Support for secure RPC, secure NFS, and NIS_PLUS Andy Polyakov
<appro@fy.chalmers.se>

- Provides support for secure RPC on systems with keyserv version 1-2.
  Autoconfigured and tested on Solaris 2.5.1 and HP-UX 10.20 boxes.
  It's also possible now to hire keyserv for generating passphrase for
  private key encryption/decryption. If you try to encrypt your key
  with SUN-DES-1 passphrase, ssh-keygen will substitute it with a
  64-bit phrase crypted with your secret RPC key. It's functional
  replacement for ssh-agent. Proc and cons:
  - you use the only password (your login password) to get things
    working;
  - it's invariant to login password as secret key is not changed when
    login password is changed, just reencrypted with new password;
  - if you have your secret key is registered in keyserv, anybody who
    runs under your uid can decrypt your private key (well, same as
    when you keep it in ssh-agent). so it's important to run keylogout
    when you logout or leave and for example lock the screen (i have
    modified version of xlock that keylogout at start and keylogin when
    unlock the screen with your password:-);

- Provides support for secure NFS, autoconfigured and tested on
  Solaris 2.5.1;

- Provides support for NIS+, autoconfigured and tested on Solaris
  2.5.1. Support is forced so that you don't have to recompile if you
  suddenly choose to move to NIS+;

- Ensures that user shell is listed in /etc/shells on systems that
  support getusershell(). The option has to be enabled manually with
  #define CHECK_ETC_SHELLS and tested on Solaris 2.5.1 machine;

- Provides support for password aging on systems with /etc/shadow.
  Tested on Solaris 2.5.1 and IRIX 5.3 machines. /etc/shadow support is
  forced for SGI machines, so that you don't have to recompile if you
  choose to convert it to /etc/shadow.