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Port 18634 (rds-ib)

IANA assigns port 18634 to rds-ib: Reliable Datagram Service.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
rds-ib TCP Reliable Datagram Service Andy Grover -
rds-ib UDP Reliable Datagram Service Andy Grover -

Registry dates for this port: registered 2009-02-27.

Check what is listening on port 18634

Linux: is anything listening on TCP 18634?
sudo ss -tlnp 'sport = :18634'
Linux: UDP 18634
sudo ss -ulnp 'sport = :18634'
Linux / macOS: which process owns the port
sudo lsof -nP -i :18634
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':18634 '
Windows (Command Prompt)
netstat -ano | findstr :18634
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 18634 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 18634
From Windows
Test-NetConnection HOST -Port 18634
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 18634

Block port 18634 in the firewall

ufw
sudo ufw deny 18634/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 18634 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 18634 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 18634' -Direction Inbound -Protocol TCP -LocalPort 18634 -Action Block
ufw
sudo ufw deny 18634/udp
iptables
sudo iptables -A INPUT -p udp --dport 18634 -j DROP
nftables
sudo nft add rule inet filter input udp dport 18634 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 18634' -Direction Inbound -Protocol UDP -LocalPort 18634 -Action Block

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