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Port 635 (rlzdbase)

IANA assigns port 635 to rlzdbase: RLZ DBase.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
rlzdbase TCP RLZ DBase Michael Ginn -
rlzdbase UDP RLZ DBase Michael Ginn -

Check what is listening on port 635

Linux: is anything listening on TCP 635?
sudo ss -tlnp 'sport = :635'
Linux: UDP 635
sudo ss -ulnp 'sport = :635'
Linux / macOS: which process owns the port
sudo lsof -nP -i :635
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':635 '
Windows (Command Prompt)
netstat -ano | findstr :635
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 635 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 635
From Windows
Test-NetConnection HOST -Port 635
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 635

Block port 635 in the firewall

ufw
sudo ufw deny 635/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 635 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 635 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 635' -Direction Inbound -Protocol TCP -LocalPort 635 -Action Block
ufw
sudo ufw deny 635/udp
iptables
sudo iptables -A INPUT -p udp --dport 635 -j DROP
nftables
sudo nft add rule inet filter input udp dport 635 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 635' -Direction Inbound -Protocol UDP -LocalPort 635 -Action Block

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