Ident protocol

Ident is a network protocol that allows a server can determine which users of a multi-user system has opened a particular TCP connection. Ident used the Transmission Control Protocol on port 113 and is specified in RFC 1413 specified.

The use of an ident server good is it only the operator of the system in question to himself: he can identify in the complaint case on the basis of information recorded by the complainant Ident response to the originator of the TCP connection in question on his system. For other than the person who operates the ident server, the information of the Ident protocol are useless because potentially falsified.

There are a number of programs with identification functionality that return either deliberate falsification or validated information; This is justified by the fact that the protocol could be a security deficit and will in addition interfered with the personal rights of local users.

Ident messages always consist of a line of ASCII text, which is terminated by a newline with the .

A request is as follows:

, Valid responses repeat the request and have one of the following forms:

, : USERID: , : ERROR: Areas of the Ident Protocol, for example,

• Simple Mail Transfer Protocol: Provided an ident request to the sending system in the adoption of an email and added the ID response in the headers of the email, so is the operator of the sender system able to later assign fake mails to its users
• Internet Relay Chat: This allows, for example, the channel operator to exclude only a single user of the discussion instead of a whole host

Example Scenario

A user " file" on the client computer 10.10.10.10 establishes a connection to the SMTP server 10.20.20.20:25 with any client port 31010.

The SMTP daemon establishes a connection from 10.20.20.20 with any client port 42020 to connect to the ident daemon on the client 10.10.10.10:113. He asks which user has created a connection from source port 31010 to destination port 25:

31010, 25

The ident daemon has searchable interface to the TCP / IP stack of the operating system, a table for the corresponding TCP connection. This IP and port for source and destination are compared. The ident daemon then responds with the operating system identifier his server, " UNIX", and the name of the owner of the TCP connection, " file":

31010, 25: USERID: UNIX: tei