F0/2 are assigned to VLAN 2 , similarly check if F0/3 and F0/4 are assigned to VLAN 3

Switch1#show vlan

Now, hosts belonging to HumanResourceDept connected to Port F0/1 and F0/2 should be able to talk to each other. Perfom ping test.
Similarly do the test with FinanceDept hosts

VERY VERY IMPORTANT CONCEPTS:
>> Hosts on same vlan *must* has same subnet number. For example HumanResourceDept hosts should be under same subnet e.g 192.168.1.0/24 like Host1 IP: 192.168.1.2/24 Host2 IP: 192.168.1.3/24

>> Layer 3 device is required to establish communication between different VLANs


Now, lets define Trunk port on Switch1 so that we can interconnect it to another switch Switch2.

Switch1#config term
Switch1-config#int F0/24
Switch1-config-if#switchport mode trunk

Switch1-config-if# [Press Ctrl + z]

Switch1#show interface trunk

[This will show that F0/24 passes all the VLAN from one switch to another switch. Thus TRUNK mode is only enabled on FastEthernet port and GigabitEthernet port as it requires high bandwidth to pass all VLAN]

Do the same on Switch2

Switch>en
Switch#hostname Switch2

Switch2#config term
Switch2-config#int F0/24
Switch2-config-if#switchport mode trunk

Switch2-config-if# [Press Ctrl + z]

Switch2#show interface trunk


Let's say there is one host of FinanceDept plugged in on port F0/10 of switch2. For the hosts of FinanceDept on switch1 to talk with host on switch2, you have to define VLAN on switch2 and add the desired access port (here in our example: it's port F0/10 on that vlan 3).

Switch2#config term
Switch2-config#int F0/10
Switch2-config-if#switchport access vlan 3

Now, perform ping test between hosts of FinanceDept plugged in to Switch1 and Switch2. [ Friendly reminder: Hosts on same vlan should have same subnet number.]