HTTPfy

Port 4453 (nssalertmgr)

IANA assigns port 4453 to nssalertmgr: NSS Alert Manager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
nssalertmgr TCP NSS Alert Manager - -
nssalertmgr UDP NSS Alert Manager - -

Check what is listening on port 4453

Linux: is anything listening on TCP 4453?
sudo ss -tlnp 'sport = :4453'
Linux: UDP 4453
sudo ss -ulnp 'sport = :4453'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4453
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4453 '
Windows (Command Prompt)
netstat -ano | findstr :4453
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4453 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4453
From Windows
Test-NetConnection HOST -Port 4453
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4453

Block port 4453 in the firewall

ufw
sudo ufw deny 4453/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4453 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4453 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4453' -Direction Inbound -Protocol TCP -LocalPort 4453 -Action Block
ufw
sudo ufw deny 4453/udp
iptables
sudo iptables -A INPUT -p udp --dport 4453 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4453 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4453' -Direction Inbound -Protocol UDP -LocalPort 4453 -Action Block

Related ports

4451ctisystemmsg4452ctiprogramload4454nssagentmgr4455prchat-user

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