Python For Network Engineers 1

Python For Network Engineers 1

(1) Network programmability made easy

Router-1

• Basic configuration
  • config terminal
  • hostname R1
• Configure IP interface
  • interface gig0/0
  • ip address 192.168.122.71 255.255.255.0
  • no shut
• Enable remote management access (Telnet)
  • enable password cisco
  • username admin password cisco
  • line vty 0 4
  • login local
  • transport input all
• Debugging
  • debug telnet

Ubuntu-1

• Test internet connectivity
  • ping google.com = [OK]
• Update references in Ubuntu
  • apt-get update
    • > Downloads the package lists from the repositories and “updates” them to get information on the newest versions of packages and their dependencies.
    • > It will do this for all repositories and PPAs
• Install Python 2.7.X
  • apt-get install python
• Enter python shell
  • python
  • quit()
    • > To quit python shell
• Create Python script
  • nano pythonR1
  • Paste the Python 2.7.X Telnet Example (Figure 2)
  • Modified as necessary (Figure 3)
• Run Python script
  • python pythonR1 (Figure 4)
  • Enter username: admin
  • Enter password: cisco
  • It will also print all the commands that we send to the router
  • Router debug output (Figure 5)

(2) Remove enable password and improve script

Router-1

• Add privilege level 15 to the “python” user
  • user python privilege 15 password cisco

Ubuntu-1

• Use Python script file extension (Figure 1)
  • cp pythonR1 S1script2.py
  • nano S1script2.py
  • Notice there is text color (because of the extension)
  • The “#!” indicates which interpreter to use, in this case python
• Run the script without command “python”
  • S1script2.py
    • >bash: command not found
  • chmod +x ./S1script2.py
    • > To change the permission on the script, to make it executable
  • ./S1script2.py
    • > Now the script is able to run
    • > “./” is to call a file in the local directory
• Remove the enable password steps (Figure 2)
  • nano S1script2.py
  •  ./S1script2.py
    • > Use “python” username