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Port 4597 (a21-an-1xbs)

IANA assigns port 4597 to a21-an-1xbs: A21 (AN-1xBS).

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
a21-an-1xbs TCP A21 (AN-1xBS) David Ott -
a21-an-1xbs UDP A21 (AN-1xBS) David Ott -

Registry dates for this port: registered 2006-02.

Check what is listening on port 4597

Linux: is anything listening on TCP 4597?
sudo ss -tlnp 'sport = :4597'
Linux: UDP 4597
sudo ss -ulnp 'sport = :4597'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4597
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4597 '
Windows (Command Prompt)
netstat -ano | findstr :4597
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4597 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4597
From Windows
Test-NetConnection HOST -Port 4597
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4597

Block port 4597 in the firewall

ufw
sudo ufw deny 4597/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4597 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4597 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4597' -Direction Inbound -Protocol TCP -LocalPort 4597 -Action Block
ufw
sudo ufw deny 4597/udp
iptables
sudo iptables -A INPUT -p udp --dport 4597 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4597 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4597' -Direction Inbound -Protocol UDP -LocalPort 4597 -Action Block

Related ports

4595ias-paging4596ias-neighbor4598a16-an-an4599a17-an-an

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