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Port 1988 (tr-rsrb-p2)

IANA assigns port 1988 to tr-rsrb-p2: cisco RSRB Priority 2 port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
tr-rsrb-p2 TCP cisco RSRB Priority 2 port - -
tr-rsrb-p2 UDP cisco RSRB Priority 2 port - -

Check what is listening on port 1988

Linux: is anything listening on TCP 1988?
sudo ss -tlnp 'sport = :1988'
Linux: UDP 1988
sudo ss -ulnp 'sport = :1988'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1988
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1988 '
Windows (Command Prompt)
netstat -ano | findstr :1988
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1988 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1988
From Windows
Test-NetConnection HOST -Port 1988
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1988

Block port 1988 in the firewall

ufw
sudo ufw deny 1988/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1988 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1988 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1988' -Direction Inbound -Protocol TCP -LocalPort 1988 -Action Block
ufw
sudo ufw deny 1988/udp
iptables
sudo iptables -A INPUT -p udp --dport 1988 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1988 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1988' -Direction Inbound -Protocol UDP -LocalPort 1988 -Action Block

Related ports

1986licensedaemon1987tr-rsrb-p11989tr-rsrb-p3, mshnet1990stun-p1

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