Differences between revisions 42 and 43
Revision 42 as of 2012-03-04 21:23:23
Size: 15863
Editor: ?Heiko Noordhof
Comment:
Revision 43 as of 2012-03-04 21:53:25
Size: 12317
Editor: ?PaulvanderVlis
Comment:
Deletions are marked like this. Additions are marked like this.
Line 265: Line 265:
# ask for  password: # Ask for password for kerberos LDAP backend
Line 289: Line 289:

kdb5_ldap_util -w "$LDAP_KRBADMIN_PW" \
    -D "cn=krb-admin,$LDAPROOT" \
    stashsrvpw \
    -f /etc/krb5kdc/service.keyfile \
    "cn=krb-admin,$LDAPROOT"

# Setup LDAP structure
# Generate random password for kerberos-admin account in LDAP, and a hash
# from it.
LDAP_KRBADMIN_PW=$(cat /proc/sys/kernel/random/uuid)
echo -n "$LDAP_KRBADMIN_PW" >ldap-krbadmin-pw.txt
chmod 600 ldap-krbadmin-pw.txt
LDAP_KRBADMIN_HASH=$(slappasswd -h '{SHA}' -T ldap-krbadmin-pw.txt)
echo "LDAP Kerberos admin paswoord: "$LDAP_KRBADMIN_PW" >> passwords.txt

cat <<EOF >structure.ldif
dn: cn=krb-admin,${LDAPROOT}
cn: krb-admin
objectClass: organizationalRole
objectClass: simpleSecurityObject
userPassword: ${LDAP_KRBADMIN_HASH}

dn: ou=groups,${LDAPROOT}
objectClass: organizationalUnit
ou: groups

dn: ou=users,${LDAPROOT}
objectClass: organizationalUnit
ou: users
EOF
ldapadd -x -D cn=admin,"${LDAPROOT}" -y ldap-admin-pw.txt -f structure.ldif

# Setup kerberos backend database in LDAP
gunzip -c /usr/share/doc/krb5-kdc-ldap/kerberos.schema.gz >krb.schema
echo 'include krb.schema' >slapd.tmp.conf
slaptest -f slapd.tmp.conf -F ./
mv 'cn=config/cn=schema/cn={0}krb.ldif' krb.schema.ldif
sed -i 's/^dn: cn={0}krb/dn: cn=kerberos,cn=schema,cn=config/' krb.schema.ldif
sed -i 's/^cn: {0}krb/cn: kerberos/' krb.schema.ldif
sed -i '/^structuralObjectClass/,$d' krb.schema.ldif
ldapadd -QY EXTERNAL -H ldapi:/// -f krb.schema.ldif

# Add index
cat <<EOF >krbindex.ldif
dn: olcDatabase={1}hdb,cn=config
add: olcDbIndex
olcDbIndex: krbPrincipalName eq,pres,sub
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f krbindex.ldif

# Add some ACL's
cat <<EOF >krbacl.ldif
dn: olcDatabase={1}hdb,cn=config
replace: olcAccess
olcAccess: to attrs=userPassword,shadowLastChange,krbPrincipalKey by dn="cn=krb-admin,${LDAPROOT}" write by anonymous auth by self write by * none
-
add: olcAccess
olcAccess: to dn.base="" by * read
-
add: olcAccess
olcAccess: to * by dn="cn=krb-admin,${LDAPROOT}" write by * read
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f krbacl.ldif

# Setup MIT-kerberos
cp /etc/krb5.conf /etc/krb5.conf.bak-$(date +%Y%m%d_%H%M)
cat <<EOF >/etc/krb5.conf
[libdefaults]
 default_realm = ${REALM}
 allow_weak_crypto = true
 default_tgs_enctypes = des-cbc-crc
 default_tkt_enctypes = des-cbc-crc
 permitted_enctypes = des-cbc-crc

 krb4_config = /etc/krb.conf
 krb4_realms = /etc/krb.realms
 kdc_timesync = 1
 ccache_type = 4
 forwardable = true
 proxiable = true

[realms]
 ${REALM} = {
  kdc = ${SERVER}
  admin_server = ${SERVER}
  default_domain = ${DOMAIN}
  database_module = openldap_ldapconf
 }

[domain_realm]
 .${DOMAIN} = ${REALM}

[login]
 krb4_convert = true
 krb4_get_tickets = false

[logging]
     kdc = SYSLOG:INFO:DAEMON
     admin_server = SYSLOG:INFO:DAEMON
     default = SYSLOG:INFO:DAEMON

[dbdefaults]
        ldap_kerberos_container_dn = ${LDAPROOT}

[dbmodules]
        openldap_ldapconf = {
                db_library = kldap
                ldap_kdc_dn = "cn=krb-admin,${LDAPROOT}"
                ldap_kadmind_dn = "cn=krb-admin,${LDAPROOT}"
                ldap_service_password_file = /etc/krb5kdc/service.keyfile
                ldap_servers = ldapi:///
                ldap_conns_per_server = 5
EOF

# Stash the LDAP-password for the account the kerberos daemons use to
# read and write to LDAP
echo -e "\nYou will now be asked to enter a password (twice).
Please copy/paste the following password in there: $LDAP_KRBADMIN_PW \n\n"

This will become a setup for NFS4 with Kerberos and secure LDAP on Debian Squeeze (it's not ready at the moment). Kerberos will use LDAP as backend database. Most information in this setup comes from Heiko Noordhof. I know, there are allready pages in this wiki about NFS4, Kerberos and LDAP. This howto tries to give an easy start. This setup is not very secure, but in many cases secure enough.

The idea is, that you copy/paste parts of the howto to your console. Look out when you copy many lines, some commands (like apt-get) will remove later lines from memory.

Server setup:

# become root:
su -

# When you did install LDAP or Kerberos or NFS before, it is a good idea to remove it to
# have a clean start. Backup it first if you want to keep it!
apt-get purge krb5-kdc-ldap gnutls-bin krb5-admin-server nfs-kernel-server \
  ldap-utils slapd krb5-kdc
rm -rv /var/lib/ldap/
rm -rv /etc/ldap/
rm -rv /etc/krb5kdc/
rm -rv /root/kerberos-setup/
rm -r /etc/krb5.keytab
rm -v /etc/krb5.conf
rm -v /etc/ssl/certs/CAself-cert.pem
rm -v /etc/ssl/certs/*_slapd_cert.pem
rm -v /etc/ssl/*.info
rm -v /etc/ssl/private/*_slapd_key.pem
rm -v /etc/ssl/private/CAself-key.pem

# Your fqdn-hostname should be OK, it should be something like:  server1.example.com
# When it's wrong, change your /etc/hosts, there should be a line like:
# 127.0.1.1       server1.example.com   server1
# with this command you can check your fqdn hostname:
hostname --fqdn

# Main setup variables defaults
SERVER=$(hostname --fqdn)   # something like: server1.example.com
DOMAIN=${SERVER#*.}         # something like: example.com
REALM=$(echo "${DOMAIN}" | tr '[:lower:]' '[:upper:]')   # something like: EXAMPLE.COM
LDAPROOT=""; IFS="."; for DC in $DOMAIN ; do LDAPROOT="${LDAPROOT},dc=$DC"; done
LDAPROOT="${LDAPROOT#,}"    # somthing like "dc=example,dc=com"
echo -e "\nSERVER:   $SERVER \nDOMAIN:   $DOMAIN \nREALM:    $REALM \nLDAPROOT: $LDAPROOT \n\
Change this defaults when needed with something like: DOMAIN='example2.com' \n"

# Install packages without questions. You can also answer the questions but this is
# pointless, because the configuration will be overwritten later.
# Some errors are normal because of the noninteractive install
DEBIAN_FRONTEND=noninteractive apt-get install ldap-utils slapd nfs-kernel-server \
  krb5-admin-server krb5-kdc krb5-kdc-ldap krb5-doc libnss-ldap nscd libpam-ldap \
  gnutls-bin ssl-cert ntp pwgen

# Directory for temporary setup files
SETUPDIR=/root/kerberos-setup/
mkdir "$SETUPDIR"
chmod 700 "$SETUPDIR"
cd "$SETUPDIR"

# Setup ldap.conf for clients
cat <<EOF >/etc/ldap/ldap.conf
BASE    ${LDAPROOT}
URI     ldapi://
EOF

# Setup SSL/TLS certificate (self-signed) for TLS on LDAP
CA_KEY=/etc/ssl/private/CAself-key.pem
CA_INFO=/etc/ssl/CAself.info
CA_CERT=/etc/ssl/certs/CAself-cert.pem
certtool --generate-privkey >"${CA_KEY}"
cat <<EOF >"${CA_INFO}"
cn = ${DOMAIN}
ca
cert_signing_key
EOF
certtool \
    --generate-self-signed \
    --load-privkey "${CA_KEY}" \
    --template "${CA_INFO}" \
    --outfile "${CA_CERT}"
chgrp ssl-cert "${CA_KEY}"
chmod 0640 "${CA_KEY}"

# Generate private-key for TLS on the LDAP-service
LDAP_TLS_KEY="/etc/ssl/private/${SERVER}_slapd_key.pem"
LDAP_TLS_INFO="/etc/ssl/${SERVER}.info"
LDAP_TLS_CERT="/etc/ssl/certs/${SERVER}_slapd_cert.pem"
certtool --generate-privkey >"${LDAP_TLS_KEY}"
cat <<EOF >"${LDAP_TLS_INFO}"
organization = ${DOMAIN}
cn = ${SERVER}
tls_www_server
encryption_key
signing_key
EOF
certtool \
    --generate-certificate \
    --load-privkey "${LDAP_TLS_KEY}" \
    --load-ca-certificate "${CA_CERT}" \
    --load-ca-privkey "${CA_KEY}" \
    --template "${LDAP_TLS_INFO}" \
    --outfile "${LDAP_TLS_CERT}"
chgrp ssl-cert "${LDAP_TLS_KEY}"
chmod 0640 "${LDAP_TLS_KEY}"

# Set access to ssl keys for LDAP-daemon (slapd)
adduser openldap ssl-cert

# Generate hash from admin password
LDAP_ADMIN_PW=$(pwgen -s 10 1)
echo -n "$LDAP_ADMIN_PW" >ldap-admin-pw.txt
chmod 600 ldap-admin-pw.txt
LDAP_ADMIN_HASH=$(slappasswd -h '{SHA}' -T ldap-admin-pw.txt)
touch passwords.txt; chmod 600 passwords.txt
echo -n "LDAP admin password: $LDAP_ADMIN_PW" >> passwords.txt

# Create ldifs and load them into LDAP
cat <<EOF >slapd-loglevel.ldif
dn: cn=config
changeType: modify
replace: olcLogLevel
olcLogLevel: stats
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f slapd-loglevel.ldif

cat <<EOF >slapd-tls.ldif
dn: cn=config
changeType: modify
add: olcTLSCACertificateFile
olcTLSCACertificateFile: ${CA_CERT}
-
add: olcTLSCertificateFile
olcTLSCertificateFile: ${LDAP_TLS_CERT}
-
add: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: ${LDAP_TLS_KEY}
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f slapd-tls.ldif

cat <<EOF >slapd-database.ldif
dn: olcDatabase={1}hdb,cn=config
changeType: modify
replace: olcDbConfig
olcDbConfig: {0}set_cachesize 0 2097152 0
olcDbConfig: {1}set_lk_max_objects 1500
olcDbConfig: {2}set_lk_max_locks 1500
olcDbConfig: {3}set_lk_max_lockers 1500
olcDbConfig: {4}set_flags DB_LOG_AUTOREMOVE
-
replace: olcRootPW
olcRootPW: ${LDAP_ADMIN_HASH}
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f slapd-database.ldif

# Do not listen on the clear-text port (389) only SSL/LDAPS (636)
sed -i 's|^SLAPD_SERVICES.*|SLAPD_SERVICES="ldaps:/// ldapi:///"|' /etc/default/slapd

# Restart LDAP-server
/etc/init.d/slapd restart

# Setup LDAP structure
# Generate random password for kerberos-admin account in LDAP, and a hash.
LDAP_KRBADMIN_PW=$(pwgen -s 12 1)
echo -n "$LDAP_KRBADMIN_PW" >ldap-krbadmin-pw.txt
chmod 600 ldap-krbadmin-pw.txt
LDAP_KRBADMIN_HASH=$(slappasswd -h '{SHA}' -T ldap-krbadmin-pw.txt)

cat <<EOF >structure.ldif
dn: cn=krb-admin,${LDAPROOT}
cn: krb-admin
objectClass: organizationalRole
objectClass: simpleSecurityObject
userPassword: ${LDAP_KRBADMIN_HASH}

dn: ou=groups,${LDAPROOT}
objectClass: organizationalUnit
ou: groups

dn: ou=users,${LDAPROOT}
objectClass: organizationalUnit
ou: users
EOF
ldapadd -x -D cn=admin,"${LDAPROOT}" -y ldap-admin-pw.txt -f structure.ldif

# Setup kerberos services, with backend database in LDAP
gunzip -c /usr/share/doc/krb5-kdc-ldap/kerberos.schema.gz >krb.schema
echo 'include krb.schema' >slapd.tmp.conf
slaptest -f slapd.tmp.conf -F ./
mv  'cn=config/cn=schema/cn={0}krb.ldif' krb.schema.ldif
sed -i 's/^dn: cn={0}krb/dn: cn=kerberos,cn=schema,cn=config/' krb.schema.ldif
sed -i 's/^cn: {0}krb/cn: kerberos/' krb.schema.ldif
sed -i '/^structuralObjectClass/,$d' krb.schema.ldif
ldapadd -QY EXTERNAL -H ldapi:///  -f krb.schema.ldif

# Add index
cat <<EOF >krbindex.ldif
dn: olcDatabase={1}hdb,cn=config
add: olcDbIndex
olcDbIndex: krbPrincipalName eq,pres,sub
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f krbindex.ldif

# Add some ACL's
cat <<EOF >krbacl.ldif
dn: olcDatabase={1}hdb,cn=config
replace: olcAccess
olcAccess: to attrs=userPassword,shadowLastChange,krbPrincipalKey by dn="cn=krb-admin,${LDAPROOT}" write by anonymous auth by self write by * none
-
add: olcAccess
olcAccess: to dn.base="" by * read
-
add: olcAccess
olcAccess: to * by dn="cn=krb-admin,${LDAPROOT}" write by * read
EOF
ldapmodify -v -Y EXTERNAL -H ldapi:/// -f krbacl.ldif

# Setup MIT-kerberos
cp /etc/krb5.conf /etc/krb5.conf.bak-$(date +%Y%m%d_%H%M)
cat <<EOF >/etc/krb5.conf
[libdefaults]
        default_realm = ${REALM}
        allow_weak_crypto = true
        default_tgs_enctypes = des-cbc-crc
        default_tkt_enctypes = des-cbc-crc
        permitted_enctypes = des-cbc-crc

        krb4_config = /etc/krb.conf
        krb4_realms = /etc/krb.realms
        kdc_timesync = 1
        ccache_type = 4
        forwardable = true
        proxiable = true

[realms]
        ${REALM} = {
                kdc = ${SERVER}
                admin_server = ${SERVER}
                default_domain = ${DOMAIN}
                database_module = openldap_ldapconf
        }

[domain_realm]
        .${DOMAIN} = ${REALM}

[login]
        krb4_convert = true
        krb4_get_tickets = false

[logging]
     kdc = SYSLOG:INFO:DAEMON
     admin_server = SYSLOG:INFO:DAEMON
     default = SYSLOG:INFO:DAEMON

[dbdefaults]
        ldap_kerberos_container_dn = ${LDAPROOT}

[dbmodules]
        openldap_ldapconf = {
                db_library = kldap
                ldap_kdc_dn = "cn=krb-admin,${LDAPROOT}"
                ldap_kadmind_dn = "cn=krb-admin,${LDAPROOT}"
                ldap_service_password_file = /etc/krb5kdc/service.keyfile
                ldap_servers = ldapi:///
                ldap_conns_per_server = 5
EOF

# ACL to grant all permissions to principals like "<name>/admin@<REALM>"
echo '*/admin *' >>/etc/krb5kdc/kadm5.acl

# Ask for password for kerberos LDAP backend
KLDAPPWD=`pwgen -s 10 1`
read -p "Password for Kerberos LDAP backend, specify a password (return='$KLDAPPWD') : " KLDAPPW
if test "$KLDAPPW" = ""; then
  KLDAPPW="$KLDAPPWD"
fi
echo $KLDAPPWD > $SETUPDIR/kerberos-ldap-password.txt

# Create basic entries in the kerberos LDAP backend
echo -e "You will now be asked to enter the password (twice). \n
Please copy and paste the password, it is: $KLDAPPWD\n"

kdb5_ldap_util -w "$LDAP_KRBADMIN_PW" \
    -D  "cn=krb-admin,$LDAPROOT" \
    create \
    -subtrees "$LDAPROOT" \
    -r "$REALM" \
    -s \
    -H ldapi:///

# Stash the LDAP-password for the account the kerberos daemons use to
# read and write to LDAP
echo -e "You will now be asked to enter another password (twice). \n
Please copy/paste the following password in there:  $LDAP_KRBADMIN_PW\n"

kdb5_ldap_util -w "$LDAP_KRBADMIN_PW" \
    -D  "cn=krb-admin,$LDAPROOT" \
    stashsrvpw \
    -f /etc/krb5kdc/service.keyfile \
    "cn=krb-admin,$LDAPROOT"

# Restart the Kerberos daemons
/etc/init.d/krb5-kdc restart  
/etc/init.d/krb5-admin-server restart

# kerberos admin user:
read -p "Kerberos admin username, normally your name (without "/admin"): " KADMIN
echo "kerberos admin username: $KADMIN/admin" >> passwords.txt
KADMINPWD=`pwgen -s 10 1`
read -p "Password for Kerberos admin user, specify a password (return='$KADMINPWD') : " KADMINPW
if test "$KADMINPW" = ""; then; KADMINPW="$KADMINPWD"; fi
echo "kerberos admin paswword: $KADMINPW >> passwords.txt
kadmin.local -q "addprinc -pw $KADMINPW $KADMIN/admin"

# The NFS-server must know the same user names and UID's as the clients.
# Therefore our server name service switch needs to be a client of the server itself.
cp /etc/libnss-ldap.conf /etc/libnss-ldap.conf -$(date +%Y%m%d_%H%M)
cat <<EOF >/etc/libnss-ldap.conf
uri ldapi://uri ldapi://
ldap_version 3
base ${LDAPROOT}
scope sub
EOF

# Activate LDAP in name service switch
sed -i 's/compat/files ldap/' /etc/nsswitch.conf
/etc/init.d/nscd restart

# Setup NFS4-service
# ==> Security level "krb5i" is middle level. More secure (everything encrypted)
# would be: "krb5p". This must match mount option on the client.
mkdir -p /srv/nfs4/home
echo "/srv/nfs4 gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check) " >> /etc/exports
echo "/srv/nfs4/home gss/krb5i(rw,sync,no_subtree_check) " >> /etc/exports

# Create kerberos principal for NFS-server
kadmin.local -q "addprinc -randkey nfs/${SERVER}"

# Store the key for the nfs-service principal in (default) keytab file
kadmin.local -q "ktadd nfs/${SERVER}"

# Configure NFS-service daemons for kerberized NFS4:
sed -i 's/^ *NEED_SVCGSSD=.*$/NEED_SVCGSSD=yes/' /etc/default/nfs-kernel-server
sed -i 's/^ *NEED_IDMAPD=.*$/NEED_IDMAPD=yes/' /etc/default/nfs-common

# Restart the NFS4 (related) services
/etc/init.d/nfs-kernel-server stop
/etc/init.d/nfs-common restart
/etc/init.d/nfs-kernel-server start

echo -e "\nSave this information on a good place:\n\n
==> LDAP root:                ${LDAPROOT} \n
==> LDAP super-user account:  cn=admin,${LDAPROOT} \n
==> LDAP super-user password: ${LDAP_ADMIN_PW} \n
==> Kerberos realm:           ${REALM} \n
==> Kerberos LDAP password:   $KLDAPPWD \n
==> Kerberos admin username:  $KADMIN/admin \n
==> Kerberos admin paswword:  $KADMINPW \n"

The setupdir contains all passwords among other things. Please make sure to remove this directory later.

You can find some useful scripts to handle users here: http://www.vandervlis.nl/krb5/

Add the moment the setup for the client is still missing here...