no era un problema di configurazione di apache, come sospettavo... in particolare non riesco a far funzionare mod_mono_auto
così ho dovuto configurarlo a mano (ossia uso mod_mono)
codice:
<VirtualHost *:80>
ServerName local.mono
DocumentRoot /home/nexus6/www/mono/
AddType application/x-asp-net .aspx
AddType application/x-asp-net .asmx
AddType application/x-asp-net .ashx
AddType application/x-asp-net .asax
AddType application/x-asp-net .ascx
AddType application/x-asp-net .soap
AddType application/x-asp-net .rem
AddType application/x-asp-net .axd
AddType application/x-asp-net .cs
AddType application/x-asp-net .config
AddType application/x-asp-net .Config
AddType application/x-asp-net .dll
DirectoryIndex index.aspx
DirectoryIndex Default.aspx
DirectoryIndex default.aspx
MonoAutoApplication disabled
AddHandler mono .aspx .ascx .asax .ashx .config .cs .asmx .axd
MonoApplications "/:/home/nexus6/www/mono"
<Directory /home/nexus6/www/mono/>
Options Indexes FollowSymLinks MultiViews
AllowOverride All
Order allow,deny
Allow from all
SetHandler mono
</Directory>
</VirtualHost>