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Port 6620 (kftp-data)

IANA assigns port 6620 to kftp-data: Kerberos V5 FTP Data.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
kftp-data TCP Kerberos V5 FTP Data Robert J Scott -
kftp-data UDP Kerberos V5 FTP Data Robert J Scott -

Registry dates for this port: registered 2005-08.

Check what is listening on port 6620

Linux: is anything listening on TCP 6620?
sudo ss -tlnp 'sport = :6620'
Linux: UDP 6620
sudo ss -ulnp 'sport = :6620'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6620
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6620 '
Windows (Command Prompt)
netstat -ano | findstr :6620
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6620 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6620
From Windows
Test-NetConnection HOST -Port 6620
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6620

Block port 6620 in the firewall

ufw
sudo ufw deny 6620/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6620 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6620 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6620' -Direction Inbound -Protocol TCP -LocalPort 6620 -Action Block
ufw
sudo ufw deny 6620/udp
iptables
sudo iptables -A INPUT -p udp --dport 6620 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6620 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6620' -Direction Inbound -Protocol UDP -LocalPort 6620 -Action Block

Related ports

6610bencher6619odette-ftps6621kftp6622mcftp

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