EForward uses a three-part (client-server-client) model, capable of handling any file type without further processing.
Eforward was created in 1992 and in 1999 was assigned the IP port number 2181 by the Internet Assigned Numbers Authority (IANA). The protocol continues to be used under the Secure Easy IM (Seim) name. Originally the protocol was peer to peer but was changed to client server with peer to peer features. The protocol has both encrypted and unencrypted modes. The encryption is highly automatic and has been patented. EForward uses one port, 2181, in either TCP or UDP mode to transfer files between a client and the server. The major objective of the protocol is to provide a known level of service: The documents sent from one client to another should never be in an unknown state, at any time. This is done by having the server keep track of the state of all the messages, and having it be the definitive status keeper.
The other objective of the protocol is to allow clients to connect at their convenience for either sending or receiving data: They can send to any other client at any time, and receive any messages they have been sent to them at any time. Alternatively, they can be notified by the server when they have new messages.
In general communication via EForward happens in three stages:
- Client A sends a message for Client B to the server.
- Client B is notified by the server that there are new messages for it.
- Client B retrieves the message from the server.
EForward is designed specifically to transport documents between companies, particularly when the loss of a document cannot be allowed. Currently it is primarily used by the shipping/transport industry to handle shipping instructions and messages between shipping companies, ports, manufacturers and resalers.
- Trivial File Transfer Protocol (TFTP)
- SSH file transfer protocol (sftp), a protocol running over SSH
- Secure FTP, FTP run over SSH
- FTPS, FTP run over SSL
- Simple File Transfer Protocol (SFTP), the historic protocol RFC 913