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Port 3871 (avocent-adsap)

IANA assigns port 3871 to avocent-adsap: Avocent DS Authorization.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
avocent-adsap TCP Avocent DS Authorization Eduardo Fernandez -
avocent-adsap UDP Avocent DS Authorization Eduardo Fernandez -

Registry dates for this port: registered 2003-08.

Check what is listening on port 3871

Linux: is anything listening on TCP 3871?
sudo ss -tlnp 'sport = :3871'
Linux: UDP 3871
sudo ss -ulnp 'sport = :3871'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3871
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3871 '
Windows (Command Prompt)
netstat -ano | findstr :3871
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3871 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3871
From Windows
Test-NetConnection HOST -Port 3871
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3871

Block port 3871 in the firewall

ufw
sudo ufw deny 3871/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3871 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3871 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3871' -Direction Inbound -Protocol TCP -LocalPort 3871 -Action Block
ufw
sudo ufw deny 3871/udp
iptables
sudo iptables -A INPUT -p udp --dport 3871 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3871 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3871' -Direction Inbound -Protocol UDP -LocalPort 3871 -Action Block

Related ports

3869ovsam-mgmt3870ovsam-d-agent3872oem-agent3873fagordnc

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.