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Port 355 (datex-asn)

IANA assigns port 355 to datex-asn: DATEX-ASN.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
datex-asn TCP DATEX-ASN Kenneth Vaughn -
datex-asn UDP DATEX-ASN Kenneth Vaughn -

Check what is listening on port 355

Linux: is anything listening on TCP 355?
sudo ss -tlnp 'sport = :355'
Linux: UDP 355
sudo ss -ulnp 'sport = :355'
Linux / macOS: which process owns the port
sudo lsof -nP -i :355
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':355 '
Windows (Command Prompt)
netstat -ano | findstr :355
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 355 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 355
From Windows
Test-NetConnection HOST -Port 355
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 355

Block port 355 in the firewall

ufw
sudo ufw deny 355/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 355 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 355 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 355' -Direction Inbound -Protocol TCP -LocalPort 355 -Action Block
ufw
sudo ufw deny 355/udp
iptables
sudo iptables -A INPUT -p udp --dport 355 -j DROP
nftables
sudo nft add rule inet filter input udp dport 355 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 355' -Direction Inbound -Protocol UDP -LocalPort 355 -Action Block

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353ndsauth354bh611356cloanto-net-1357bhevent

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