PNETLab Cisco IOL License Fix

Network Automation Utility • Troubleshooting Guide

This utility automates the cleanup of IOUkeygen errors and simplifies the generation of Cisco IOL licenses within PNETLab environments. Use the steps below for manual correction or download the automation script.

Step 1: Clean and Replace Script

Deploy the following Python logic into /opt/unetlab/addons/iol/bin/IOUkeygen.py to ensure clean execution:

#!/usr/bin/python
import os
import socket
import hashlib
import struct

hostid = os.popen("hostid").read().strip()
hostname = socket.gethostname()
ioukey = int(hostid, 16)
for x in hostname:
    ioukey = ioukey + ord(x)

iouPad1 = b'\x4B\x58\x21\x81\x56\x7B\x0D\xF3\x21\x43\x9B\x7E\xAC\x1D\xE6\x8A'
iouPad2 = b'\x80' + 39*b'\0'
md5input = iouPad1 + iouPad2 + struct.pack('!i', ioukey) + iouPad1
iouLicense = hashlib.md5(md5input).hexdigest()[:16]

print("*********************************************************************")
print("Cisco IOU License Generator")
print("hostid=" + hostid + ", hostname=" + hostname + ", ioukey=" + hex(ioukey)[2:])
print("\nAdd the following text to /opt/unetlab/addons/iol/bin/iourc:")
print("[license]\n" + hostname + " = " + iouLicense + ";")
print("*********************************************************************")

Step 2: Apply the License

Reference: License generation output example

Once the script is executed, generate your iourc file using the generated key:

echo -e "[license]\npnetlab = b126e08dae13e962;" > /opt/unetlab/addons/iol/bin/iourc

Step 3: Fix Permissions

Always conclude by running the wrapper utility to fix filesystem permissions:

/opt/unetlab/wrappers/unl_wrapper -a fixpermissions

Enterprise Automation

For large-scale deployments or rapid recovery, use our automated shell utility to execute all three steps simultaneously:

At I AM TAC, we optimize infrastructure workflows to ensure your labs remain operational without licensing bottlenecks.