Rebuilding the latest ,vsftpd-1.0.1-1, I note it tosses off a couple of cast warnings: gcc -c sysdeputil.c -O2 -march=i386 -mcpu=i686 -Wall -W -Wshadow -idirafter dummyinc sysdeputil.c: In function `vsf_sysdep_check_auth': sysdeputil.c:203: warning: implicit declaration of function `crypt' sysdeputil.c:203: warning: assignment makes pointer from integer without a cast sysdeputil.c:211: warning: assignment makes pointer from integer without a cast gcc -o vsftpd main.o utility.o prelogin.o ftpcmdio.o postlogin.o privsock.o tunables Given the notorious scrutiny which FTP Daemons recieve for people looking for escalated priv's, it might make sence to add the prototype and explicit cast.
I can't reproduce this here... in all tests I run, it finds the prototype for crypt just fine. (That's where the other two warnings come from as well, assigning the results of crypt())