Difference between revisions of "MIT krb5"

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(I cleaned up the page.)
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  '''Note:'''
 
  '''Note:'''
−
  Some sort of time synchronization facility on your system (like [[NTP]])
+
  A time synchronization facility of some sort (like [[NTP]]) is needed on your system
−
  is required since Kerberos won't authenticate if the time differential
+
  if you're going to be using Kerberos. Kerberos won't authenticate if the time
−
  between a kerberized client and the KDC server is more than 5 minutes.
+
  differential between a kerberized client and the KDC server is more than 5 minutes.
 +
And since you'll probably want Kerberos to be able to authenticate, you'll want
 +
to synchronize the time between teh client and the server.
  
 
== Non-Multilib ==
 
== Non-Multilib ==
  
−
MIT krb5 is distributed in a TAR file containing a compressed TAR package and a detached PGP ASC file.
+
Build the packge:
  
−
If you have installed [[GnuPG]], you can authenticate the package with the following command:
+
  cd src
−
 
+
  ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var/lib
−
gpg - -verify krb5-1.4.1.tar.gz.asc
+
    --enable-dns --enable-static --mandir=/usr/share/man
−
 
 
−
Build MIT krb5 by running the following commands:
 
−
 
 
−
  cd src &&
 
−
  ./configure --prefix=/usr --sysconfdir=/etc \
 
−
    --localstatedir=/var/lib --enable-dns \
 
−
    --enable-static --mandir=/usr/share/man &&
 
 
  make
 
  make
  
 
Install the package:
 
Install the package:
  
−
  make install &&
+
  make install
−
  mv -v /usr/bin/ksu /bin &&
+
  mv -v /usr/lib/libdes425.so.3* /lib
−
  mv -v /usr/lib/libkrb5.so.3* /lib &&
+
  mv -v /usr/lib/libk5crypto.so.3* /lib
−
  mv -v /usr/lib/libkrb4.so.2* /lib &&
+
  mv -v /usr/lib/libkrb5.so.3* /lib
−
  mv -v /usr/lib/libdes425.so.3* /lib &&
+
  mv -v /usr/lib/libkrb4.so.2* /lib
−
  mv -v /usr/lib/libk5crypto.so.3* /lib &&
+
  mv -v /usr/lib/libcom_err.so.3* /lib
−
  mv -v /usr/lib/libcom_err.so.3* /lib &&
+
  mv -v /usr/bin/ksu /bin
−
  ln -v -sf ../../lib/libkrb5.so.3 /usr/lib/libkrb5.so &&
+
  ln -v -sf ../../lib/libkrb4.so.2 /usr/lib/libkrb4.so
−
  ln -v -sf ../../lib/libkrb4.so.2 /usr/lib/libkrb4.so &&
+
  ln -v -sf ../../lib/libkrb5.so.3 /usr/lib/libkrb5.so
−
  ln -v -sf ../../lib/libdes425.so.3 /usr/lib/libdes425.so &&
+
  ln -v -sf ../../lib/libk5crypto.so.3 /usr/lib/libk5crypto.so
−
  ln -v -sf ../../lib/libk5crypto.so.3 /usr/lib/libk5crypto.so &&
+
  ln -v -sf ../../lib/libcom_err.so.3 /usr/lib/libcom_err.so
−
  ln -v -sf ../../lib/libcom_err.so.3 /usr/lib/libcom_err.so &&
+
  ln -v -sf ../../lib/libdes425.so.3 /usr/lib/libdes425.so
 
  ldconfig
 
  ldconfig
  
 
  <font color=red>'''Warning:'''</font>
 
  <font color=red>'''Warning:'''</font>
−
  '''login.krb5''' does not support shadow passwords. As a result, when the Kerberos
+
  '''login.krb5''' does not support shadow passwords. So, when the Kerberos
−
  server is unavailable, the default fall through to '''/etc/password''' will not work
+
  server is unavailable, the default use of '''/etc/password''' will not work
−
  because the passwords have been moved to '''/etc/shadow''' during the CLFS build
+
  because the passwords are now in '''/etc/shadow''' (where they were put while
−
  process. Entering the following commands without moving the passwords back
+
  building CLFS). Entering the following commands without moving the passwords back
 
  to '''/etc/password''' could prevent any logins.
 
  to '''/etc/password''' could prevent any logins.
  
−
If Linux-Pam is not installed and you understand the above warning, the following can be entered:
+
If you understand the above warning and Linux-Pam is not installed, the following commands can be used:
  
 
  mv -v /bin/login /bin/login.shadow &&
 
  mv -v /bin/login /bin/login.shadow &&
 
  cp -v /usr/sbin/login.krb5 /bin/login
 
  cp -v /usr/sbin/login.krb5 /bin/login
  
−
If CrackLib is installed, or if any word list has been put in /usr/share/dict, the following should be entered:
+
If CrackLib is installed, or if any word list has been put in /usr/share/dict, the following commands should be used:
  
 
  ln -s /usr/share/dict/words /var/lib/krb5kdc/kadmin.dict
 
  ln -s /usr/share/dict/words /var/lib/krb5kdc/kadmin.dict
Line 77: Line 72:
 
--enable-static: This switch builds static libraries in addition to the shared libraries.
 
--enable-static: This switch builds static libraries in addition to the shared libraries.
  
−
'''mv -v /bin/login /bin/login.shadow && cp -v /usr/sbin/login.krb5 /bin/login && mv -v /usr/bin/ksu /bin''': Preserves Shadow's '''login''' command, moves '''ksu''' and '''login''' to the /bin directory.
+
'''mv -v /bin/login /bin/login.shadow && cp -v /usr/sbin/login.krb5 /bin/login && mv -v /usr/bin/ksu /bin''': Preserves Shadow's '''login''' command, moves '''ksu''' and '''login''' by moving them to the /bin directory.
  
−
'''mv -v ... /lib && ln -v -sf ...''': The '''login''' and '''ksu''' programs are linked against these libraries, therefore these libraries are moved to /lib to allow logins without mounting /usr.
+
'''mv -v ... /lib''' and '''ln -v -sf ...''': The '''login''' and '''ksu''' programs are linked against these libraries, so these libraries are moved to /lib in order to allow logins without mounting /usr.
  
 
== Multilib ==
 
== Multilib ==
Line 97: Line 92:
 
== Configuring ==
 
== Configuring ==
  
−
=== Configuration Files ===
+
See [http://www.linuxfromscratch.org/blfs/view/svn/postlfs/mitkrb.html#krb5-config BLFS' MIT krb5 page] for how to configure Kerberos.
−
 
 
−
/etc/krb5.conf and /var/lib/krb5kdc/kdc.conf
 
−
 
 
−
=== Kerberos Configuration ===
 
−
 
 
−
Create the Kerberos configuration file with the following command:
 
−
 
 
−
<pre>
 
−
cat > /etc/krb5.conf << "EOF"
 
−
# Begin /etc/krb5.conf
 
−
 
−
[libdefaults]
 
−
    default_realm = <LFS.ORG>
 
−
    encrypt = true
 
−
 
−
[realms]
 
−
    <LFS.ORG> = {
 
−
        kdc = <belgarath.lfs.org>
 
−
        admin_server = <belgarath.lfs.org>
 
−
    }
 
−
 
−
[domain_realm]
 
−
    .<lfs.org> = <LFS.ORG>
 
−
 
−
[logging]
 
−
    kdc = SYSLOG[:INFO[:AUTH]]
 
−
    admin_server = SYSLOG[INFO[:AUTH]]
 
−
    default = SYSLOG[[:SYS]]
 
−
 
−
# End /etc/krb5.conf
 
−
EOF
 
−
</pre>
 
−
 
 
−
You will need to substitute your domain and proper hostname for the occurences of the <belgarath> and <lfs.org> names.
 
−
 
 
−
default_realm should be the name of your domain changed to ALL CAPS. This isn't required, but both Heimdal and MIT recommend it.
 
−
 
 
−
encrypt = true provides encryption of all traffic between kerberized clients and servers. It's not necessary and can be left off. If you leave it off, you can encrypt all traffic from the client to the server using a switch on the client program instead.
 
−
 
 
−
The [realms] parameters tell the client programs where to look for the KDC authentication services.
 
−
 
 
−
The [domain_realm] section maps a domain to a realm.
 
−
 
 
−
Create the KDC database:
 
−
 
 
−
kdb5_util create -r <LFS.ORG> -s
 
−
 
 
−
Now you should populate the database with principles (users). For now, just use your regular login name or root.
 
−
 
 
−
kadmin.local
 
−
kadmin: add_policy dict-only
 
−
kadmin: addprinc -policy dict-only <loginname>
 
−
 
 
−
The KDC server and any machine running kerberized server daemons must have a host key installed:
 
−
 
 
−
kadmin: addprinc -randkey host/<belgarath.lfs.org>
 
−
 
 
−
After choosing the defaults when prompted, you will have to export the data to a keytab file:
 
−
 
 
−
kadmin: ktadd host/<belgarath.lfs.org>
 
−
 
 
−
This should have created a file in /etc named krb5.keytab (Kerberos 5). This file should have 600 (root rw only) permissions. Keeping the keytab files from public access is crucial to the overall security of the Kerberos installation.
 
−
 
 
−
Eventually, you'll want to add server daemon principles to the database and extract them to the keytab file. You do this in the same way you created the host principles. Below is an example:
 
−
 
 
−
kadmin: addprinc -randkey ftp/<belgarath.lfs.org>
 
−
kadmin: ktadd ftp/<belgarath.lfs.org>
 
−
 
 
−
Exit the '''kadmin''' program (use '''quit''' or '''exit''') and return back to the shell prompt. Start the KDC daemon manually, just to test out the installation:
 
−
 
 
−
/usr/sbin/krb5kdc &
 
−
 
 
−
Attempt to get a ticket with the following command:
 
−
 
 
−
kinit <loginname>
 
−
 
 
−
You will be prompted for the password you created. After you get your ticket, you can list it with the following command:
 
−
 
 
−
klist
 
−
 
 
−
Information about the ticket should be displayed on the screen.
 
−
 
 
−
To test the functionality of the keytab file, issue the following command:
 
−
 
 
−
ktutil
 
−
ktutil: rkt /etc/krb5.keytab
 
−
ktutil: l
 
−
 
 
−
This should dump a list of the host principal, along with the encryption methods used to access the principal.
 
−
 
 
−
At this point, if everything has been successful so far, you can feel fairly confident in the installation and configuration of the package.
 
−
 
 
−
Install the /etc/rc.d/init.d/kerberos init script included in the [http://www.linuxfromscratch.org/blfs/view/svn/introduction/bootscripts.html blfs-bootscripts] package.
 
−
 
 
−
make install-kerberos
 
−
 
 
−
=== Using Kerberized Client Programs ===
 
−
 
 
−
To use the kerberized client programs ('''telnet''', '''ftp''', '''rsh''', '''rcp''', '''rlogin'''), you first must get an authentication ticket. Use the '''kinit''' program to get the ticket. After you've acquired the ticket, you can use the kerberized programs to connect to any kerberized server on the network. You will not be prompted for authentication until your ticket expires (default is one day), unless you specify a different user as a command line argument to the program.
 
−
 
 
−
The kerberized programs will connect to non kerberized daemons, warning you that authentication is not encrypted.
 
−
 
 
−
=== Using Kerberized Server Programs ===
 
−
 
 
−
Using kerberized server programs ('''telnetd''', '''kpropd''', '''klogind''' and '''kshd''') requires two additional configuration steps. First the /etc/services file must be updated to include eklogin and krb5_prop. Second, the inetd.conf or xinetd.conf must be modified for each server that will be activated, usually replacing the server from [[Inetutils]].
 
−
 
 
−
=== Additional Information ===
 
  
−
For additional information consult [http://web.mit.edu/kerberos/www/krb5-1.4/#documentation Documentation for krb-1.4.1] on which the above instructions are based.
+
For additional information, take a look at [http://web.mit.edu/kerberos/www/krb5-1.4/#documentation Documentation for krb-1.4.1].
  
 
= Contents =
 
= Contents =

Revision as of 23:18, 16 December 2006

Download Source: http://web.mit.edu/kerberos/www/dist/krb5/1.7/krb5-1.7-signed.tar

Introduction to MIT Krb5

MIT krb5 is a free implementation of Kerberos 5. Kerberos is a network authentication protocol. It centralizes the authentication database and uses kerberized applications to work with servers or services that support Kerberos allowing single logins and encrypted communication over internal networks or the Internet.

Dependencies

Optional

  • xinetd (services servers only)
  • Linux-Pam (for xdm based logins)
  • OpenLDAP (alternative for krb5kdc password database)
Note:
A time synchronization facility of some sort (like NTP) is needed on your system
if you're going to be using Kerberos. Kerberos won't authenticate if the time
differential between a kerberized client and the KDC server is more than 5 minutes.
And since you'll probably want Kerberos to be able to authenticate, you'll want
to synchronize the time between teh client and the server.

Non-Multilib

Build the packge: 

cd src
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var/lib
   --enable-dns --enable-static --mandir=/usr/share/man
make

Install the package: 

make install
mv -v /usr/lib/libdes425.so.3* /lib
mv -v /usr/lib/libk5crypto.so.3* /lib
mv -v /usr/lib/libkrb5.so.3* /lib
mv -v /usr/lib/libkrb4.so.2* /lib
mv -v /usr/lib/libcom_err.so.3* /lib
mv -v /usr/bin/ksu /bin
ln -v -sf ../../lib/libkrb4.so.2 /usr/lib/libkrb4.so
ln -v -sf ../../lib/libkrb5.so.3 /usr/lib/libkrb5.so
ln -v -sf ../../lib/libk5crypto.so.3 /usr/lib/libk5crypto.so
ln -v -sf ../../lib/libcom_err.so.3 /usr/lib/libcom_err.so
ln -v -sf ../../lib/libdes425.so.3 /usr/lib/libdes425.so
ldconfig

Warning:
login.krb5 does not support shadow passwords. So, when the Kerberos
server is unavailable, the default use of /etc/password will not work
because the passwords are now in /etc/shadow (where they were put while
building CLFS). Entering the following commands without moving the passwords back
to /etc/password could prevent any logins.

If you understand the above warning and Linux-Pam is not installed, the following commands can be used: 

mv -v /bin/login /bin/login.shadow &&
cp -v /usr/sbin/login.krb5 /bin/login

If CrackLib is installed, or if any word list has been put in /usr/share/dict, the following commands should be used: 

ln -s /usr/share/dict/words /var/lib/krb5kdc/kadmin.dict

Command Explanations

--enable-dns: This switch allows realms to be resolved using the DNS server.

--enable-static: This switch builds static libraries in addition to the shared libraries.

mv -v /bin/login /bin/login.shadow && cp -v /usr/sbin/login.krb5 /bin/login && mv -v /usr/bin/ksu /bin: Preserves Shadow's login command, moves ksu and login by moving them to the /bin directory.

mv -v ... /lib and ln -v -sf ...: The login and ksu programs are linked against these libraries, so these libraries are moved to /lib in order to allow logins without mounting /usr.

Multilib

32Bit

TODO....

N32

TODO....

64Bit

TODO....

Configuring

See BLFS' MIT krb5 page for how to configure Kerberos.

For additional information, take a look at Documentation for krb-1.4.1.

Contents

Installed Programs: compile-et, ftp, ftpd, gss-client, gss-server, k5srvutil, kadmin, kadmin.local, kadmind, kadmind4, kdb5_util, kdestroy, kinit, klist, klogind, kpasswd, kprop, kpropd, krb5-send-pr, krb5-config, krb524d, krb524init, krb5kdc, kshd, ksu, ktutil, kvno, login.krb5, rcp, rlogin, rsh, sclient, sim_client, sim_server, sserver, telnet, telnetd, uuclient, uuserver, v5passwd, and v5passwdd
Installed Libraries: libcom_err.{so,a}, libdes425.{so,a}, libgssapi.{so,a}, libgssrpc.{so,a}, libkadm5clnt.{so,a}, libkadm5srv.{so,a}, libkdb5.{so,a}, libkrb5.{so,a}, and libkrb4.{so,a}
Installed Directory: /usr/include/kerberosIV and /var/lib/krb5kdc

Short Descriptions

compile_et converts the table listing error-code names into a C source file.
ftp is a kerberized FTP client.
ftpd is a kerberized FTP daemon.
k5srvutil is a host keytable manipulation utility.
kadmin is an utility used to make modifications to the Kerberos database.
kadmind is a server for administrative access to a Kerberos database.
kdb5_util is the KDC database utility.
kdestroy removes the current set of tickets.
kinit is used to authenticate to the Kerberos server as a principal and acquire a ticket granting ticket that can later be used to obtain tickets for other services.
klist reads and displays the current tickets in the credential cache.
klogind is the server that responds to rlogin requests.
kpasswd is a program for changing Kerberos 5 passwords.
kprop takes a principal database in a specified format and converts it into a stream of database records.
kpropd receives a database sent by kprop and writes it as a local database.
krb5-config gives information on how to link programs against libraries.
krb5kdc is a Kerberos 5 server.
kshd is the server that responds to rsh requests.
ksu is the super user program using Kerberos protocol. Requires a properly configured /etc/shells and ~/.k5login containing principals authorized to become super users.
ktutil is a program for managing Kerberos keytabs.
kvno prints keyversion numbers of Kerberos principals.
login.krb5 is a kerberized login program.
rcp is a kerberized rcp client program.
rlogin is a kerberized rlogin client program.
rsh is a kerberized rsh client program.
telnet is a kerberized telnet client program.
telnetd is a kerberized telnet server.
libcom_err.{so,a} implements the Kerberos library error code.
libgssapi.{so,a} contain the Generic Security Service Application Programming Interface (GSSAPI) functions which provides security services to callers in a generic fashion, supportable with a range of underlying mechanisms and technologies and hence allowing source-level portability of applications to different environments.
libkadm5clnt.{so,a} contains the administrative authentication and password checking functions required by Kerberos 5 client-side programs.
libkadm5srv.{so,a} contain the administrative authentication and password checking functions required by Kerberos 5 servers.
libkdb5.{so,a} is a Kerberos 5 authentication/authorization database access library.
libkrb5.{so,a} is an all-purpose Kerberos 5 library.
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