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(Requirements)
(Requirements)
 
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==== Kerberos and NFS ====
==== Kerberos and NFS ====
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Kerberos can be used to provide both '''mutual authentication''' (validating both the client and server prior to transmitting data) and encryption for data sent via NFS.  This is implemented with the '''RPCSEC_GSS''' security flavor of ONC RPC protocol, defined by RFC 1831 and RFC 2203.  This subsection of [[NFS_Howto_Security|NFS Howto: Security]]  attempts to provide a complete and accurate cookbook configuration guide for how to get Kerberos validation / authentication working with NFSv3/NFSv4 mount points.
+
Kerberos can be used to provide both '''mutual authentication''' (validating both the client and server prior to transmitting data) and encryption for data sent via NFS.  This is implemented with the '''RPCSEC_GSS''' security flavor of ONC RPC protocol, defined by RFC 1831 and RFC 2203.  This sub-section of [[NFS_Howto_Security|NFS Howto: Security]]  attempts to provide a complete and accurate cookbook configuration guide for how to get Kerberos validation / authentication working with NFSv3/NFSv4 mount points.
===== Requirements =====
===== Requirements =====
*''/etc/services'' should have entries in it for port '''2049''' for both TCP and UDP NFS.  This should be present in virtually every modern version of Linux, but it warrants mentioning.
*''/etc/services'' should have entries in it for port '''2049''' for both TCP and UDP NFS.  This should be present in virtually every modern version of Linux, but it warrants mentioning.
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# that require network functionality will fail.
# that require network functionality will fail.
127.0.0.1              localhost.localdomain localhost
127.0.0.1              localhost.localdomain localhost
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10.161.131.10      client.netapp.com client
+
10.161.131.10      client.sourceforge.net client
</pre>
</pre>
Is ok.  Whereas this:
Is ok.  Whereas this:
<pre>
<pre>
-
[cmsmith@broken ~]$ cat /etc/hosts
+
[cmsmith@client ~]$ cat /etc/hosts
# Do not remove the following line, or various programs
# Do not remove the following line, or various programs
# that require network functionality will fail.
# that require network functionality will fail.
-
127.0.0.1              localhost.localdomain broken localhost  
+
127.0.0.1              localhost.localdomain client localhost  
</pre>
</pre>
is not.
is not.
===== Kerberos Configuration =====
===== Kerberos Configuration =====
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+
To use Kerberized NFS, we need to add the following into ''/etc/sysconfig/nfs'' to start the necessary additional daemons on the client:
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'''Verify that the client has a working Kerberos configuration'''<br/>
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<pre>
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'''Generate NFS Machine Credentials for the Kerberos Client<br/>
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# echo "SECURE_NFS=YES" >> /etc/sysconfig/nfs
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'''Add the NFS Machine Credentials to both the Kerberos Client and Server'''<br/>
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</pre>
 +
Next, create an NFS principal for the host(s) that will be involved in NFS transactions.  This means that ''both'' the NFS server and the NFS client need to have a special principal in place.  Create them as follows:
 +
<pre>
 +
# kadmin
 +
Authenticating as principal root/admin@SOURCEFORGE.NET with password.
 +
Password for root/admin@SOURCEFORGE.NET:
 +
kadmin: addprinc -randkey nfs/client.sourceforge.net
 +
WARNING: no policy specified for nfs/client.sourceforge.net@SOURCEFORGE.NET; defaulting to no policy
 +
Principal "nfs/client.sourceforge.net@SOURCEFORGE.COM" created.
 +
</pre>
 +
On each of the clients, download the necessary principals to the local keytab file using '''ktadd'''.  As an example, for the NFS client secondus.rdu.kronos.net would require you to run:
 +
<pre>
 +
# kadmin
 +
kadmin: ktadd nfs/client.sourceforge.net
 +
Entry for principal nfs/client.sourceforge.net with kvno 4, encryption type DES cbc mode with CRC-32
 +
added to keytab WRFILE:/etc/krb5.keytab.
 +
</pre>
===== NFSv3 Specifics =====
===== NFSv3 Specifics =====
===== NFSv4 Specifics =====
===== NFSv4 Specifics =====
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-
 
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The following is only necessary if you wish to use Kerberos 5 (krb5). (Which is a good idea.)
 
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We assume you have a Kerberos KDC installed somewhere and have configured Kerberos on your client and server.
 
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Create machine credentials for the client. This means creating a Kerberos V5 principal/instance name of the form nfs/dns.name.of.client@REALM, and either adding a key for this principal to an existing /etc/krb5.keytab or creating an /etc/krb5.keytab.
 
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Note: only the encryption type of des-cbc-crc is functional so far in the kernel, so add only this type of key.
 
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kadmin: addprinc -randkey nfs/myclient.mydomain
 
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kadmin: ktadd -e des-cbc-crc:normal -k /tmp/keytab nfs/myclient.mydomain
 
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Now copy the new keytab /tmp/keytab to /etc/krb5.keytab on the client.
 
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Repeat steps 2 and 3 for the server, this time adding a key for nfs/dns.name.of.server@REALM to the keytab on the server.
 
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Things to be aware of when using Kerberos:
 
==== SPKM and NFS ====
==== SPKM and NFS ====

Latest revision as of 16:36, 11 April 2006

Contents

Kerberos and NFS

Kerberos can be used to provide both mutual authentication (validating both the client and server prior to transmitting data) and encryption for data sent via NFS. This is implemented with the RPCSEC_GSS security flavor of ONC RPC protocol, defined by RFC 1831 and RFC 2203. This sub-section of NFS Howto: Security attempts to provide a complete and accurate cookbook configuration guide for how to get Kerberos validation / authentication working with NFSv3/NFSv4 mount points.

Requirements
  • /etc/services should have entries in it for port 2049 for both TCP and UDP NFS. This should be present in virtually every modern version of Linux, but it warrants mentioning.
  • A working Kerberos realm for all of your NFS clients and server to authenticate against.
  • A working NTP configuration on all hosts participating in your Kerberos realm. This will insure that the system clocks on your machines are set to matching times.
  • Proper forward/reverse name FQDN/IP resolution must be working in DNS, or, at a minimum, the /etc/hosts file must contain this information. The machine's hostname must also not be included on the localhost line, aka:
[cmsmith@client ~]$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               localhost.localdomain localhost
10.161.131.10       client.sourceforge.net client

Is ok. Whereas this:

[cmsmith@client ~]$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               localhost.localdomain client localhost 

is not.

Kerberos Configuration

To use Kerberized NFS, we need to add the following into /etc/sysconfig/nfs to start the necessary additional daemons on the client:

# echo "SECURE_NFS=YES" >> /etc/sysconfig/nfs

Next, create an NFS principal for the host(s) that will be involved in NFS transactions. This means that both the NFS server and the NFS client need to have a special principal in place. Create them as follows:

# kadmin
Authenticating as principal root/admin@SOURCEFORGE.NET with password.
Password for root/admin@SOURCEFORGE.NET: 
kadmin: addprinc -randkey nfs/client.sourceforge.net
WARNING: no policy specified for nfs/client.sourceforge.net@SOURCEFORGE.NET; defaulting to no policy
Principal "nfs/client.sourceforge.net@SOURCEFORGE.COM" created.

On each of the clients, download the necessary principals to the local keytab file using ktadd. As an example, for the NFS client secondus.rdu.kronos.net would require you to run:

# kadmin
kadmin: ktadd nfs/client.sourceforge.net
Entry for principal nfs/client.sourceforge.net with kvno 4, encryption type DES cbc mode with CRC-32 
added to keytab WRFILE:/etc/krb5.keytab.
NFSv3 Specifics
NFSv4 Specifics

SPKM and NFS

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