o Sessions and program names could be different. It depends on YOUR DESIGN. 

o You can have the default port in a inet.h file. When the port is not 
  specified, the default port will be used. Refer to the examples in
  http://www.cs.twsu.edu/~chang/lecture/cs742/program/c/socket/.

1. A possible session could be like this (Just one of them should work.):

$ fileserver abc123 8989 &

or

$ fileserver abc123 &

or 

$ fileserver &
Secret Key: abc123

$ interact abc123 1 kirk:/pub/cs742/README 

or

$ interact 8989 abc123 1 kirk:/pub/cs742/README 

or 

$ interact 8989
Secret Key: abc123
Operation: 1. Read, 2. Write, or 3. Stat => 1
Hostname: kirk.cs.twsu.edu
Pathname: /pub/cs742/README
Number of bytes to read or write:
String to be written:

This is the readme file.
Apache 2.0.43  is the best available version.

This release fixes a security problem described in CAN-2002-0840 on 
cve.mitre.org. It also fixes some bugs from 2.0.42 (and earlier) as well as 
adding some additional capability. All users of Apache 2.0.42 and prior are 
urged to upgrade as soon as possible.

$ interact 8989
Secret Key: abc123
Wrong Secret Key! Try again!
Secret Key: 123abc
Wrong Secret Key! Try again!
Secret Key: 123abc
Wrong Secret Key! Bye!

$ interact
Secret Key: 123abc


2. A concatenate session could be like:

$ concate abc123 /tmp/file1.txt sisko:/tmp/file2.txt /tmp/file2.txt

or

$ concate
Secret Key: abc123
Local File: /tmp/file1.txt
Remote File: sisko:/tmp/file2.txt
new File: file2.txt