Okay, I've narrowed the problem down quite a bit. As previously reported, in CentOS 5.2 I get this: $ cvs log Makefile poll: protocol failure in circuit setup cvs [log aborted]: end of file from server (consult above messages if any) Turns out this is a problem with rsh: $ rsh khan ls connect to address 10.24.15.48 port 544: Connection refused Trying krb4 rsh... connect to address 10.24.15.48 port 544: Connection refused trying normal rsh (/usr/bin/rsh) poll: protocol failure in circuit setup Now, if I just reomtely login to khan (our cvs server), I get this: [mrichter at sushi ~]$ khan connect to address 10.24.15.48 port 543: Connection refused Trying krb4 rlogin... connect to address 10.24.15.48 port 543: Connection refused trying normal rlogin (/usr/bin/rlogin) Last login: Fri Jul 4 18:19:01 from viper [mrichter at khan mrichter]$ Voila - I'm logged in. Also, if I try an rsh from another machine (viper - FC1), I get this: [mrichter at viper mrichter]$ rsh khan ls connect to address 10.24.15.48: Connection refused Trying krb4 rsh... connect to address 10.24.15.48: Connection refused trying normal rsh (/usr/bin/rsh) Desktop Documents Download Music Pictures Public Templates Videos bin lane608 rls_607 temp.xml So, what is it about rsh from CentOS 5.2 such that the kerberos certification destroys its chances of success? Alternative question: what do I need to tweak to make this work? Thanks. mhr PS: Google has lots of wrong answers on this, mostly really old and of no use at all.