SqueezeKerberosNFSv4StrongCrypto

How to install NFSv4 with strong crypto and Kerberos authentication on Debian Squeeze (using some packages of unstable)

Server

Packages

unstable packages

• linux-image-2.6 >= 2.6.35
• version nfs-common >= 1.2.3
• rpcbind instead of portmap (see debian bug #620059)

kdc:~# apt-get install -t linux-image-2.6
kdc:~# reboot

kdc:~# apt-get install rpcbind # replace portmap by rpcbind in initscripts or install rpcbind >= 0.2.0-5 (see debian bug #565201)

kdc:~# apt-get install -t unstable nfs-kernel-server nfs-common libtirpc1

Configuration

/etc/default/nfs-common

[...]
# Do you want to start the idmapd daemon? It is only needed for NFSv4.
NEED_IDMAPD=yes

# Do you want to start the gssd daemon? It is required for Kerberos mounts.
NEED_GSSD=yes

/etc/default/nfs-kernel-server

NEED_SVCGSSD=yes

/etc/krb5kdc/kdc.conf

` supported_enctypes` must only contains encryption types which are not weak (see weak encryption types)

[kdcdefaults]
    kdc_ports = 750,88
    kdc_tcp_ports = 750,88

[realms]
    COINCOIN.EU = {
        database_name = /var/lib/krb5kdc/principal
        admin_keytab = FILE:/etc/krb5kdc/kadm5.keytab
        acl_file = /etc/krb5kdc/kadm5.acl
        key_stash_file = /etc/krb5kdc/stash
        kdc_ports = 750,88
        max_life = 10h 0m 0s
        max_renewable_life = 7d 0h 0m 0s
        master_key_type = des3-hmac-sha1
        supported_enctypes = aes256-cts:normal arcfour-hmac:normal des3-hmac-sha1:normal
        default_principal_flags = +preauth
    }

/etc/krb5.conf

[libdefaults]
        default_realm = COINCOIN.EU

Create needed directory

kdc:/root# mkdir /mnt/sdb1
kdc:/root# mkdir -p /export/Documents

/etc/exports

/export gss/krb5p(rw,async,no_subtree_check,crossmnt,fsid=0)
/export/Documents  gss/krb5p(rw,async,no_subtree_check)

/etc/fstab

# [...]
/dev/sdb1           /mnt/sdb1         ext3 defaults,acl 1       2
/mnt/sdb1/Documents /export/Documents none ro,bind      0       0

mount directory

kdc:/root# mount /mnt/sdb1
kdc:/root# mount /export/Documents

Export directories

kdc:/root# exportfs -rv
exporting gss/krb5p:/export/Documents
exporting gss/krb5p:/export

NFS service: Create principal entry

kdc:/root# kadmin.local
Authenticating as principal root/admin@COINCOIN.EU with password.
kadmin:  addprinc -randkey nfs/kdc.coincoin.eu
WARNING: no policy specified for nfs/kdc.coincoin.eu@COINCOIN.EU; defaulting to no policy
Principal "nfs/kdc.coincoin.eu@COINCOIN.EU" created.

Check that weak encryption types are not allowed with `getprinc nfs/kdc.coincoin.eu`.

export nfs@kdc principal to the keytab

kdc:/root# kadmin.local
Authenticating as principal root/admin@COINCOIN.EU with password.
ktadd -k /etc/krb5.keytab nfs/kdc.coincoin.eu

You can list content of keytab:

kdc:~# ktutil 
ktutil:  rkt /etc/krb5.keytab 
ktutil:  list
slot KVNO Principal
---- ---- ---------------------------------------------------------------------
   1    2    nfs/kdc.coincoin.eu@COINCOIN.EU

You should check that weak encryption types are not enabled with `list -e`.

Create client entry

kdc:/root# kadmin.local
kadmin:  addprinc -randkey nfs/client.coincoin.eu
WARNING: no policy specified for nfs/client.coincoin.eu@COINCOIN.EU; defaulting to no policy
Principal "nfs/client.coincoin.eu@COINCOIN.EU" created.

Start services

• /etc/init.d/nfs-common start
• /etc/init.d/nfs-kernel-server start

Client

Packages

• linux-image-2.6 >= 2.6.35
• version nfs-common >= 1.2.3

client:~# apt-get install -t linux-image-2.6
client:~# reboot

client:~# apt-get install -t unstable nfs-client

Configuration

/etc/krb5.conf

[libdefaults]
        default_realm = COINCOIN.EU

/etc/fstab

kdc.coincoin.eu:/Documents /mnt/Documents nfs4 sec=krb5p,rw,hard,rsize=32768,wsize=32768,noexec,nosuid,auto 0  0

Check DNS configuration

root@client:/root# host kdc.coincoin.eu
kdc.coincoin.eu has address 192.168.20.123
root@client:/root# host 192.168.20.123
123.20.168.192.in-addr.arpa domain name pointer kdc.coincoin.eu.

/etc/default/nfs-common

[...]
# Do you want to start the idmapd daemon? It is only needed for NFSv4.
NEED_IDMAPD=yes

# Do you want to start the gssd daemon? It is required for Kerberos mounts.
NEED_GSSD=yes

Start services

client:~# /etc/init.d/nfs-common restart

Create keytab

client:~# kadmin -p superuser
Authenticating as principal superuser with password.
Password for superuser@COINCOIN.EU: 
ktadd -k /etc/krb5.keytab nfs/client.coincoin.eu

Check configuration

See KerberosNFSv4#Errors

verify enctypes

klist -e
Ticket cache: FILE:/tmp/krb5cc_1000_6gVtAq
Default principal: plop@COINCOIN.EU

Valid starting     Expires            Service principal
03/30/11 18:32:59  03/31/11 04:32:59  krbtgt/COINCOIN.EU@COINCOIN.EU
        renew until 03/31/11 18:34:25, Etype (skey, tkt): aes256-cts-hmac-sha1-96, aes256-cts-hmac-sha1-96 
03/30/11 21:31:05  03/31/11 04:32:59  nfs/kdc.coincoin.eu@COINCOIN.EU
        renew until 03/31/11 18:34:25, Etype (skey, tkt): aes256-cts-hmac-sha1-96, aes256-cts-hmac-sha1-96