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Port 565 (whoami)

IANA assigns port 565 to whoami.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
whoami TCP whoami - -
whoami UDP whoami - -

Check what is listening on port 565

Linux: is anything listening on TCP 565?
sudo ss -tlnp 'sport = :565'
Linux: UDP 565
sudo ss -ulnp 'sport = :565'
Linux / macOS: which process owns the port
sudo lsof -nP -i :565
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':565 '
Windows (Command Prompt)
netstat -ano | findstr :565
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 565 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 565
From Windows
Test-NetConnection HOST -Port 565
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 565

Block port 565 in the firewall

ufw
sudo ufw deny 565/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 565 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 565 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 565' -Direction Inbound -Protocol TCP -LocalPort 565 -Action Block
ufw
sudo ufw deny 565/udp
iptables
sudo iptables -A INPUT -p udp --dport 565 -j DROP
nftables
sudo nft add rule inet filter input udp dport 565 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 565' -Direction Inbound -Protocol UDP -LocalPort 565 -Action Block

Related ports

563NNTP over TLS5649pfs566streettalk567banyan-rpc

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