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Port 519 (utime)

IANA assigns port 519 to utime: unixtime.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
utime TCP unixtime - -
utime UDP unixtime - -

Check what is listening on port 519

Linux: is anything listening on TCP 519?
sudo ss -tlnp 'sport = :519'
Linux: UDP 519
sudo ss -ulnp 'sport = :519'
Linux / macOS: which process owns the port
sudo lsof -nP -i :519
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':519 '
Windows (Command Prompt)
netstat -ano | findstr :519
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 519 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 519
From Windows
Test-NetConnection HOST -Port 519
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 519

Block port 519 in the firewall

ufw
sudo ufw deny 519/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 519 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 519 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 519' -Direction Inbound -Protocol TCP -LocalPort 519 -Action Block
ufw
sudo ufw deny 519/udp
iptables
sudo iptables -A INPUT -p udp --dport 519 -j DROP
nftables
sudo nft add rule inet filter input udp dport 519 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 519' -Direction Inbound -Protocol UDP -LocalPort 519 -Action Block

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