Puertos 21000–21999
| Port | Protocolo | Servicio | Descripción (IANA) |
|---|---|---|---|
| 21000 | TCP, UDP | irtrans | IRTrans Control |
| 21010 | TCP, UDP | notezilla-lan | Notezilla.Lan Server |
| 21212 | TCP, UDP | trinket-agent | Distributed artificial intelligence |
| 21213 | TCP, UDP | cohesity-agent | Cohesity backup agents |
| 21221 | TCP, UDP | aigairserver | Services for Air Server |
| 21337 | TCP, UDP | xahaud | Xahau P2P network protocol |
| 21553 | TCP, UDP | rdm-tfs | Raima RDM TFS |
| 21554 | TCP, UDP | dfserver | MineScape Design File Server |
| 21590 | TCP, UDP | vofr-gateway | VoFR Gateway |
| 21800 | TCP, UDP | tvpm | TVNC Pro Multiplexing |
| 21801 | TCP | sal | Safe AutoLogon |
| 21845 | TCP, UDP | webphone | webphone |
| 21846 | TCP, UDP | netspeak-is | NetSpeak Corp. Directory Services |
| 21847 | TCP, UDP | netspeak-cs | NetSpeak Corp. Connection Services |
| 21848 | TCP, UDP | netspeak-acd | NetSpeak Corp. Automatic Call Distribution |
| 21849 | TCP, UDP | netspeak-cps | NetSpeak Corp. Credit Processing System |