HTTPfy

Port 1621 (softdataphone)

IANA assigns port 1621 to softdataphone.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
softdataphone TCP softdataphone Dror Gill -
softdataphone UDP softdataphone Dror Gill -

Check what is listening on port 1621

Linux: is anything listening on TCP 1621?
sudo ss -tlnp 'sport = :1621'
Linux: UDP 1621
sudo ss -ulnp 'sport = :1621'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1621
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1621 '
Windows (Command Prompt)
netstat -ano | findstr :1621
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1621 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1621
From Windows
Test-NetConnection HOST -Port 1621
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1621

Block port 1621 in the firewall

ufw
sudo ufw deny 1621/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1621 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1621 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1621' -Direction Inbound -Protocol TCP -LocalPort 1621 -Action Block
ufw
sudo ufw deny 1621/udp
iptables
sudo iptables -A INPUT -p udp --dport 1621 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1621 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1621' -Direction Inbound -Protocol UDP -LocalPort 1621 -Action Block

Related ports

1619xs-openstorage1620faxportwinport1622ontime1623jaleosnd

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