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Port 1996 (tr-rsrb-port)

IANA assigns port 1996 to tr-rsrb-port: cisco Remote SRB port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
tr-rsrb-port TCP cisco Remote SRB port - -
tr-rsrb-port UDP cisco Remote SRB port - -

Check what is listening on port 1996

Linux: is anything listening on TCP 1996?
sudo ss -tlnp 'sport = :1996'
Linux: UDP 1996
sudo ss -ulnp 'sport = :1996'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1996
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1996 '
Windows (Command Prompt)
netstat -ano | findstr :1996
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1996 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1996
From Windows
Test-NetConnection HOST -Port 1996
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1996

Block port 1996 in the firewall

ufw
sudo ufw deny 1996/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1996 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1996 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1996' -Direction Inbound -Protocol TCP -LocalPort 1996 -Action Block
ufw
sudo ufw deny 1996/udp
iptables
sudo iptables -A INPUT -p udp --dport 1996 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1996 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1996' -Direction Inbound -Protocol UDP -LocalPort 1996 -Action Block

Related ports

1994stun-port1995perf-port1997gdp-port1998x25-svc-port

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