ok only for the record that src/utils/net/ip.ml patch-snippet in the original submission description for let valid is bull, i think. "i>=0..." is right. for example 186.123.6.0 is a valid ip if it is in the network with the netmask 255.255.0.0 .
it's a protocol limitation of edonkey that these ips (with a zero at the end) fall in the low-id range.

Excluded from the patch was the following section, since this needs a more sophisticated solution. However, this section might be needed to prove the useability of the patch.
Index: src/utils/net/ip.ml
===================================================================
--- src/utils/net/ip.ml (Revision 137)
+++ src/utils/net/ip.ml (Arbeitskopie)
@@ -84,7 +84,7 @@
   j > 0 && j < 224 &&
   k >= 0 && k <= 255 &&
   l >= 0 && l <= 255 &&
-  i >= 0 && i <= 255
+  i > 0 && i <= 255

 let reachable ip =
   !allow_local_network ||