PD Proxy

PD Proxy

What is PD Proxy?

PD Proxy is simply a VPN software which enables you to visit any site by making your identity anonymous. You can easily open any site which is blocked in your internet connection, I mean by your ISP or if firewall is blocking that site. So, guys with PD proxy, you can change your computer IP address as well as its location easily just some clicks. VPN client is very useful when you use public WiFi connections also.

How to use PD Proxy Premium account:

1. Download PD Proxy premium account Login details from above link.
2. Download PD Proxy from here
3. Now, Enter username and password of PD Proxy premium account.
4. Click on Connect.
5. Enjoy PD Proxy premium account.

PD-Proxy may be a tunneling code which will secure your web association by encrypting all of your connections to the net.

It will remove/unblock content, services and totally different websites that’s ordinarily blocked by your ISP.It will anonymize your association as a result of no one likes to be spied on and caterpillar-tracked. it’ll secure and encipher your association particularly if you employ public access web like WLAN, edifice or cellular phone web. victimisation PD-Proxy makes it not possible for others to spy on you, they can not even see what sites are you’re visiting after you are victimisation PD-Proxy.

No one will tell your real IP address or establish your section.
All the programs put in on your pc are going to be operating mechanically via VPN, that is that the main distinction between VPN and proxy server, requiring code support for proxy association.

Get it and try your own version on

http://www.pdproxy.com/ 

Nagios For Network Management

Nagios

What is Nagios

• “Nagios is an enterprise-class monitoring solutions for hosts, services, and networks released under an Open Source license.”
• It watches hosts and services that you specify, alerting you when things go bad and again when they get better.”
• Developed by Ethan Galstad
• Nagios is quite powerful and flexible, but unfortunately its not very friendly to newbies. 
• Why? Because it takes a lot of work to get it installed and configured properly. 
• That being said, if you stick with it and manage to get it up and running, you’ll never want to be without it.

Introduction

• Nagios: a measurement tool that actively monitors availability of devices and services: 
• Popular: One of the most used open source network monitoring software packages.
• Fast: Uses CGI functionality written in C for faster response and scalability.
• Scalable: Can support up to thousands of devices and services.
• Cool-Looking Web Interface®

Monitoring of…

• Nagios can supervise:

Hosts (Windows, Linux, …) 

• Monitoring of host resources (processor load, disk usage, system logs) on a majority of network operating systems, even Microsoft Windows 
•    Remote monitoring supported through SSH or SSL encrypted tunnels. 

monitoring of network services (SMTP, POP3, HTTP, NNTP, ICMP, SNMP) SNMP Traps
other hardware devices (like temperature sensors,filling level indicator,…)

• In case of emergency send notifications: email, pager, SMS

any user-defined method through plug-in system

What’s good about Nagios?

• It’s conceptually simple
• It handles the load
• It has a web interface
• It’s extensible
• It’s not overly noisy

“Cool-Looking Web Interface®”

Features: 1

• Modular
• Type of availability is largely delegated to plug-ins:

1.           The product's architecture is simple enough that writing new plugins is fairly easy in the language of your choice.
2. There are many, many, many plug-ins available.

Features: Plug-Ins or Modular

• The Nagios package in Ubuntu comes with a number of pre-installed plugins:

 ** apt.cfg    breeze.cfg    dhcp.cfg    disk-smb.cfg    disk.cfg dns.cfg    dummy.cfg    flexlm.cfg    fping.cfg    ftp.cfg   games.cfg    hppjd.cfg http.cfg   ifstatus.cfg   ldap.cfg   load.cfg    mail.cfg    mrtg.cfg mysql.cfg netware.cfg   news.cfg    nt.cfg    ntp.cfg    pgsql.cfg    ping.cfg     procs.cfg radius.cfg    real.cfg  rpc-nfs.cfg    snmp.cfg   ssh.cfg    tcp_udp.cfg telnet.cfg    users.cfg    vsz.cfg **

• There are many more available (e.g.)...

                      http://sourceforge.net/projects/nagiosplugins

Features: 2

• Fast and Scalable
• Compiled, binary CGIs and common plug-ins for faster performance.
• Parallel checking and forking of checks to support large numbers of devices.

1. This has been considerably improved in version 3 of Nagios.
2. Improvement of efficiency is a controversial topic in the Nagios community. 

Features: 3

• Uses “intelligent” checking capabilities.

               * Attempts to distribute the server load of running Nagios (for larger sites) and the load placed on devices being checked. 

• Configuration is done in simple, plain text files, that can contain much detail and are based on templates.
• Nagios reads it's configuration from an entire directory. You decide how to define individual files.

Features: 4

• Topology Aware: To determine dependencies.

 Differentiates between what is down vs. what is not available. This way it avoids running unnecessary checks. This is done using parent-child relationships between devices.

• Notifications: How they are sent is based on combinations of:

Contacts and lists of contacts.

Devices and groups of devices

Services and groups of services

Defined hours by persons or groups.

The state of a service.

Features: 5

• Service state:

• When configuring a service you have the following notification options:

1. d: DOWN: The service is down (not available)
2. u: UNREACHABLE: When the host is not visible
3. r: RECOVERY: (OK) Host is coming back up
4. f: FLAPPING: When a host first starts or stops or it's state is undetermined.
5. n: NONE: Don't send any notifications

How Checks Work

• Parameters: Set in /etc/nagios3/nagios.cfg:

1. Normal checking interval
2. Re-check interval
3. Maximum number of checks.
4. Period for each check

• Services check(s) only happen when a node responds (ping check or “is alive = yes”):

1. Remember a node can be:

              DOWN

              UNREACHABLE

The Concept of “Parents”

1. For example, the parent of a PC connected to the switch mgmt-sw1 would be mgmt-sw1.
2. This allows us to specify the network dependencies that exist between machines, switches, routers, etc.
3. This avoids having Nagios send alarms when a parent does not respond.
4. Note: A node can have multiple parents.

The Idea of Network Viewpoint

• Where you locate your Nagios server will determine your point of view of the network.
• Nagios allows for parallel Nagios boxes that run at other locations on a network.
• Often it makes sense to place your Nagios server nearer the border of your network vs. in the core, or...
• Have someone else run checks for you from an external location as well.

Network Viewpoint

By : mogtaba altyib 
Modification by : Mohammed Bakry PhD

PyQt Designer add an image in PyQt Designer

Add an image in PyQt Designer and make (qrc) file

DNS

Domain Name Service

Hostnames

• IP Addresses are great for computers

                IP address includes information used for routing.

• IP addresses are tough for humans to remember.
• IP addresses are impossible to guess.

              

DNS History

• Advanced Research Projects Agency Network (ARPANET) utilized a central file HOSTS.TXT

            Contains names to addresses mapping

            Maintained by SRI’s NIC (Stanford-Research-Institute:               

            Network-Information-Center)

• Administrators email changes to NIC

             NIC updates HOSTS.TXT periodically

• Administrators FTP (download) HOSTS.TXT

DNS History

• As the system grew, HOSTS.TXT had problems with

           Scalability (traffic and load)

                Name collisions

                Consistency

• n 1984, Paul Mockapetris released the first version (RFCs 882 and 883, superseded by 1034 and 1035 …)
• RFC: Request for Comments
• RFC 882 - Domain names: Concepts and facilities

The “Domain Name System”

• A service that maps between hostnames and IP addresses
• The mechanism by which Internet software translates names to addresses and vice versa
• Mechanism to store and retrieve information in a global data store
• A hierarchical distributed caching database with delegated authority.
• DNS is one of the core Internet Protocols required for operation of the Internet
• Routing and DNS are the most important infrastructure protocols as without them nothing else will work

• Uses port 53

                  UDP for the queries and responses

                  TCP for the zone transfer

• A globally distributed, scalable, reliable database
• Comprised of three components

                   A “name space”

                   Servers making that name space available

                   Resolvers (clients) which query the servers about the name space

DNS as a Database

• Keys to the database are “domain names”

                 www.foo.com, 

• Over 200,000,000 domain names stored
• Each domain name contains one or more attributes

                Known as “resource records”

• Each attribute individually retrievable

Global Distribution

• Data is maintained locally, but retrievable globally

             No single computer has all DNS data

• DNS lookups can be performed by any device
• Remote DNS data is locally cachable to improve performance

Loose Coherency

• Each version of a subset of the database (a zone) has a serial number

               The serial number is incremented on each database change

• Changes to the master copy of the database are propagated to replicas according to timing set           by the zone administrator
• Cached data expires according to timeout set by zone administrator

Scalability

• No limit to the size of the database
• No limit to the number of queries

               Tens of thousands of queries handled easily every second

• Queries distributed among masters, slaves, and caches

Reliability

• Data is replicated

                Data from master is copied to multiple slaves

• Clients can query

               Master server

               Any of the copies at slave servers

• Clients will typically query local caches
• DNS protocols can use either UDP or TCP

               If UDP, DNS protocol handles retransmission, sequencing, etc.

Dynamicity

• Database can be updated dynamically

              Add/delete/modify of any record

              Only master can be dynamically updated

• Modification of the master database triggers replication

DNS Components

2. The name space
3. The servers
4. The resolvers

By : mogtaba altyib 

Modification by : Mohammed Bakry PhD

DHCP

DYNAMIC HOST CONFIGURATION PROTOCOL

HISTORY

• DHCP was created by the Dynamic Host Configuration Working Group of the Internet Engineering Task Force

• ctober 1993: RFC 1531 initially defined DHCP as a standard-track protocol succeeding the Bootstrap Protocol (BOOTP), which is a network protocol used by a network client to obtain an IP address from a configuration server

• October 1997: RFC 2131 released is the current DHCP definition for Internet Protocol version 4 (IPv4) networks

• The extensions of DHCP for IPv6 (DHCPv6) were published as RFC 3315

What is DHCP?

• It is a method for assigning Internet Protocol (IP) addresses permanently or to individual computers in an organization’s network

• DHCP lets a network administrator supervise and distribute IP addresses from a central point and automatically sends a new IP address when a computer is plugged into a different place in the network

DHCP

• DHCP a network service that enables clients to obtain network settings (IP Address, Subnet Mask, Default Gateway, DNS Server, Hostname and Domain) automatically from a central server
• The DHCP client sends a broadcast request to find the DHCP server and the DHCP server in the subnet responds with an IP address (and other common network parameters) from a pool of IP addresses
• The IP address can be bound to the MAC address of the client

                 Dynamically update DNS servers

                 Divide hosts into classes, based on many criteria

• When you configure Windows to “Obtain an address automatically,” DHCP is the service providing that address

• Server offers IP address and network parameters for a limited time (called a lease)
• In practice, leases may vary from 30 minutes to a week or so
• Short lease:

                 Clients get updated parameters quickly

                 Essential if you have more clients than addresses

                 Requires more processing power on the server

• Long Lease:

                  More reliable (clients may continue to operate for a week after DHCP server fails)

                  But takes longer for all clients to get new settings if they change.

Motivation for DHCP

• Configuration parameters for network hosts

1. IP address
2. Router
3. Subnet Mask
4. Others.

Why is DHCP Important?

• Important when it comes to adding a machine to a network
• When computer requests an address, the administrator would have to manually configure the machine

                     Mistakes are easily made

                     Causes difficulty for both administrator as well as neighbors on the network

• DHCP solves all the hassle of manually adding a machine to a network

How does DHCP work?

• When a client needs to start up TCP/IP operations, it broadcasts a request for address information
• The DHCP server will not reallocate the address during the lease period and will attempt to return the same address every time the client requests an address

• The client can extend its lease or send a message to the server before the lease expires it that it no longer needs the address so it can be released and assigned to another client on the network 

Advantages of DHCP

• DHCP minimizes the administrative burden

•  By using DHCP there is no chance to conflict IP address

• By using DHCP relay agent you provide IP address to another network

Disadvantages of DHCP

• When DHCP server is unavailable, client is unable to access enterprises network

• Your machine name does not change when you get a new IP address 

Security problem

• DHCP is an unauthenticated protocol
• When connecting to a network, the user is not required to provide credentials in order to obtain a lease
• Malicious users with physical access to the DHCP-enabled network can instigate a denial-of-service attack on DHCP servers by requesting many leases from the server, thereby depleting the number of leases that are available to other DHCP clients

Limitations 

• Some machines on your network need to be at fixed addresses, for example servers and routers
• You need to be able to assign a machine to run the DHCP server continually as it must be available at all times when clients need IP access 

DHCP operations

DHCPDISCOVER — from client

client has no address, asking for a new one

DHCPOFFER — from server

Offer of address and other parameters

DHCPREQUEST — from client

Client asks if it can use the offered address and parameters

DHCPACK — from server

Server says “yes, go ahead, this address and these parameters are yours; the lease starts now.”

DHCPNAK — from server

client has no address, asking for a new one

DHCPDECLINE — from client

Client has detected another machine is using the offered address, and tells the server about this problem

DHCPRELEASE — from client

Server expires the lease immediately

DHCPINFORM — from client

Client already has an IP address, but wants other network settings from the server

By : mogtaba altyib 
Modification by : Mohammed Bakry PhD

Proxy server

Proxy server

•  A proxy server is a sever that acts as an intermediary between a workstation user and the internet so that the enterprise can ensure security, administrative control, and caching service.

•  By using the proxy server you can hide, conceal and make your network id anonymous by hiding your IP address.

•  A proxy is server that sits between a client application, such as Web browser, and a real server.

Purpose of proxy server

• To keep machines behind it anonymous(mainly for security)
• o improve performance:

                Act as cache server

                Bandwidth control 

• Filter requests

               Prevent access to some web sites

               Prevent access to some protocols

Improve performance

• Caching

           Reduce latency

                Reduce network traffic.

• Bandwidth control

                 Policy-based bandwidth limits

                 Deny by content type

What do you need for proxy installation?

• Proxy software
• Server
• At least 2 network cards
• Direct internet connection(public IP address)
• witch/Hub(elective)
• Private IP address

How a proxy work?

1

2

3

4

5

Popular hardware & software proxies

Main Proxy Functions

1. Caching
2. Firewall
3. Filtering
4. Logging

Web Cache Proxy

• Our concern is not with browser cache!
• Store frequently used pages at proxy rather than request the server to find or create again

• Why?

• Reduce latency: faster to get from proxy & so makes the server seem more responsive
• Reduce traffic: reduces traffic to actual server

Proxy Caches

• Proxy cache serves hundreds/thousands of users
• Corporate and intranets often use
• Most popular requests are generated only once
• Proxy cache hit rates often hit 50%

How Does a Web Cache Work?

• Set of rules in either or both

               Proxy admin 

               HTTP header

• Use cache copy if it is fresh

              Within date constraint

              Used recently and modified date is not recent

By : mogtaba altyib 
Modification by : Mohammed Bakry PhD

Linux Network Configuration and Troubleshooting Commands

Linux Network Configuration and Troubleshooting Commands

NIC: Network Interface Card

Use “ipconfig” command to determine IP address, interface devices, and change NIC configuration

Determining NIC IP Address

[root@tmp]# ifconfig -a

eth0 Link encap:Ethernet HWaddr 00:08:C7:10:74:A8

BROADCAST MULTICAST MTU:1500 Metric:1

RX packets:0 errors:0 dropped:0 overruns:0 frame:0

TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:100

RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

Interrupt:11 Base address:0x1820

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

UP LOOPBACK RUNNING MTU:16436 Metric:1

RX packets:787 errors:0 dropped:0 overruns:0 frame:0

TX packets:787 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:82644 (80.7 Kb) TX bytes:82644 (80.7 Kb)

Changing IP Address

We could give this eth0 interface an IP address using the ifconfig command.

[root@tmp]# ifconfig eth0 10.0.0.1 netmask 255.255.255.0 up

The "up" at the end of the command activates the interface.

To make this permanent each time boot up by add this command in /etc/rc.local file which is run at the end of every reboot.

Permanent IP configuration

—  Fedora Linux also makes life a little easier with interface configuration files located in the /etc/sysconfig/network-scripts directory.

—  Interface eth0 has a file called ifcfg-eth0, eth1 uses ifcfg-eth1, and so on.

—  Admin can place your IP address information in these files

File formats for network-scripts

root@network-scripts]# less ifcfg-eth0

DEVICE=eth0

IPADDR=192.168.1.100

NETMASK=255.255.255.0

BOOTPROTO=static

ONBOOT=yes

#

# The following settings are optional

#

BROADCAST=192.168.1.255

NETWORK=192.168.1.0

[root@network-scripts]#

Activate config change

—  After change the values in the configuration files for the NIC you have to deactivate and activate it for the modifications to take effect.

—   The ifdown and ifup commands can be used to do this:

[root@network-scripts]# ifdown eth0

[root@network-scripts]# ifup eth0

1.       ifconfig

—  ifconfig (interface configurator) command is use to

¡   initialize an interface,

¡   assign IP Address to interface

¡   and enable  or disable interface on demand.

—  With this command you can view

¡   IP Address 

¡  and Hardware / MAC address assign to interface

¡  and also MTU (Maximum transmission unit) size.

 ifconfig with interface (eth0) command only shows specific interface details like IP Address, MAC Address etc.

—  with -a options will display all available interface details if it is disable also.

Assigning IP Address and Gateway

—  Assigning an IP Address and Gateway to interface on the fly.

—  The setting will be removed in case of system reboot.

Enable or Disable Specific Interface

 To enable or disable specific Interface, we use example command as follows.

—  

Setting MTU Size

By default MTU size is 1500. We can set required MTU size with below command. Replace XXXX with size.

Set Interface in Promiscuous mode

Network interface only received packets belongs to that particular NIC. If you put interface in promiscuous mode it will received all the packets. This is very useful to capture packets and analyse later. For this you may require super user access.

how do I Configure Static IP Address Internet Protocol (IPv4)?

—  Assign Static IP Address to eth0 interface editing configuration file  /etc/network/interfaces to make permanent changes as shown below.

Next, restart network services after entering all the details using the following command.

  How to Remove an IP Address

—  The following command will remove an assigned IP address from the given interface (eth1).

2.       PING Command

—  PING (Packet INternet Groper) command is the best way to test connectivity between two nodes.

—  Whether it is Local Area Network (LAN) or Wide Area Network (WAN).

—  Ping use ICMP (Internet Control Message Protocol) to communicate to other devices. You can ping host

 name of ip address using below command.

—  In Linux ping command keep executing until you interrupt.

—  Ping with -c option exit after N number of request (success or error respond).

3.       TRACEROUTE Command

—  traceroute is a network troubleshooting utility which shows number of hops taken to reach destination

—   also determine packets travelling path.

—  Below we are tracing route to global DNS server IP Address and able to reach destination also shows path of that packet is travelling.

4.       NETSTAT Command

—  Netstat (Network Statistic) command display connection info, routing table information etc.

—  To displays routing table information use option as -r.

Listing all ports (both TCP and UDP) using netstat -a option.

Listing only TCP (Transmission Control Protocol) port connections using netstat -at.

Listing all active listening ports connections with netstat -l.

5.       DIG Command

—  Dig (domain information groper ) is a tool for querying DNS nameservers for information about host addresses, mail exchanges, nameservers, and related information.

—   This command mainly use to troubleshoot DNS related query.

6.       NSLOOKUP Command

—  nslookup command also use to find out DNS related query. The following examples shows A Record (IP Address) of tecmint.com.

7.       ROUTE Command

—  route command also shows and manipulate ip routing table.

—   To see default routing table in Linux, type the following command.

Adding, deleting routes and default Gateway with following commands.

8.       HOST Command

—  host command to find name to IP or IP to name in IPv4 or IPv6 and also query DNS records.

9.       ETHTOOL Command

.   ethtool is a replacement of mii-tool. It is to view, setting speed and duplex of your Network Interface Card(NIC).

.   You can set duplex permanently in /etc/sysconfig/network-scripts/ifcfg-eth0 with ETHTOOL_OPTSvariable.

By : mogtaba altyib 
Modification by : Mohammed Bakry PhD