6. Other programs you may need to upgrade or patch
Even though the shadow suite contains replacement programs for most programs that need to access passwords, there are a few additional programs on most systems that require access to passwords.
If you are running a Debian Distribution (or even if you are not), you can obtain Debian sources for the programs that need to be rebuild from: ftp://ftp.debian.org/debian/stable/source/
The remainder of this section discusses how to upgrade adduser,
wu_ftpd, ftpd, pop3d, xlock,
xdm and sudo so that they support the shadow suite.
See the section Adding Shadow Support to a C program for a discussion on how to put shadow support into any other program that needs it (although the program must then be run SUID root or SGID shadow to be able to actually access the shadow file).
6.1 Slackware adduser program
Slackware distributions (and possibly some others) contain a interactive
program for adding users called /sbin/adduser. A shadow version
of this program can be obtained from
ftp://sunsite.unc.edu/pub/Linux/ system/Admin/accounts/adduser.shadow-1.4.tar.gz.
I would encourage you to use the programs that are supplied with the
Shadow Suite (useradd, usermod, and
userdel) instead of the slackware adduser program. They
take a little time to learn how to use, but it's well worth the effort
because you have much more control and they perform proper file locking on
the /etc/passwd and /etc/shadow file (adduser
doesn't).
See the section on Putting the Shadow Suite to use for more information.
But if you gotta have it, here is what you do:
tar -xzvf adduser.shadow-1.4.tar.gz
cd adduser
make clean
make adduser
chmod 700 adduser
cp adduser /sbin
6.2 The wu_ftpd Server
Most Linux systems some with the wu_ftpd server. If your
distribution does not come with shadow installed, then your wu_ftpd
will not be compiled for shadow. wu_ftpd is launched from
inetd/tcpd as a root process. If you are running an old
wu_ftpd daemon, you will want to upgrade it anyway because older
ones had a bug that would allow the root account to be compromised
(For more info see the
Linux security home page).
Fortunately, you only need to get the source code and recompile it with shadow enabled.
If you are not running an ELF system, The wu_ftp server can be
found on Sunsite as
wu-ftp-2.4-fixed.tar.gz
Once you retrieve the server, put it in /usr/src, then type:
cd /usr/src
tar -xzvf wu-ftpd-2.4-fixed.tar.gz
cd wu-ftpd-2.4-fixed
cp ./src/config/config.lnx.shadow ./src/config/config.lnx
Then edit ./src/makefiles/Makefile.lnx, and change the line:
LIBES = -lbsd -support
LIBES = -lbsd -support -lshadow
Now you are ready to run the build script and install:
cd /usr/src/wu-ftpd-2.4-fixed
/usr/src/wu-ftp-2.4.fixed/build lnx
cp /usr/sbin/wu.ftpd /usr/sbin/wu.ftpd.old
cp ./bin/ftpd /usr/sbin/wu.ftpd
This uses the Linux shadow configuration file, compiles and installs the server.
On my Slackware 2.3 system I also had to do the following before running
build:
cd /usr/include/netinet
ln -s in_systm.h in_system.h
cd -
Problems have been reported compiling this package under ELF systems, but the Beta version of the next release works fine. It can be found as wu-ftp-2.4.2-beta-10.tar.gz
Once you retrieve the server, put it in /usr/src, then type:
cd /usr/src
tar -xzvf wu-ftpd-2.4.2-beta-9.tar.gz
cd wu-ftpd-beta-9
cd ./src/config
Then edit config.lnx, and change:
#undef SHADOW.PASSWORD
#define SHADOW.PASSWORD
cd ../Makefiles
Makefile.lnx
and change:
LIBES = -lsupport -lbsd # -lshadow
LIBES = -lsupport -lbsd -lshadow
cd ..
build lnx
cp /usr/sbin/wu.ftpd /usr/sbin/wu.ftpd.old
cp ./bin/ftpd /usr/sbin/wu.ftpd
Note that you should check your /etc/inetd.conf file to make sure
that this is where your wu.ftpd server really lives. It has been reported
that some distributions place the server daemons in different places, and
then wu.ftpd in particular may be named something else.
6.3 Standard ftpd
If you are running the standard ftpd server, I would recommend that
you upgrade to the wu_ftpd server. Aside from the known bug
discussed above, it's generally thought to be more secure.
If you insist on the standard one, or you need NIS support, Sunsite has ftpd-shadow-nis.tgz
6.4 pop3d (Post Office Protocol 3)
If you need to support the third Post Office Protocol (POP3), you
will need to recompile a pop3d program. pop3d is normally
run by inetd/tcpd as root.
There are two versions available from Sunsite: pop3d-1.00.4.linux.shadow.tar.gz and pop3d+shadow+elf.tar.gz
Both of these are fairly straight forward to install.
6.5 xlock
If you install the shadow suite, and then run X Windows System and
lock the screen without upgrading your xlock, you will have to use
CNTL-ALT-Fx to switch to another tty, login, and kill the
xlock process (or use CNTL-ALT-BS to kill the X server).
Fortunately it's fairly easy to upgrade your xlock program.
If you are running XFree86 Versions 3.x.x, you are probably using
xlockmore (which is a great screen-saver in addition to a lock).
This package supports shadow with a recompile. If you have an
older xlock, I recommend that you upgrade to this one.
xlockmore-3.5.tgz is available at:
ftp://sunsite.unc.edu/pub/Linux/X11/xutils/screensavers/xlockmore-3.7.tgz
Basically, this is what you need to do:
Get the xlockmore-3.7.tgz file and put it in /usr/src unpack it:
tar -xzvf xlockmore-3.7.tgz
Edit the file: /usr/X11R6/lib/X11/config/linux.cf, and change the line:
#define HasShadowPasswd NO
to
#define HasShadowPasswd YES
Then build the executables:
cd /usr/src/xlockmore
xmkmf
make depend
make
Then move everything into place and update file ownerships and permissions:
cp xlock /usr/X11R6/bin/
cp XLock /var/X11R6/lib/app-defaults/
chown root.shadow /usr/X11R6/bin/xlock
chmod 2755 /usr/X11R6/bin/xlock
chown root.shadow /etc/shadow
chmod 640 /etc/shadow
Your xlock will now work correctly.
6.6 xdm
xdm is a program that presents a login screen for X-Windows. Some
systems start xdm when the system is told to goto a specified run
level (see /etc/inittab.
With the Shadow Suite install, xdm will need to be
updated. Fortunately it's fairly easy to upgrade your xdm program.
xdm.tar.gz is available at:
ftp://sunsite.unc.edu/pub/Linux/X11/xutils/xdm.tar.gz
Get the xdm.tar.gz file and put it in /usr/src, then to
unpack it:
tar -xzvf xdm.tar.gz
Edit the file: /usr/X11R6/lib/X11/config/linux.cf, and change the line:
#define HasShadowPasswd NO
to
#define HasShadowPasswd YES
Then build the executables:
cd /usr/src/xdm
xmkmf
make depend
make
Then move everything into place:
cp xdm /usr/X11R6/bin/
xdm is run as root so you don't need to change it file
permissions.
6.7 sudo
The program sudo allows a system administrator to let users run
programs that would normally require root access. This is handy because it
lets the administrator limit access to the root account itself while still
allowing users to do things like mounting drives.
sudo needs to read passwords because it verifies the users password
when it's invoked. sudo already runs SUID root, so accessing the
/etc/shadow file is not a problem.
sudo for the shadow suite, is available as at:
ftp://sunsite.unc.edu/pub/Linux/system/Admin/sudo-1.2-shadow.tgz
Warning: When you install sudo your /etc/sudoers
file will be replaced with a default one, so you need to make a backup of it
if you have added anything to the default one. (you could also edit the
Makefile and remove the line that copies the default file to /etc).
The package is already setup for shadow, so all that's required is to
recompile the package (put it in /usr/src):
cd /usr/src
tar -xzvf sudo-1.2-shadow.tgz
cd sudo-1.2-shadow
make all
make install
6.9 pppd (Point-to-Point Protocol Server)
The pppd server can be setup to use several types of authentication:
Password Authentication Protocol (PAP) and Cryptographic
Handshake Authentication Protocol (CHAP). The pppd server usually
reads the password strings that it uses from /etc/ppp/chap-secrets
and/or /etc/ppp/pap-secrets. If you are using this default behavior
of pppd, it is not necessary to reinstall pppd.
pppd also allows you to use the login parameter (either on the
command line, or in the configuration or options file). If the
login option is given, then pppd will use the /etc/passwd
file for the username and passwords for the PAP. This, of course,
will no longer work now that our password file is shadowed. For pppd-1.2.1d
this requires adding code for shadow support.
The example given in the next section is adding shadow support to
pppd-1.2.1d (an older version of pppd).
pppd-2.2.0 already contains shadow support.
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