The following systems are known to have these features: AIX v3.x, v4.x BSD/386, FreeBSD, HP-UX 9.x, 10.x IRIX, ISC4.0, Linux, OSF/1 V1.3 and V3.0, SCO 3.2v4 with TCP/IP, SCO ODT 3, SCO 5.0, Solaris 2.x, SunOS 4.1.x, SVR4.x on an Intel x86 and MIPS (UnixWare, Onsite, SINIX, ...), Ultrix 4.4.
There are binary (precompiled) versions available for some of these machines, see the HOWTO.