Main
Resources
Under glibc2.1, the references for crypt changed. This is apparently a problem for a whole slew of code bases, but I'm only discussing iDirt here. You may be familiar the following scene: 
drey@spire:~/aberd/src > make
Compiling generate.c...
Compiling mkdata.c...
Compiling utils.c...
Linking Generator...utils.o: In function `my_crypt':
/home/drey/aberd/src/utils.c:441: undefined reference to `crypt'
make: *** [../bin/generate] Error 1
OK, I'm missing a library, obviously. So we edit the Makefile: 
# Compiler and Compiler Flags
#
# -DNOCATCH in DEFINES to prevent the AutoUpdater from running.
# -lcrypt in LDFLAGS for most BSD systems.
#
CC      = gcc
LDFLAGS =

Ah, we're missing the -lcrypt -- back into the editor I go... 

# Compiler and Compiler Flags
#
# -DNOCATCH in DEFINES to prevent the AutoUpdater from running.
# -lcrypt in LDFLAGS for most BSD systems.
#
CC      = gcc
LDFLAGS = -lcrypt

We save, and compile. Lo and behold! 

drey@spire:~/aberd/src > make
Linking Generator...utils.o: In function `my_crypt':
/home/drey/aberd/src/utils.c:441: undefined reference to `crypt'
make: *** [../bin/generate] Error 1

Hmm. Not the result we were expecting. Time to look at that Makefile again. Let's look for the code to make the generator... 

# Generator (gen) Target
#
$(BIN)$(GEN): $(GENOBS)
        @$(ECHO) -n 'Linking Generator...'
        @$(CC) -o $(BIN)$(GEN) $(CFLAGS) $(GENOBS)

Hmm ... odd, I don't see a reference to LDFLAGS. Let's try something... 

# Generator (gen) Target
#
$(BIN)$(GEN): $(GENOBS)
        @$(ECHO) -n 'Linking Generator...'
        @$(CC) -o $(BIN)$(GEN) $(CFLAGS) $(GENOBS) $(LDFLAGS)

Save and compile again ... 

drey@spire:~/aberd/src > make
Linking Generator...Stripping Binary...Done
Generating World Files...

Using configuration file: ../data/generate.conf
Using logging file:       ../data/mkdata.log
.
.
.

Now that's the kind of output we want to see! The target for the aberd daemon already contains the $(LDFLAGS) info, so we have no work to do there. At this point your iDirt should compile just fine, barring any errors in the code you may have introduced yourself.