diff --git a/install.py b/install.py
index 5759eb6..9d3198e 100755
--- a/install.py
+++ b/install.py
@@ -17,8 +17,22 @@ os.chdir('/root/aputools/to_system')
 DEL = '__to_delete__'
 CFGPATH = '/root/aputools/servercfg/%s.cfg'
 
-def create_if(name, mac, cfg):
-    result=dict(
+
+def write_when_new(filename, content, doit):
+    if not content.endswith('\n'):
+        content += '\n'
+    with open(filename) as fil:
+        old = fil.read()
+    if old == content:
+        return False
+    if doit:
+        with open(filename, 'w') as fil:
+            fil.write(content)
+    return True
+
+
+def create_if(name, cfg):
+    result = dict(
         TYPE='Ethernet',
         NAME=name,
         DEVICE=name,
@@ -36,7 +50,7 @@ def create_if(name, mac, cfg):
         interface = IPv4Interface(cfg)
         if '/' not in cfg:
             if interface < IPv4Interface('128.0.0.0'):
-                cfg += '/8' 
+                cfg += '/8'
             elif interface < IPv4Interface('192.0.0.0'):
                 cfg += '/16'
             else:
@@ -45,7 +59,7 @@ def create_if(name, mac, cfg):
         result['IPADDR'], result['NETMASK'] = interface.with_netmask.split('/')
         _, result['PREFIX'] = interface.with_prefixlen.split('/')
     return result
-    
+
 
 def walk(action):
     for dirpath, _, files in os.walk('.'):
@@ -77,37 +91,39 @@ def walk(action):
                 if missing:
                     action.missing(missing)
 
+
 class Show:
     dirty = False
 
     def show(self, title, files):
         self.dirty = True
         print('%s %s:\n  %s' % (title, self.syspath, ' '.join(files)))
-        
+
     def newer(self, files):
         self.show('get from', files)
-        
+
     def older(self, files):
         self.show('replace in', files)
-        
+
     def missing(self, files):
         self.show('install in', files)
-        
+
     def delete(self, files):
         self.show('remove from', files)
 
+
 class Do:
     def newer(self, files):
         for file in files:
             shutil.copy(join(self.syspath, file), join(self.dirpath, file))
-        
+
     def older(self, files):
         for file in files:
             shutil.copy(join(self.dirpath, file), join(self.syspath, file))
-        
+
     def missing(self, files):
         self.older(files)
-        
+
     def delete(self, files):
         for file in files:
             os.remove(join(self.syspath, file))
@@ -115,65 +131,58 @@ class Do:
 
 IFNAMES = ['enp%ds0' % i for i in range(1,5)]
 
+
 def network(doit):
-    result = True
     netaddr_dict = {}
     for ifname in IFNAMES:
         with open('/sys/class/net/%s/address' % ifname) as f:
             netaddr_dict[ifname] = f.read().strip().lower()
     netaddr = netaddr_dict[IFNAMES[0]]
-    action = 'doit' if doit else 'check'
-    addrdict = {}
-    for cfgfile in glob(CFGPATH % '*'):
-        parser = ConfigParser()
-        try:
-            parser.read(cfgfile)
-            address = parser['NETWORK']['address'].lower()
-            if address in addrdict:
-                print(cfgfile)
-                print(addrdict[address])
-                print('ERROR: duplicate address %s in above files' % address)
-            addrdict[address] = cfgfile
-        except Exception as e:
-            print('ERROR: can not read %s: %r' % (cfgfile, e))
-            result = False
-    cfgfile = addrdict.get(netaddr)
-    if cfgfile is None:
-        print('can not find cfg file for %s' % netaddr)
-        result = False
+    apuid = int(''.join(netaddr.split(':')[-3:]), 16) & 0xfffffc
+    cfgfile = None
+    cfgfiles = []
+    for i in range(4):
+        # goodie: look for mac addresses of all 4 ports
+        cfgfiles += glob(CFGPATH % ('*_%6.6x' % (apuid + i)))
+    if not cfgfiles:
+        print('no cfg file found for %s' % netaddr)
+    elif len(cfgfiles) > 1:
+        print('ERROR: ambiguous cfg files: %s' % ', '.join(cfgfiles))
+    else:
+        cfgfile = cfgfiles[0]
     for ntry in range(1 + bool(doit)):
         with open('/etc/hostname') as f:
             hostname = f.read().strip()
-        if CFGPATH % hostname == cfgfile:
+        if hostname == cfgfile[:-7]:  # stripped apuid from cfgfile
             break
         if doit:
             if ntry == 0:
                 os.system('sh sethostname.sh')
-            else: 
+            else:
                 print('ERROR: can not set host name')
-                result = False
+                return False
         else:
             print('host name does not match')
             break
-    if not result:
+    if cfgfile is None:
         return False
     ifname = ''
     parser = ConfigParser()
     try:
-        parser.read(CFGPATH % hostname)
+        parser.read(cfgfile)
         network = dict(parser['NETWORK'])
-        address = network.pop('address', None)
-        main = None
         for ifname in IFNAMES:
-            content = create_if(ifname, netaddr_dict[ifname],
-                                network.get(ifname, 'off'))
-            with open('etc/sysconfig/network-scripts/ifcfg-%s' % ifname, 'w') as f:
-                f.write('\n'.join('%s=%s' % kv for kv in content.items())+ '\n')
+            content = create_if(ifname, network.get(ifname, 'off'))
+            content = '\n'.join('%s=%s' % kv for kv in content.items())
+            todo = write_when_new('/etc/sysconfig/network-scripts/ifcfg-%s' % ifname, content, doit)
+            if todo:
+                print('change ', ifname)
     except Exception as e:
         print('ERROR: can not handle %s %s: %r' % (hostname, ifname, e))
-        result = False
-    return result
-    
+        return False
+    return True
+
+
 print('---')
 show = Show()
 result = network(False)
diff --git a/servercfg/apumaster.cfg b/servercfg/apumaster_591fac.cfg
similarity index 100%
rename from servercfg/apumaster.cfg
rename to servercfg/apumaster_591fac.cfg
diff --git a/servercfg/apuslave1.cfg b/servercfg/apuslave1_5920a8.cfg
similarity index 100%
rename from servercfg/apuslave1.cfg
rename to servercfg/apuslave1_5920a8.cfg
diff --git a/servercfg/apuslave3.cfg b/servercfg/apuslave3_5a4c90.cfg
similarity index 100%
rename from servercfg/apuslave3.cfg
rename to servercfg/apuslave3_5a4c90.cfg
diff --git a/servercfg/dilsc.cfg b/servercfg/dilsc_5a58e4.cfg
similarity index 100%
rename from servercfg/dilsc.cfg
rename to servercfg/dilsc_5a58e4.cfg