| Machines | Port | Protocol | Reason |
| Ltnb0 | 20, 21 | TCP | Ftp access to ltnb by external entities (for updating Web pages for example) |
| Ltnb0, Ltnb10 | 22 | TCP | Ssh (remote access) |
| Ltnb0, Ltnb10 | 25 | TCP | Incoming mail |
| Ltnb10 | 53 | TCP & UDP | Domain lookups for .ltnb.lu domains by external entities |
| Ltnb0 | 80 | TCP | Web hosting |
| Ltnb0 | 123 | TCP & UDP | Xntp (time keeping) |
| Ltnb0 | 143 | TCP | Imap (mail) browsing from outside |
| Ltnb0 | 443 | TCP | Https web hosting |