How to create LVM

How to create LVM partition in linux, LVM is a logical volume manager it manages disk drivers and similar mass-storage devices.

The commands used in LVM are,

Physical Volume = pv
Volume Group = vg
Logical Volume = lv

Step 1: Find the disk volume using fdisk -l, ex: /dev/sdb

Step 2: Create Phycial volume

# pvcreate /dev/sdb

Step 3: Create Voume Group

# vgcreate vg0 /dev/sdb

vg0: Volume group name can be any name

Step 4: Create Logical Volume

# lvcreate -l 100%FREE -n lv0 vg0

100%FREE: Utilizing 100% of the disk space

lv0: Logical Volume name can be any name

Step 5: Format the disk with ext3 or ext4 filesystem

#mkfs.ext3 /dev/vg0/lv0

#mkfs.ext4 /dev/vg0/lv0 (for RHEL 6)

Step 6: Add fstab entry for permanent mount

#vi /etc/fstab

/dev/vg0/lv0 /data ext3 default 0 0

/data: Directory

ext3: File system type

Step 7: mount the disk

#mount /dev/vg0/lv0 /data

#mount -a

How to change hostname in linux without reboot

We can change the hostname (server name) in linux without rebooting the linux box.

Step 1: edit /etc/hosts file and set the hostname
#vi /etc/hosts
10.0.0.4 digitalinux.digitalinux.com digitalinux

10.0.0.4: Server Ip address
digitalinux: Server name
digitalinux.com: domain name
digitalinux.digitalinux.com: FQDN

Step 2: edit /etc/sysconfig/network and change the hostname
#vi /etc/sysconfig/network
HOSTNAME=digitalinux.digitalinux.com

Change the hostname as above

Step 3: Change hostname without reboot
# hostname digitalinux.digitalinux.com

3D Desktop

Available Packages: Compiz, Beryl

Compiz:

By installing the package compiz and enabling the Desktop Effects in the system menu.
rpm –ivh compiz-0.0.13-0.36.20060817git.el5.i386.rpm --aid
System -> Preferences -> Desktop Effects
Now By accessing the following keys to get the 3D Desktop:
Ctrl + Alt + Arrow keys, & Using Mouse.

Beryl:

Copy the Beryl packages in to a directory /var/ftp/pub/Beryl
Adding an entry in the
/etc/yum.repo.d/<server1>.repo
vim /etc/yum.repo.d/server1.repo
[Beryl]
name=server1 SERVER repository
baseurl=file:///var/ftp/pub/Beryl
gpgcheck=0
createrepo -v /var/ftp/pub/Beryl
yum install –y beryl*

For client machines
add an entry in the
/etc/yum.repos.d/<client>.repo
vim /etc/yum.repo.d/client.repo
[Beryl]
name=Client Server Repository
baseurl=ftp://192.168.0.254/pub/Beryl
gpgcheck=0
yum install –y beryl*

Starting the beryl settings

Applications -> System Tools -> select Beryl Manager
Right click on the Beryl Manager icon in the time toolbar and select Beryl Settings Manager, Now the options are Displayed, change the settings as you wish.
Now By accessing the following keys to get the 3D Desktop:
Ctrl + Alt + Arrow keys, & Using Mouse

WEB PROXY

-->

PACKAGES NEEDED FOR CONFIGURATION

squid

IF THE PACKAGES ARE NOT AVAILABLE INSTALL THROUGH YUM INSTALLER
yum install squid

THE MAIN CONFIGURATION CAN BE EDITED AS FOLLOWS
vim /etc/squid/squid.conf
http_port 3128

SEARCH FOR THE WORD /OUR_NETWORKS, THEN ENTER THE FOLLOWING LINES

acl example src 192.168.0.0/255.255.255.0
http_access allow example

--> You can now refer to this network as "example" elsewhere in the configuration file.
--> src means that the IP specified is the source Ip(s) for this acl

DAEMON SERVICES SHOULD BE STARTED AND ENABLED AFTER REBOOT
service squid start/restart/reload
chkconfig squid on

--> To set the proxy settings in Firefox, navigate to
Edit->Preferences. In the General settings, click on the Connection Settings... button. Click the Manual proxy configuration radio button. Add localhost in the HTTP Proxy: box, and 3128 in the Port: box. Click OK to accept the changes.
--> Try accessing a web page somewhere.

How to Install VMWare on Linux

-->

INSTALL VMWARE ON LINUX
1.mount 192.168.0.154:/dumps /media
2.cd /media/VMWARE
3.rpm -ivh VMware-server-1.0.1-29996.i386.rpm
4.yum install gcc kernel-devel xinetd -y
5.vmware-config.pl
6.cat vmware-server.key

TO EXTRACT WINDOWS IMAGE
1.scp nanju@192.168.0.154:/home/nanju/suma/raj.tar.bz2 .
2.tar jxvf raj.tar.bz2 -C /var/lib/vmware

CONFIGURE SAMBA SERVER

CONFIGURE SAMBA SERVER
Step 1.mkdir /samba
Step 2.chmod a+w /samba
Step 3.yum install samba -y
Step 4.vim /etc/samba/smb.conf
[public]
comment = Only users
path = /samba
public = yes
browseable=yes
writable = yes
printable = no
write list = +staff
Step 5.service smb restart

OPTIONS THAT CAN BE GIVEN IN FILE
Step 1.If browseable=yes ->we CAN see the shared dir
If browseable=no -> we CANNOT see the shared dir
Step 2.If public=yes ->Allows anonymous Login
If public=no ->Stops anonymous Login
Step 3.writable = no ->uploading is denied for BOTH the users.
writable = yes ->uploading is allowed for BOTH the users
Step 4
a. writable =no + ->Allows only u1 to upload files, but
b. write list =u1 both writable=no and writelist=u1 shuld b enabled
Step 5.hosts allow=127. 192.168.0.20 ->Allow only 192.168.0.20 ip to access share, other ips are denied

CLIENT COMMANDS
Step 1.smbclient -L //192.168.0.48/share ->List directories shared
Step 2. smbclient //192.168.0.48/share ->Anonymous Login
get <file>
put <file>
Step 3a. To generat passwd to allow for non-anonymous login
1. smbpasswd -a u1
2. service smb restart
Step 3b. smbclient //192.168.0.48/share -U u1 ->Non Anonymous Login
get <file>
put <file>

PORT MONITORING TOOLS

PORT MONITORING TOOLS

SHOWS all applications running in local machine:

1. pkg:-net-tools-1.60-73 -> installed by default
netstat -tulpn |grep <service>
t->tcp u->udp l->listening p->pid n->numericip
2. pkg:-nmap-4.11-1.1 -> installed by default
nmap <ip.address> |grep <service>

SHOWS all applications running in entire network:

1. yum install wireshark
Applications-->Internet-->wireshark-->capture
2. pkg:-tcpdump-3.9.4-11.el5 -> installed by default
tcpdump -c <ip.address> |grep <service>

TCP WRAPPERS

Services which contain libwrap module can use hosts.deny to control Access
ldd /usr/sbin/vsftpd |grep libwrap
ldd /usr/sbin/sendmail |grep libwrap
ldd /usr/sbin/sshd |grep libwrap

To Restrict a host/network to control access to a Service.

1. Using Hostname/Domainname
vim /etc/hosts.deny
-> vsftpd *.example.com ->All hosts in example.com denied to access ftp
-> vsftpd server.example.com ->Host server in example.com denied to access

2. Using Ipaddress/Network
vim /etc/hosts.deny
-> vsftpd 192.168.1.0/255.255.255.0 ->All hosts in 1.0 N/W denied.
-> vsftpd 192.168.1.4 ->Host 1.4 denied.

3. To Deny all Except few.
vim /etc/hosts.deny
-> sshd:ALL EXCEPT matrix.com ->Any domain other than matrix.com are denied the Access to ssh.

4. To Allow all Except few.
vim /etc/hosts.allow
-> ALL *.example.com EXCEPT *.matrix.com ->Any domain other than matrix.com are Allowed to Access.

Both entries allow/deny can be given in either hosts.allow or hosts.deny file

SSH Configuration

SSH Configuration

--> Pkg -openssh
Daemon -sshd
Portnum -22
Files -/etc/ssh/sshd_config
.ssh/*
---> vim /etc/ssh/sshd_config

1. line 13 -> change port num.
Port 53
service sshd restart
client connecting to your machine should connect giving like this
ssh -p 53 <server ip> ,Only then it connects.

2. line 37 -> Allow/stop user to ssh
AllowUsers u1
DenyUsers u2
service sshd restart
This stops a client to connect as u2 and can connect as only u1 user.

3. line 37 -> Allow/stop user to ssh
AllowGroups asia
DenyGroups america
service sshd restart
This stops a client to connect as any members of america, and can connect
as any member os america.

4. line 38 -> Login grace time.
LoginGraceTime 1m
service sshd restart
Once you connect to sshserver, you haf to provide passsword within a min,
or connection fails.

5. line 39 -> Root login allowed/not-allowed
PermitRootLogin no
service sshd restart
This stops a client to ssh as root user,anb can connect as normal user only

6. line 41 -> Password prompts
MaxAuthTries 1
service sshd restart
Password is prompted only twice within which he has to give right password
to authenticate.

7. line 96 -> Stop Gui Access
X11Forwarding no
service sshd restart
Thou the client connects to your server using ssh -X <server.ip>, they
wont be able to connect to GUI of Server

8. Generating Public/Private key
--> To generate the key ->Generates id_dsa,id_dsa.pub files under .ssh dir
ssh-keygen -t dsa
--> To copy key to client machine ->copies id_dsa to .ssh of clients machine
ssh-copy-id -i /root/.ssh/id_dsa <clients.ip>

Syslog Server

Configure Syslog server
Step 1.vim /etc/sysconfig/syslog
sysLOGD_OPTIONS = "r"
Step 2.service syslog restart
Step 3. tailf /var/log/message

To redirect all clients log message to file called remote
Step 1.vim /etc/syslog.conf
Step 2.*.* /var/log/remote

Clients to redirect there logs to syslogserver(192.168.0.45)

Step 1.vim /etc/syslog.conf

*.* @192.168.0.45

Step 2.service syslog restart

Digital Linux

How to create LVM

How to change hostname in linux without reboot

3D Desktop

WEB PROXY

How to Install VMWare on Linux

CONFIGURE SAMBA SERVER

PORT MONITORING TOOLS

TCP WRAPPERS

SSH Configuration

Syslog Server

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