It seems that pidentd just doesn't work on alpha. I've got ssh with TCP wrappers enabled and, when I try to connect from alpha workstations running RedHat 6.1 and 6.2, identd will always return an error. I've just rebuilt pidentd 3.0.10 from the original sources (not from the SRPM), using GCC 2.95.2, and it is now working fine.
*** This bug has been marked as a duplicate of 10752 ***