Port 2781 (whosells)

IANA assigns port 2781 to whosells.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

whosells TCP whosells William Randolph Roy -

whosells UDP whosells William Randolph Roy -

Linux: is anything listening on TCP 2781?

sudo ss -tlnp 'sport = :2781'

Linux: UDP 2781

sudo ss -ulnp 'sport = :2781'

Linux / macOS: which process owns the port

sudo lsof -nP -i :2781

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':2781 '

Windows (Command Prompt)

netstat -ano | findstr :2781

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2781 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 2781

From Windows

Test-NetConnection HOST -Port 2781

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

nc -vzu -w 5 HOST 2781

ufw

sudo ufw deny 2781/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 2781 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 2781 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 2781' -Direction Inbound -Protocol TCP -LocalPort 2781 -Action Block

ufw

sudo ufw deny 2781/udp

iptables

sudo iptables -A INPUT -p udp --dport 2781 -j DROP

nftables

sudo nft add rule inet filter input udp dport 2781 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 2781' -Direction Inbound -Protocol UDP -LocalPort 2781 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.