The Point To Point Protocol (PPP)

Protocols are a part of our everyday existence. We follow protocols in everything we do. Put simply, protocols are rules for doing things. You may say ‘I walk the wild side and so rules or protocols apply to me’, well then you are sadly mistaken. You have `set’ yourself the `rule’ that you will not follow any rules. Hence not following any rules becomes your rule and hence your protocol.

So much for protocols. Lets get to the point, you are here to know and understand PPP, which stands for the Point to Point Protocol. As of today, the most common means of surfing the Internet is via a ‘dial-up service’. Remember we said the `most common means’. People using other services like radio links or leased lines belong to the `chosen’ community and don’t have to worry about these protocols. The Ethernet approach to the ‘Net necessitates the use of Ethernet based protocols so check out our tutorial on them if you are interested. Continue reading

SNMP: The Simple Network Management Protocol

When we were young, we wanted to become a pilot, astronaut or a fire engine driver.
-Our mothers would laugh at us.
When we were in our pre-teens, we wanted to become programmers.
-Our fathers would laugh at us.
When we became programmers, we wanted to become network administrators.
– The world (our girlfriends included) would laugh at us.

The above is not a figment of our imagination but facts relating to our daily life. When we started off as programmers we proved our fathers wrong. Sorry, we could not do the same regarding our mothers. This left us with the world and our girlfriends to deal with. It took us some time to devise ways to prove them wrong. But before we let you into our secret of how to do it, lets try and justify their laughs.

Network administrators of yore were perfect nerds, living in ivory towers(actually dingy low-lit rooms , disconnected from the world). In short, they were people to be avoided, basically belonging to class called social rejects. The rationale behind this was very simple. Network administrators had no control over their networks. Continue reading

LDAP – The Lightweight Directory Service

“To err is human but to really screw up things need a computer.”
-Old jungle saying

As all doomsayers had been predicting, computers have taken control of our lives. Computers touch every aspect of our daily lives. We need computers for carry out simple tasks or for performing equally complicated ‘superhuman’ (or inhuman) tasks. All these information is stored in the computer in the form of files. These files are stored in different directory which may be stored on different drives. The first few days of possessing a computer can be termed as a `honeymoon’ period. During this period we seem to remember all the files names along with their storage slots (technically called sub-directories). But with the passage of time the disks start filling up and nobody seems to remember `what is stored where’. To add insult to injury the system boots up only to tell us `missing file so-and-so system halted’ or some equally esoteric message. So what do you do in such a situation. Continue reading

Basic Encoding Rules

Brrr….Its Hot : –

The compilation rules for converting data-types into bits and bytes is called the transfer syntax.Basic Encoding Rules or BER is the transfer syntax for SNMP and LDAP. BER and ASN.1 were designed by the same people (not network administrators alone) and hence go hand in hand. This fact makes life simpler on this planet. But how does BER manage to do all this, after all it has to take case of so many data-types, and it is used to write hundreds of protocols. It is indeed mind boggling. To know more about BER lets get cracking Fortunately we will only discuss BER in the context of ASN.1 implementation of SNMP and LDAP. Continue reading

BER – LDAP

Turn on the heater… It’s chilling… BERRRR..

We love BER for two simple reasons.

  1. It is very simple (that’s why we understand it)
  2. Being a standard ‘language’ used to code protocols.

Once you understand BER, understanding the overlying protocol becomes very easy. (Hence this tutorial) In this chapter we will look at the ‘BER implementation for LDAP’. The rules of the game remain the same. The first two bits of the BER identifier define the class, the next bit defines the type of variable, whereas the remaining bits define the actual datatype. Let’s look at each of them. In this case we will use a `bottoms-up’ approach (don’t get the glasses please) We only meant that let do the last bits first. Continue reading

BER SNMP

Still reeling under the cold…..BERRRR…..

As already explained the last five bits in case of the BER identifier are used to denote the numeric tag of the object. Since we can use only five bits the maximum data-types that can be represented directly is 30. However this limit provides a very safe margin in BER implementation of SNMP. This is because we do not expect (in the near future) SNMP will be using more than 30 datatypes. If it does so, SNMP may not remain simple and may sink under its own weight. Continue reading