Some of my drawings on batting mastero sachin tendulkar ..hope you like it :)

Some more Clicks !!...:)

Ranjan's Photography...

This diwali i thought of a little gift for myself ..a nice DSLR camera whcih will help me to improve my creativity and photography skills and fortunately i found a "Canon EOS 1000D / Rebel XS "in a shop near my home and without any second thought i bought it.

Photography is wonderful and is my new found hobby. This a small collection of various photos I have ...hope you guys will like it ..:)

ಕನ್ನಡ ರಾಜ್ಯೋತ್ಸವದ ಹಾರ್ದಿಕ ಶುಭಾಶಯಗಳು !!.

ಎಲ್ಲಾದರು ಇರು ಎಂತಾದರು ಇರು ||೨||

ಎಂದೆಂದಿಗೂ ನೀ ಕನ್ನಡವಾಗಿರು
ಕನ್ನಡವೇ ಸತ್ಯ, ಕನ್ನಡವೇ ನಿತ್ಯ

ಕನ್ನಡ ಗೋವಿನ ಓ ಮುದ್ದಿನ ಕರು ||೨||
ಕನ್ನಡತನ ಒಂದಿದ್ದರೆ, ಅಮ್ಮಗೆ ಕಲ್ಪತರು
ಕನ್ನಡವೇ ಸತ್ಯ, ಕನ್ನಡವೇ ನಿತ್ಯ
ಎಲ್ಲಾದರು ಇರು ಎಂತಾದರು ಇರು
ಎಂದೆಂದಿಗೂ ನೀ ಕನ್ನಡವಾಗಿರು

ನೀ ಮೆಟ್ಟುವ ನೆಲ, ಅದೆ ಕರ್ನಾಟಕ
ನೀನೇರುವ ಮಲೆ ಸಹ್ಯಾದ್ರಿ
ನೀ ಮೆಟ್ಟುವ ನೆಲ, ಅದೆ ಕರ್ನಾಟಕ
ನೀನೇರುವ ಮಲೆ ಸಹ್ಯಾದ್ರಿ

ನೀ ಮುಟ್ಟುವ ಮರ ಶ್ರೀಗಂಧದ ಮರ ||೨||
ನೀ ಕುಡಿಯುವ ನೀರ್ ಕಾವೇರಿ

ಪಂಪನ ಓದುವ ನಿನ್ನಾ ನಾಲೆಗೆ
ಕನ್ನಡವೇ ಸತ್ಯ
ಕುಮಾರವ್ಯಾಸನ ಆಲಿಪ ಕಿವಿಯದು
ಕನ್ನಡವೇ ನಿತ್ಯ

ಎಲ್ಲಾದರು ಇರು ಎಂತಾದರು ಇರು
ಎಂದೆಂದಿಗೂ ನೀ ಕನ್ನಡವಾಗಿರು

ಹರಿಹರ ರಾಘವರಿಗೆ ಎರಗುವ ಮನ
ಹಾಳಾಗಿಹ ಹಂಪೆಗೆ ಕೊರಗುವ ಮನ
ಹರಿಹರ ರಾಘವರಿಗೆ ಎರಗುವ ಮನ
ಹಾಳಾಗಿಹ ಹಂಪೆಗೆ ಕೊರಗುವ ಮನ

ಬೆಳ್ಗೊಳ ಬೇಲೂರ್‍ಗಳ ನೆನೆಯುವ ಮನ

ಮಲೆನಾಡಿಗೆ ಹೊಂಪುಳಿ ಹೋಗುವ ಮನ
ಕಾಜಾಣಕೆ ಗಿಳಿ, ಕೋಗಿಲೆ ಇಂಪಿಗೆ
ಮಲ್ಲಿಗೆ ಸಂಪಿಗೆ ಕೇದಗೆ ಸೊಂಪಿಗೆ
ಕಾಜಾಣಕೆ ಗಿಳಿ, ಕೋಗಿಲೆ ಇಂಪಿಗೆ
ಮಲ್ಲಿಗೆ ಸಂಪಿಗೆ ಕೇದಗೆ ಸೊಂಪಿಗೆ

ಮಾವಿನ ಹೊಂಗೆಯ ತಳಿರಿನ ತಂಪಿಗೆ

ರೋಮಾಂಚನಗೊಳ್ಳುವ ಮನ
ಕನ್ನಡವೇ ಸತ್ಯ, ಕನ್ನಡವೇ ನಿತ್ಯ
ಎಲ್ಲಾದರು ಇರು ಎಂತಾದರು ಇರು
ಎಂದೆಂದಿಗು ನೀ ಕನ್ನಡವಾಗಿರು

ಎಲ್ಲಿದ್ದರೆ ಏನ್ ಎಂತಿದ್ದರೆ ಏನ್
ಎಲ್ಲಿದ್ದರೆ ಏನ್ ಎಂತಿದ್ದರೆ ಏನ್

ಎಂದೆಂದಿಗು ತಾನ್ ಕನ್ನಡವೇ ಸತ್ಯ ಕನ್ನಡವೇ ನಿತ್ಯ
ಅನ್ಯವೆನಲದೆ ಮಿಥ್ಯ

ALG - Application Level Gateway

An Application Layer Gateway (ALG) is a software component that is designed to manage specific protocols such as Session Initiation Protocol (SIP) or File Transfer Protocol (FTP)

The ALG intercepts and analyzes the specified traffic, allocates resources, and defines dynamic policies to permit the traffic to pass securely through the ALG.

Application level Gateway, as the name suggests, operates in the Application layer of the OSI model and actively inspects the contents of packets that are passed through to the gateway. Let's go ahead into the details of its functioning to understand this technology better.

The Application Level Gateway acts as a proxy for applications, performing all data exchanges with the remote system in their behalf. This can render a computer behind the firewall all but invisible to the remote system.

It can allow or disallow traffic according to very specific rules, for instance permitting some commands to a server but not others, limiting file access to certain types, varying rules according to authenticated users and so forth. This type of firewall may also perform very detailed logging of traffic and monitoring of events on the host system, and can often be instructed to sound alarms or notify an operator under defined conditions.

Application-level gateways are generally regarded as the most secure type of firewall. They certainly have the most sophisticated capabilities.

A disadvantage is that setup may be very complex, requiring detailed attention to the individual applications that use the gateway.

An application-level gateway acts as a intermediate system between the Internet and the application server that understands the relevant application protocol. This application-level gateway's system appears to the outside world as the end point application server, but in reality, the gateway interprets each incoming request, reduces the request to the application server's own internal lexicon, then builds a new request from scratch discards and prevents any malicious, malformed content from getting through. The gateway then sends a new request to the actual application server and processes the servers reply in the same fashion.

An application-level gateway intercepts the incoming and outgoing packets, runs a proxy to copy and forward information across the gateway, and functions as a proxy server, thereby preventing any direct connection between a trusted server or client and an untrusted host.

Functions of an ALG can be defined as:

Allow client applications to use dynamic TCP/ UDP ports to communicate with the known ports used by the server applications, even though a firewall configuration may allow only a limited number of known ports. In the absence of an ALG, either the ports would get blocked or the network administrator would need to explicitly open up a large number of ports in the firewall - rendering the network vulnerable to attacks on those ports.

Convert the network layer address information found inside an application payload between the addresses acceptable by the hosts on either side of the firewall/NAT.

Recognize application-specific commands and offering granular security controls over them

Synchronize between multiple streams/sessions of data between two hosts exchanging data.

Deep packet-inspection of all the packets over a given network

Two types of Proxies used by application-level gateways are:

Application-specific Proxies

Application-level Filtering

Application-specific Proxies. Application-specific proxies accept only packets that are generated by services they are designed to copy, forward, and filter. There is a drawback here that is if a network relies only on an application-level gateway, incoming and outgoing packets cannot access services for which there is not a proxy. For example, if an application-level gateway runs a Telnet proxy, only packets generated by this service could pass through the firewall. All other services would be blocked.

Application-level Filtering. An application-level gateway runs proxies that examines and filters individual packets. This is achieved by checking each packet that passes through the gateway, verifying the contents of the packet up through the application layer of the OSI model. These proxies can filter particular kinds of commands or information in the application protocols the proxies are designed to copy, forward, and filter.

TCP Explained.

Always on Time !!..The Transmission control protocol (TCP) Provides applications with reliable ,connection-oriented service and provides full logical path between two hosts on disparate networks .

This article is an attempt to detail the different fields available in the TCP segment .

Source and Destination port :Its a 16 bit field that specifies the source and destination applications for the encapsulated data.

RFC 1700 describes all the ports number in common and not so-common use (http://www.ietf.org/rfc/rfc1700.txt).

A port number for an application ,which is combined with an ip address of the applications where host resides in , is called a socket .
Sequence number : Its a 32 bit identifier which identifies where the encapsulated data is fits within a data stream .
If the sequence number of a segment is 1 and the segments contains 512 octets ..the next segment should have sequence number of 1+512=513.
Acknowledgment number :Its a 32 bit field which tells what would be the sequence number the source expects to receive from destination.
If a hosts receives a acknowledgment number that doesn't match the next sequence number it intends to send , it concludes that packets earlier sent has not reach the destination and it will re-transmits the same.

Header Length :Its a data offset and a four bit field indicates the length of the header in 32-bit words and indicates the beginning of the data.
Reserved Field :Its of six bites ..which are always set to zero.

Flags :They are six 1-bit flags that used for data flow and control .
URG -Urgent
ACK-Acknowledgment
PSH-Push
RST-Reset
SYN-Synchronize
FIN-Final

Window Size: 16 bit field used for flow control .It specifies the number of octets,starting with the octet in indicated by acknowledgment number, that the sender of the segment will accept from its peer.
It specifies how much data it can handle or process at a time .

Checksum: Its a 16 bit field covering both the header and the encapsulated data,allowing error detection.
Urgent pointer :Its again a 16 bit field ..its used only when the URG Flag is set..urgent pointer added to the sequence number indicating the end of the urgent data.

Options :Optional field .One good example is maximum segment size ..which indicates what will be the maximum segment size sender is willing to accept .

The remainder of the field is padded with zeroes to ensure that the header length is multiple of 32 octets .

Here below is an example of TCP packet capture details using Wireshark

A sneak peak in to the IP Packet.

Though Most of us know about the IP packet..here is an attempt to explain the IP packet detailing each and every field it has.

Ok..now let's sneak in to a IP packet ..



Version:Version identifies which version of the IP (Either IPv4 or IPV6) This packet belongs to.And this is a four bit field usually set to binary 0100.

Header Length:Header length is also a 4 bit field in an IP Packet and as the name implies its tells about the length of the IP header.
The minimum length of a IP header is 20 octets and can scale up to 24 octets.
TOS (Type of Service):Its a 8 bit field which can be broken down in to two parts .a)precedence :Which talks about the priority Very urgent,urgent or normal delivery of the packet and b)TOS :and this deciding on the priority of delivery will be based on throughput,delay,reliability and monetary cost factors.

And yep!!.this precedence will be used in QoS (Quality of Service) applications.

Total Length: It talks about the total length of the IP Packet including the header in octets ranging from 16 to 65,535 octets . This field consist of 16 bit.

Identifier:Imagine you are sending a 5000 byte packets in the network and it encounters a data link whose MTU is set 1500 bytes and that means that link can handle only 1500 bytes at a time. in that case the entire packet will be fragmented in to the chuncks of not more than 1500 bytes and then router marks each fragment with the same number in the identifier field so that a receiving device can identify the fragments and that go together in the end . This field consists of 16 bits .

Flags: Its a three bit field ..where first bit will be unused . second one is don't fragment(DF) bit .When this bit is set to on (1), the device which handling the packet cann't fragment the incoming packet .

If the incoming packet is of size which is larger than it can handle and if its not allowed to fragment than it will drop the packet and sends an error message to the source of the packet and this DF option will be set to determine the MTU on a network .

The third bit is MF(More fragments) bit..when a device fragments a packet , it sets MF bit to one and on the last packet where there is no more packets need to be fragmented it will set the MF bit to zero .

Fragment Offset :Its specifies offsets and responsible for fragments packets to re-assembled in the correct order in the end .

TTL(Time To Leave):You know it ..when a packet starts it journey towards its destination in a network ...as it passes through each hops (routers) the initially set value of TTL is decremented by one so that it prevents lost packets from wandering endlessly through an inter network and when the TTL value reaches zero packet will be discarded and the error message will be sent to the source.

Protocol:It talks about which transport layer protocol like this packet is destined for .( Example :1 is for ICMP.6 for TCP and 17 for UDP).

Header checksum :Its used for error-correction and its not used for encapsulated data.Its a 16 bit field field where the checksum will calculated at the source and once its received at the destination the checksum will be again calculated and if the checksums are exactly matching ( all one's) than it proves that packet is recieved without any errors and received intact .

Source and Destination Address: We all know abt this ! ..its 32 bit IP address . Identifies the source and destination.

Options : Its Optional!!..only used when it need contains any source generated information or for other routers to enter information like timestamp and strict source routing where its strictly defined how the packets should be routed via which routers interfaces .

Padding ensures that header ends on a 32 bit boundaryby adding extra zeroes after the option field until a multiple of 32 is reached .

Wireshark capture of an IP packet as below;