Port 3876 (dl-agent, dl_agent)

IANA assigns port 3876 to dl-agent, dl_agent: DirectoryLockdown Agent IANA assigned this well-formed service name as a replacement for "dl_agent"..

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

dl-agent TCP DirectoryLockdown Agent IANA assigned this well-formed service name as a replacement for "dl_agent". Jason Lockett, Melanie Kacerek -

dl_agent TCP DirectoryLockdown Agent
This entry is an alias to "dl-agent". This entry is now historic, not usable for use with many common service discovery mechanisms. Jason Lockett, Melanie Kacerek -

dl-agent UDP DirectoryLockdown Agent IANA assigned this well-formed service name as a replacement for "dl_agent". Jason Lockett, Melanie Kacerek -

dl_agent UDP DirectoryLockdown Agent
This entry is an alias to "dl-agent". This entry is now historic, not usable for use with many common service discovery mechanisms. Jason Lockett, Melanie Kacerek -

Registry dates for this port: registered 2008-12-16.

Check what is listening on port 3876

Linux: is anything listening on TCP 3876?

sudo ss -tlnp 'sport = :3876'

Linux: UDP 3876

sudo ss -ulnp 'sport = :3876'

Linux / macOS: which process owns the port

sudo lsof -nP -i :3876

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':3876 '

Windows (Command Prompt)

netstat -ano | findstr :3876

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3876 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine

nc -vz -w 5 HOST 3876

From Windows

Test-NetConnection HOST -Port 3876

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 3876

Block port 3876 in the firewall

ufw

sudo ufw deny 3876/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 3876 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 3876 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 3876' -Direction Inbound -Protocol TCP -LocalPort 3876 -Action Block

ufw

sudo ufw deny 3876/udp