Build a macOS dylib rather than a shared library.
--- src/Makefile.in.orig	2021-07-29 11:44:40.000000000 -0500
+++ src/Makefile.in	2021-07-29 11:44:40.000000000 -0500
@@ -13,7 +13,7 @@
 libdir		= @libdir@
 mandir		= @mandir@
 LIBSTATIC      = libnids.a
-LIBSHARED      = libnids.so.1.24
+LIBSHARED      = libnids.1.24.dylib
 
 CC		= @CC@
 CFLAGS		= @CFLAGS@ -DLIBNET_VER=@LIBNET_VER@ -DHAVE_ICMPHDR=@ICMPHEADER@ -DHAVE_TCP_STATES=@TCPSTATES@ -DHAVE_BSD_UDPHDR=@HAVE_BSD_UDPHDR@
@@ -65,7 +65,7 @@
 	ar -cr $@ $(OBJS)
 	$(RANLIB) $@
 $(LIBSHARED): $(OBJS_SHARED)
-	$(CC) -shared -Wl,-soname,$(LIBSHARED) -o $(LIBSHARED) $(OBJS_SHARED) $(LDFLAGS) $(LIBS) $(LNETLIB) $(PCAPLIB)
+	$(CC) -dynamiclib -Wl,-install_name,$(libdir)/$(LIBSHARED) -current_version 1.0.0 -compatibility_version 1.0.0 -o $(LIBSHARED) $(OBJS_SHARED) $(LDFLAGS) $(LIBS) $(LNETLIB) $(PCAPLIB)
 
 _install install: $(LIBSTATIC)
 	../mkinstalldirs $(install_prefix)$(libdir)
@@ -76,7 +76,7 @@
 	$(INSTALL) -c -m 644 libnids.3 $(install_prefix)$(mandir)/man3
 _installshared installshared: install $(LIBSHARED)
 	$(INSTALL) -c -m 755 $(LIBSHARED) $(install_prefix)$(libdir)
-	ln -s -f $(LIBSHARED) $(install_prefix)$(libdir)/libnids.so
+	ln -s -f $(LIBSHARED) $(install_prefix)$(libdir)/libnids.dylib
  
 clean:
 	rm -f *.o *~ $(LIBSTATIC) $(LIBSHARED)