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Registered port (1024–10000) High risk

Port 9200 ELASTICSEARCH

Quick answer

Port 9200 is most commonly used by Elasticsearch. The IANA registry lists TCP / UDP for this number.

Check and block Is it safe? Troubleshooting FAQ
TransportTCP / UDP
RiskHigh
Typical useSearch and analytics

What is port 9200 used for?

Port 9200 is most commonly used by Elasticsearch. Elasticsearch exposes its REST API on port 9200 by default; the IANA registry lists wap-wsp, the WAP connectionless session service. It sits in the registered range, the block used by databases, application servers and developer tooling. Port conflicts here are common when several local services start at once.

Ports are the transport-layer address a service listens on. A client that wants to reach wap-wsp connects to port 9200. A TCP connection is refused when nothing is listening, while a UDP request simply goes unanswered. That is why a port conflict appears whenever two processes try to bind the same number.

Use the commands below to confirm whether port 9200 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.

Source: IANA Service Name and Transport Protocol Port Number Registry. Registered assignee: [WAP_Forum].

Check and block port 9200

Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.

Check on Linux

sudo ss -tlpn 'sport = :9200' sudo ss -ulpn 'sport = :9200'

Check on Windows

Get-NetTCPConnection -LocalPort 9200 -State Listen -ErrorAction SilentlyContinue Get-NetUDPEndpoint -LocalPort 9200 -ErrorAction SilentlyContinue

Block with UFW

sudo ufw deny 9200/tcp sudo ufw deny 9200/udp

Block with iptables

sudo iptables -A INPUT -p tcp --dport 9200 -j DROP sudo iptables -A INPUT -p udp --dport 9200 -j DROP

These commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled.

Is port 9200 safe to expose?

High

Elasticsearch historically shipped without authentication and is a frequent data-leak and ransomware target. Require authentication and never expose it publicly. Treat this port as sensitive. Restrict it to trusted networks or a VPN, require authentication and logging, and never expose it directly to the public internet without a hardened gateway in front.

Where port 9200 is usually used

Most traffic on port 9200 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.

Demo

Check Elasticsearch health

The cluster health endpoint returns JSON and is safe to call without changing data.

curl -s "http://127.0.0.1:9200/_cluster/health?pretty"

Common problems with port 9200

Connection refused or timed out

Refused usually means the host is reachable but nothing is listening on port 9200. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.

Port already in use

Find the process holding the port with sudo ss -tlpn 'sport = :9200' or sudo lsof -i :9200. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.

Firewall rule did not survive a reboot

UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.

The port is blocked but still reachable

A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.

Port 9200 at a glance

Port number9200
IANA service namewap-wsp
Commonly used byElasticsearch
Transport protocolTCP / UDP
CategorySearch and analytics
RangeRegistered port (1024–10000)
Risk levelHigh
Registered assignee[WAP_Forum]
Registry descriptionWAP connectionless session service
SourceIANA Service Name and Transport Protocol Port Number Registry

Frequently asked questions

What is port 9200 used for?

Port 9200 (ELASTICSEARCH). The IANA registry lists TCP / UDP for this number. Elasticsearch exposes its REST API on port 9200 by default; the IANA registry lists wap-wsp, the WAP connectionless session service.

How do I check if port 9200 is open?

On Linux run `sudo ss -tlpn 'sport = :9200'` and `sudo ss -ulpn 'sport = :9200'`. On Windows run `Get-NetTCPConnection -LocalPort 9200 -State Listen -ErrorAction SilentlyContinue` and `Get-NetUDPEndpoint -LocalPort 9200 -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 9200; empty output usually means nothing is bound to it.

How do I block port 9200?

With UFW run `sudo ufw deny 9200/tcp` and `sudo ufw deny 9200/udp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 9200 -j DROP` and `sudo iptables -A INPUT -p udp --dport 9200 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot.

Is port 9200 safe to expose?

Elasticsearch historically shipped without authentication and is a frequent data-leak and ransomware target. Require authentication and never expose it publicly. Nevertheless, treat this port as sensitive. Restrict it to trusted networks or a VPN, require authentication and logging, and never expose it directly to the public internet without a hardened gateway in front.

Primary data: IANA Service Name and Transport Protocol Port Number Registry.

Last reviewed 2026-10-30 · Methodology · About · Privacy