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// Web

Port 8888: Jupyter / HTTP alternate

Default port of Jupyter Notebook and various proxies.

Jupyter Notebook
8888

How Jupyter / HTTP alternate works

Web
browser:8888pw=1234 browser:8888pw=1234

A browser sends an HTTP request to port 8888 and the Jupyter / HTTP alternate server sends the page back. It travels in clear text: anyone on the path can read it, passwords included.

Transport
TCP · UDP
Exposure risk
7/10 high if reachable from the Internet
Encryption
Clear textreadable on the network
IANA status
Assignedcommon use differs from the registry
Range
Registered (1024-49151)
Category
Web
01 Security

Is port 8888 dangerous?

Common attacks and weaknesses

  • Notebooks without token give arbitrary code execution.

How to secure it

  • Keep token or password authentication and bind to localhost; use SSH tunnels.

Unofficial use. The IANA assignment below differs from what is usually found on this port in practice.

02 Registry

IANA registry entries for port 8888

ServicePortTransportDescriptionReferenceUpdated
ddi-tcp-1 8888 TCP NewsEDGE server TCP (TCP 1)
Reported: Known Unauthorized Use on port 8888
 - -
ddi-udp-1 8888 UDP NewsEDGE server UDP (UDP 1)
Reported: Known Unauthorized Use on port 8888
 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 8888, and is it reachable?

Linux

sudo ss -ltnup 'sport = :8888'      # process listening on 8888
sudo lsof -nP -i :8888

macOS

sudo lsof -nP -i :8888

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 8888 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 8888
netstat -ano | findstr :8888

From another machine

nmap -p 8888 -sV <host>
sudo nmap -sU -p 8888 <host>
nc -zv <host> 8888

Block it in the firewall

sudo ufw deny 8888/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 8888" -Direction Inbound -LocalPort 8888 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 8888 used for?

Default port of Jupyter Notebook and various proxies.

Is port 8888 TCP or UDP?

Port 8888 is registered for TCP and UDP. In practice the service mostly uses TCP.

Is it safe to open port 8888?

It is rated 7/10 (high) when exposed to the Internet. Notebooks without token give arbitrary code execution. Keep token or password authentication and bind to localhost; use SSH tunnels.

How do I check if port 8888 is open?

On Linux run "ss -ltnup 'sport = :8888'", on macOS "lsof -nP -i :8888", and on Windows "netstat -ano | findstr :8888" to see the local process. From another machine, "nmap -p 8888 <host>" shows whether it is reachable.

05 Related
:443 HTTPS tcp · udp · sctp · low risk :80 HTTP tcp · udp · sctp · moderate risk :8080 HTTP alternate tcp · udp · high risk :8443 HTTPS alternate tcp · udp · moderate risk :3000 Dev servers / Grafana tcp · udp · moderate risk :5000 Flask / Docker registry / UPnP tcp · udp · moderate risk :8000 HTTP alternate (dev) tcp · udp · moderate risk :9443 HTTPS alternate (admin) tcp · udp · moderate risk

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