Port 3876DirectoryLockdown Agent

DirectoryLockdown Agent traffic uses TCP and UDP port 3876.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 1/10
lookups: 0

also known as dl_agent, dl-agent

Technical Details

what runs on :3876

DirectoryLockdown Agent is registered on port :3876 over tcp and udp to Jason Lockett][Melanie Kacerek, assigned December 2008. We don't have a technical write-up for it beyond the IANA registry entry.

In nmap's internet-wide scan data this port is found open rarely. What's listening is often not the registered service, so check before you assume.

find what's listening on :3876

this machine

# linux
sudo ss -tulpn 'sport = :3876'

# macos / bsd
sudo lsof -nP -i :3876

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :3876

another host

nmap -sV -p T:3876 <host>
sudo nmap -sU -sV -p U:3876 <host>

run it? the handshake, the implementations you meet in the wild and the flags that matter come from the engineers who do.

add technical details

Security Information

exposure of :3876

risk score

1/ 10safe

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

security averages 3.1 across 363 ports — this one sits 2.1 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

no security notes recorded for :3876 yet

known exploits, hardening advice, what a compromise looks like — suggest an edit if you know its exposure.

Record

iana registry entry

port: :3876
service: DirectoryLockdown Agent
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: Security
usage: Port 3876 was assigned to the DirectoryLockdown Agent and is registered to Jason Lockett and Melanie Kacerek. The assignment is historic and aliases the service name "dl-agent"; it is rarely observed.
lookups: 0rank 993
added: 2026-09-13
updated: 2026-09-13
references: IANA service name registry — port 3876

Something wrong?

This record is maintained by the engineers who use port 3876. 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 2026-09-13.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

all 363 in security →

the 8 most looked-up other ports in security — 363 ports carry that label.

port	service	proto	category	risk	views
:8881	Atlasz Secure Server	TCP	Web Services	caution	67.6k
:443	HTTPS	TCPtls	Web Services	caution	65.9k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:3268	Microsoft Global Catalog (GC)	TCPUDP	Security	caution	54.6k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:3128	Squid Proxy HTTP	TCP	Web Services	caution	45.8k
:8080	HTTP Alternate	TCP	Web Services	caution	44.9k
:7000	Vuze HTTPS Tracker	TCPtls	Security	caution	28.9k

risk mix of the 8 listed

caution100%

2 of 8 encrypted

Port :3876DirectoryLockdown Agent

Technical Details

Security Information

Related Ports

Port 3876DirectoryLockdown Agent