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Port 3864 (asap-tcp-tls, asap-sctp-tls)

IANA assigns port 3864 to asap-tcp-tls, asap-sctp-tls: asap/tls tcp port.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
asap-tcp-tls TCP asap/tls tcp port - RFC 5352
asap-sctp-tls SCTP asap-sctp/tls - RFC 5352

Check what is listening on port 3864

Linux: is anything listening on TCP 3864?
sudo ss -tlnp 'sport = :3864'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3864
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3864 '
Windows (Command Prompt)
netstat -ano | findstr :3864
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3864 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3864
From Windows
Test-NetConnection HOST -Port 3864

Block port 3864 in the firewall

ufw
sudo ufw deny 3864/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3864 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3864 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3864' -Direction Inbound -Protocol TCP -LocalPort 3864 -Action Block

Related ports

3862giga-pocket3863asap-tcp, asap-udp, asap-sctp3865xpl3866dzdaemon

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