Port 3020Common Internet File System (CIFS)

IANA assigns TCP/UDP 3020 to CIFS, but SMB/CIFS file sharing is normally found on TCP 445 or legacy TCP 139.

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

also known as cifs, SMB

Technical Details

what runs on :3020

The IANA entry associates CIFS with TCP and UDP 3020, but there is no standard CIFS handshake or framing used on this port in common deployments. SMB/CIFS normally uses TCP 445 for direct hosting; older NetBIOS-hosted SMB uses TCP 139, with NetBIOS name and datagram services on UDP 137/138. On those TCP ports, clients negotiate an SMB dialect and then exchange framed file, printer, and session operations; 3020 should not be assumed to provide that service merely because of its registry assignment.

Security Information

exposure of :3020

risk score

2/ 10safe

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

file transfer averages 3.5 across 168 ports — this one sits 1.5 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

A real SMB/CIFS listener can expose file shares and authentication to password guessing, credential-relay attacks, and vulnerabilities in outdated implementations; it should not be exposed directly to the internet. SMB encryption is not guaranteed by default, and the low practical exposure of 3020 reflects that it is not a commonly deployed SMB port, not that an SMB service there would be safe.

Record

iana registry entry

port: :3020
service: Common Internet File System (CIFS)
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: File Transfer Network Services
usage: Port 3020 is registered as CIFS to Paul Leach, but it is not a standard listening port in ordinary deployments and has not been observed open in the cited internet-wide scan data. Engineers normally find SMB/CIFS on TCP 445, or legacy NetBIOS-hosted SMB on TCP 139.
lookups: 0rank 993
added: 2026-09-26
updated: 2026-09-26
references: IANA service name registry — port 3020

Something wrong?

This record is maintained by the engineers who use port 3020. 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 2026-09-26.

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 168 in file transfer →

the 8 most looked-up other ports in file transfer — 168 ports carry that label.

port	service	proto	category	risk	views
:9080	Groove RPC	TCPUDP	Web Services	caution	70.8k
:17500	Dropbox LAN Sync	TCPUDP	File Transfer	caution	43.7k
: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

risk mix of the 8 listed

caution100%

1 of 8 encrypted

Port :3020Common Internet File System (CIFS)

Technical Details

Security Information

Related Ports

Port 3020Common Internet File System (CIFS)