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Code42 Support

Networking Between Computers: Ports, UPnP, And Nat-PMP

Applies to:
  • CrashPlan for Home


CrashPlan actively communicates between a social network of computers using various networking technologies. This article explains how these technologies are used by CrashPlan.

Computer-To-Computer Connections

CrashPlan uses Universal Plug and Play (UPnP) and NAT Port Mapping Protocol (Nat-PMP) for computer-to-computer communication. Even if you only back up to CrashPlan Central, your computers talk to each other. This happens for reporting purposes or to register setting changes.

UPnP (Windows)

CrashPlan uses UPnP for computer-to-computer connections so that computers can establish direct connection to each other without complex setup. UPnP is a set of networking protocols that lets networked devices, like computers, see each other on a network and create network services for data sharing and communication.


Similar to UPnP, CrashPlan uses NAT-PMP to establish a connection between computers on an account or between Friends. A computer within a private network relies on NAT-PMP to automatically configure the router so that computers outside the network can contact it.


The CrashPlan app requires the following ports to communicate with your backup destinations. Depending on the destinations you use, you may not require all ports:

Port(s) Protocol Destination Description
4242* TCP CrashPlan device (Default) Listening port required for computer-to-computer connections
Port can be changed from Settings > General > Inbound backup from other computers
4243* TCP localhost (Default) Used by the CrashPlan app to connect to the CrashPlan service
443 TCP Code42 cloud (Required) Used by the CrashPlan app to connect to the Code42 cloud

1,024 - 14500,

49,000 - 52,000

TCP CrashPlan device

(Optional) NAT traversal ranges used for connecting between computers





CrashPlan device (Optional) Standard UPnP ports required for computer-to-computer connections
5351 UDP CrashPlan device (Optional) Standard NAT-PMP port required for computer-to-computer connections

* Depending on your configuration, alternative ports may be used. To find the ports used on your computer, identify the ports used by the CrashPlan app.

Disabling UPnP or NAT-PMP
If you choose to disable UPnP or NAT-PMP on your router, you must configure port forwarding to allow computer-to-computer backup.