HTTPfy

Port 247 (subntbcst-tftp, subntbcst_tftp)

IANA assigns port 247 to subntbcst-tftp, subntbcst_tftp: SUBNTBCST_TFTP IANA assigned this well-formed service name as a replacement for "subntbcst_tftp"..

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
subntbcst-tftp TCP SUBNTBCST_TFTP IANA assigned this well-formed service name as a replacement for "subntbcst_tftp". John Fake -
subntbcst_tftp TCP SUBNTBCST_TFTP
This entry is an alias to "subntbcst-tftp". This entry is now historic, not usable for use with many common service discovery mechanisms. John Fake -
subntbcst-tftp UDP SUBNTBCST_TFTP IANA assigned this well-formed service name as a replacement for "subntbcst_tftp". John Fake -
subntbcst_tftp UDP SUBNTBCST_TFTP
This entry is an alias to "subntbcst-tftp". This entry is now historic, not usable for use with many common service discovery mechanisms. John Fake -

Check what is listening on port 247

Linux: is anything listening on TCP 247?
sudo ss -tlnp 'sport = :247'
Linux: UDP 247
sudo ss -ulnp 'sport = :247'
Linux / macOS: which process owns the port
sudo lsof -nP -i :247
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':247 '
Windows (Command Prompt)
netstat -ano | findstr :247
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 247 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 247
From Windows
Test-NetConnection HOST -Port 247
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 247

Block port 247 in the firewall

ufw
sudo ufw deny 247/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 247 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 247 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 247' -Direction Inbound -Protocol TCP -LocalPort 247 -Action Block
ufw
sudo ufw deny 247/udp
iptables
sudo iptables -A INPUT -p udp --dport 247 -j DROP
nftables
sudo nft add rule inet filter input udp dport 247 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 247' -Direction Inbound -Protocol UDP -LocalPort 247 -Action Block

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