Just a quick hacky script to generate dhcp option 43 for Cisco LAPs to join Wireless Lan Controllers (WLC). This script outputs a line to add to your dhcpd.conf subnet declaration. It takes a list of IPs as arguments and will convert them into a suitable dhcpd.conf entry.
Script invocation example:
user@work:~$ ./gen-dhcp-43.py 192.168.10.5 192.168.10.20
Please add the following line to the correct subject declaration.
option vendor-encapsulated-options f1:08:c0:a8:0a:05:c0:a8:0a:14;
Example subnet declaration
subnet 192.168.10.0 netmask 255.255.255.0 {
range dynamic-bootp 192.168.10.0 192.168.10.255;
option broadcast-address 192.168.10.255;
option routers 192.168.10.1;
option vendor-encapsulated-options f1:08:c0:a8:0a:05:c0:a8:0a:14;
max-lease-time 604800;
default-lease-time 604800;
host hostname {
hardware ethernet xx:xx:xx:xx:xx:xx;
fixed-address 192.168.10.10;
}
}
Script
#!/usr/bin/env python3
#
# Configure Cisco LAPs to join WLC via dhcpd option 43.
# 11/16/2021 [email protected]
import sys
if len(sys.argv) < 1:
print(f"Usage: {sys.argv[0]} <ip1> <ip2> <...>")
exit(1)
def gen_hex(ip):
ipsplit = ip.split('.')
hexxed = ':'.join(hex(int(i))[2:].zfill(2) for i in ipsplit)
return(hexxed)
def gen_prefix(num):
type = "f1"
length = hex(int(num * 4))[2:].zfill(2)
return(f"{type}:{length}")
num_ips = len(sys.argv) - 1
prefix = gen_prefix(num_ips)
hexips = []
for ip in sys.argv[1:]:
iphex = gen_hex(ip)
hexips.append(iphex)
hexips = ':'.join(hexips)
print("Please add the following line to the correct subject declaration.")
print(f"option vendor-encapsulated-options {prefix}:{hexips};")
