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Port 1435 (ibm-cics)

IANA assigns port 1435 to ibm-cics: IBM CICS.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ibm-cics TCP IBM CICS Geoff Meacock -
ibm-cics UDP IBM CICS Geoff Meacock -

Check what is listening on port 1435

Linux: is anything listening on TCP 1435?
sudo ss -tlnp 'sport = :1435'
Linux: UDP 1435
sudo ss -ulnp 'sport = :1435'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1435
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1435 '
Windows (Command Prompt)
netstat -ano | findstr :1435
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1435 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1435
From Windows
Test-NetConnection HOST -Port 1435
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1435

Block port 1435 in the firewall

ufw
sudo ufw deny 1435/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1435 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1435 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1435' -Direction Inbound -Protocol TCP -LocalPort 1435 -Action Block
ufw
sudo ufw deny 1435/udp
iptables
sudo iptables -A INPUT -p udp --dport 1435 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1435 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1435' -Direction Inbound -Protocol UDP -LocalPort 1435 -Action Block

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