Port 1604Citrix ICA Browser

Citrix ICA Browser discovery service for published applications and XenApp or MetaFrame servers.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as Citrix MetaFrame ICA Browser

Technical Details

what runs on :1604

ICA Browser listens on both TCP and UDP port 1604. UDP is used for browser announcements and discovery, while clients can query a specific server over the browser service to obtain published application and server information. The browser exchange is a legacy, generally cleartext discovery protocol and is separate from the ICA session transport, commonly TCP 1494, or TCP 2598 when Session Reliability is enabled.

Security Information

exposure of :1604

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

remote access averages 3.6 across 179 ports — this one sits 1.6 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

The service should normally be restricted to trusted internal networks rather than exposed to the Internet. Unrestricted access can disclose Citrix server and published-application information, and legacy implementations may be susceptible to scanning or denial-of-service; it does not by itself provide the authenticated application session.

Record

iana registry entry

port: :1604
service: Citrix ICA Browser
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Remote Access Network Services
usage: This port is used by legacy Citrix XenApp and MetaFrame deployments to discover Citrix servers and published applications. It supports ICA Browser queries and announcements; the actual ICA session commonly uses TCP 1494 or TCP 2598.
lookups: 0rank 994
added: 2026-09-17
updated: 2026-09-17
references: IANA service name registry — port 1604

Something wrong?

This record is maintained by the engineers who use port 1604. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-17.

01edit any field on a page of its own
02a model checks it for accuracy and spam
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edit this record →back to the registry

Related Ports

all 179 in remote access →

the 8 most looked-up other ports in remote access — 179 ports carry that label.

port	service	proto	category	risk	views
:8000	Intel Remote Desktop / Alternate HTTP Port	TCP	Web Services	safe	84.3k
:8888	D2GS Admin Console	TCP	Remote Access	caution	83.7k
:8881	Atlasz Secure Server	TCP	Web Services	caution	67.6k
:5938	TeamViewer	TCPUDP	Remote Access	caution	65.0k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:8008	IBM HTTP Server Admin	TCP	Web Services	caution	58.3k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:23	Telnet	TCP	Remote Access	caution	34.8k

risk mix of the 8 listed

safe13%
caution88%

0 of 8 encrypted

Port :1604Citrix ICA Browser

Technical Details

Security Information

Related Ports

Port 1604Citrix ICA Browser