Comment 15 for bug 891825

First of all its NFS3 for sure, if I put nfsvers=4 parameter and try to mount -a I get:

mount.nfs: mounting ubuntuserver:/media/huge failed, reason given by server:
  No such file or directory
mount.nfs: mounting ubuntuserver:/media/externi-disk failed, reason given by server:
  No such file or directory

It's not firewall.
Mine server is on 192.168.0.1, and client is 192.168.0.2.
Here is an ufw rule:
sudo ufw status:
...

To Action From
-- ------ ----
Anywhere ALLOW 192.168.0.2

Next I did a zenmap port scan, from client to server, here you are:

PORT STATE SERVICE VERSION
21/tcp open ftp vsftpd 2.2.2
22/tcp open ssh OpenSSH 5.3p1 Debian 3ubuntu7 (protocol 2.0)
| ssh-hostkey: blabla (DSA)
|_2048 blabla (RSA)
80/tcp open http Apache httpd 2.2.14 ((Ubuntu))
|_html-title: Site doesn't have a title (text/html).
111/tcp open rpcbind
| rpcinfo:
| 100000 2 111/udp rpcbind
| 100003 2,3,4 2049/udp nfs
| 100021 1,3,4 33800/udp nlockmgr
| 100005 1,2,3 50000/udp mountd
| 100024 1 50001/udp status
| 100000 2 111/tcp rpcbind
| 100003 2,3,4 2049/tcp nfs
| 100021 1,3,4 38914/tcp nlockmgr
| 100005 1,2,3 50000/tcp mountd
|_100024 1 50001/tcp status
2049/tcp open rpcbind
3128/tcp open http-proxy Squid webproxy 3.0.STABLE19
| http-open-proxy: Potentially OPEN proxy.
|_Methods supported: GET HEAD
3389/tcp open microsoft-rdp VirtualBox VM Remote Desktop Service
3390/tcp open microsoft-rdp VirtualBox VM Remote Desktop Service
8000/tcp open ssl/http TwistedWeb httpd 8.1.0 (Twisted 9.0.0)
|_html-title: Sign in -- Sage
9091/tcp open http Transmission BitTorrent management httpd (unauthorized)
|_html-title: Site doesn't have a title (text/html; charset=ISO-8859-1).
| http-auth: HTTP Service requires authentication
|_ Auth type: Basic, realm = Transmission
50000/tcp open rpcbind
50001/tcp open rpcbind

As you can see everything is open, ports 50000 and 50001 on server are the ones for NFS.
I've also added on server hosts.allow: ALL: 192.168.0.2, and on client ALL: 192.168.0.1

On every other version of ubuntu this worked fine, and I haven't been changing any configuration on server.