- Restrict management and monitoring protocols to the monitoring network.
- Replace community strings and default credentials.
- Send logs over TLS.
Port 3857: Trap Port
Port 3857 is assigned by IANA to trap-port (Trap Port).
3857
How trap-port works
Monitoring & loggingThe monitoring server collects metrics, alerts or logs from devices over port 3857.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Registered (1024-49151)
- Category
- Monitoring & logging
Is port 3857 dangerous?
We have no specific security note for port 3857. Its risk depends on the program actually listening on it. General advice for monitoring & logging services:
IANA registry entries for port 3857
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| trap-port | 3857 | TCP, UDP | Trap Port | - | 2003-08 |
// source: IANA service name and port number registry
Which program uses port 3857, and is it reachable?
Linux
sudo ss -ltnup 'sport = :3857' # process listening on 3857
sudo lsof -nP -i :3857macOS
sudo lsof -nP -i :3857
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3857 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 3857 netstat -ano | findstr :3857
From another machine
nmap -p 3857 -sV <host> sudo nmap -sU -p 3857 <host> nc -zv <host> 3857
Block it in the firewall
sudo ufw deny 3857/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 3857" -Direction Inbound -LocalPort 3857 -Protocol TCP -Action Block # Windows
What is port 3857 used for?
Port 3857 is assigned by IANA to trap-port (Trap Port).
Is port 3857 TCP or UDP?
Port 3857 is registered for TCP and UDP.
Is it safe to open port 3857?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Restrict management and monitoring protocols to the monitoring network.
How do I check if port 3857 is open?
On Linux run "ss -ltnup 'sport = :3857'", on macOS "lsof -nP -i :3857", and on Windows "netstat -ano | findstr :3857" to see the local process. From another machine, "nmap -p 3857 <host>" shows whether it is reachable.
Other monitoring & logging ports
:161 SNMP udp · tcp · high risk :162 SNMP trap udp · tcp · moderate risk :9090 Prometheus / admin consoles tcp · udp · high risk :514 Syslog udp · tcp · moderate risk :6514 Syslog over TLS tcp · udp · dccp · low risk :5601 Kibana tcp · udp · high risk :391 SynOptics SNMP Relay Port tcp · udp :412 Trap Convention Port tcp · udp