support the case of no enp0 if is present

if seems on ionopimax, with predictable network IF on, the
main (only) interface is named enx....... instead of end0
this is a fix to support it

sethostname.sh

@@ -1,12 +1,12 @@
 if [[ -f /sys/class/net/end0/address ]]; then
   ETHNAME=$(cat /sys/class/net/end0/address)
   BASED=end0
-else
+elif [[ -f /sys/class/net/eth0/address ]]; then
   ETHNAME=$(cat /sys/class/net/eth0/address)
-  if [[ -z "$ETHNAME" ]]; then
-    ETHNAME=undefined
-  fi
   BASED=eth0
+else
+  ETHNAME=$(cat /sys/class/net/en*/address)
+  BASED=$(echo /sys/class/net/en*/address)
 fi
 FOUND=($(grep -l -r MAC=$ETHNAME /home/l_samenv/boxtools/cfg))
 if [ -z "$FOUND" ]; then

to_system/etc/profile.d/welcome.sh

@@ -1,10 +1,12 @@
 export EDITOR=nano
 echo "-----------------------------------------------------"
 echo "Welcome to $HOSTNAME $(hostname -I)"
-if [[ -f /sys/class/net/eth0/address ]]; then
+if [[ -f /sys/class/net/end0/address ]]; then
+  ETHNAME=$(cat /sys/class/net/end0/address)
+elif [[ -f /sys/class/net/eth0/address ]]; then
   ETHNAME=$(cat /sys/class/net/eth0/address)
 else
-  ETHNAME=$(cat /sys/class/net/end0/address)
+  ETHNAME=$(cat /sys/class/net/en*/address)
 fi
 echo "ethernet addr $ETHNAME"
 function service_status () {

utils.py

@@ -98,6 +98,14 @@ class BoxInfo:
                 if ifname in ('eth0', 'enp1s0', 'end0'):
                     macaddr = addr
                     self.main_if = ifname
+        if self.main_if is None:
+            if len(self.network_interfaces) == 1:
+                self.main_if = list(self.network_interfaces)[0]
+                macaddr = self.network_interfaces[self.main_if]
+            elif self.network_interfaces:
+                raise RuntimeError(f'ambiguous main if: {self.network_interfaces}')
+            else:
+                raise RuntimeError('no main if found')
         self.macaddr = macaddr
         if macaddr:
             self.id = int(''.join(macaddr.split(':')[-3:]), 16) & 0xffffff