Port 17500Dropbox LAN Sync
Dropbox LAN Sync utilizes TCP and UDP port 17500 to efficiently synchronize files between Dropbox clients on the same local network, enabling accelerated file sharing without relying solely on internet connectivity..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 43,713
2 transports registered
payload readable on path
registered with iana
caution
rank 27 of 993 · top 3%
Technical Details
what runs on :17500Dropbox LAN Sync is a feature integrated into the Dropbox client application that optimizes file synchronization within a local network environment. This mechanism helps reduce external bandwidth consumption by transferring files directly between devices connected to the same network.
The protocol employs UDP port 17500 initially for discovery purposes. When a Dropbox client is active, it sends broadcast packets to the local subnet over UDP. Other Dropbox clients listening on the same port receive these packets and, if associated with the same account, acknowledge their presence. This mutual awareness facilitates the direct exchange of files.
Following the discovery process, Dropbox clients establish TCP sessions over port 17500 to handle the actual file transfers. This direct connection method ensures higher data integrity, reliability, and faster synchronization compared to routing data solely through Dropbox's cloud servers. By offloading local file transfers to the LAN, Dropbox LAN Sync enhances performance and efficiency for collaborative, multi-device Dropbox users.
Security Information
exposure of :17500risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
file transfer averages 4.1 across 114 ports — this one sits 0.1 below.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
official
registered with iana for this service — scanners fingerprint it by number
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
From a security perspective, open exposure of UDP discovery broadcasts on port 17500 may leak information about Dropbox clients present within the network, potentially assisting an attacker in network reconnaissance or lateral movement.
Common vulnerabilities include:
- Unauthorized access if network segmentation is inadequate
- Potential data interception during file transfer due to unencrypted communication (when encryption is not enabled)
- Misconfigured firewalls allowing unwanted inbound/outbound traffic on port 17500
Mitigations typically involve:
- Restricting UDP broadcasts and TCP connections to trusted segments or hosts
- Employing firewalls to limit access strictly within organizational boundaries
- Using strong peer authentication within the Dropbox ecosystem
- Enabling encryption features when available or utilizing VPN tunnels to secure inter-client communications
- Network monitoring to identify anomalous Dropbox LAN Sync activity that could indicate misuse or compromise
Related Ports
the 8 most looked-up other ports in file transfer — 114 ports carry that label.
| port | service | risk | |||
|---|---|---|---|---|---|
| :9080 | Groove RPC | TCPUDP | Web Services | caution | 70.8k |
| :548 | Apple Filing Protocol | TCP | File Transfer | caution | 36.8k |
| :7000 | Vuze HTTPS Tracker | TCPtls | Security | caution | 28.9k |
| :1337 | PowerFolder P2P | TCP | Security | caution | 27.1k |
| :9001 | SharePoint Authoring | Web Services | caution | 26.3k | |
| :8080 | FilePhile Relay | UDP | File Transfer | caution | 25.6k |
| :1337 | WASTE Encrypted Sharing | TCP | Security | caution | 22.9k |
| :989 | FTPS Data | TCPUDPtls | Security | caution | 22.5k |
risk mix of the 8 listed
- caution100%
2 of 8 encrypted