clients.py

#!/usr/bin/python3
# Read Clients from cients.conf
# Requires: ipaddress, freeradius
#
#
# (c) 2019 by Klaus Kappel <kkappel@jugendhilfe-wuemmetal.de>

import ipaddress

FN = '/etc/freeradius/3.0/clients.conf'

class Client:
    def __init__(self, Name, IP):
        self.Name = Name
        self.IP = ipaddress.ip_address(IP)
    def display(self):
        '''
        '''
        print('%32s: %s' % (self.Name, self.IP))


class Clients:
    def __init__(self, FN):
        '''
        Read Clients from FileName
        and list them in Object.
        '''
        self.FN = FN
        self.clients = []
        w = {}
        fh = open(FN, 'r')

        for line in fh:
            if line[0:6] == 'client':
                sect = 1
            elif line.find('}') < 0:
                line = line.strip()
                if line.find('=') > -1:
                    z = line.split('=')
                    z[0] = z[0].strip()
                    z[1] = z[1].strip()            
                    if z[0] == 'shortname':
                        w['name'] = z[1]
                        c = Client(w['name'], w['ip'])
                        self.clients.append(c)
                    elif z[0] == 'ipaddr':
                        w['ip'] = z[1]
            else:
                sect = 0
                w = {}
        
        fh.close()
        return 

    def list(self):
        '''
        list sorted by Name
        '''
        self.clients.sort(key=lambda x: x.Name, reverse=False)
        for l in self.clients:
            l.display()

    def Ips(self):
        '''
        sort by IP-Address
        '''
        self.clients.sort(key=lambda x: x.IP, reverse=False)
        for l in self.clients:
            l.display()

            
if __name__ = '__main__':
    radius = Clients(FN)

    # radius.list()                                                                                                          
    # or                                                                                                                     

Even better for testing.