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Port 58 (xns-mail)

IANA assigns port 58 to xns-mail: XNS Mail.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
xns-mail TCP XNS Mail Susie Armstrong -
xns-mail UDP XNS Mail Susie Armstrong -

Check what is listening on port 58

Linux: is anything listening on TCP 58?
sudo ss -tlnp 'sport = :58'
Linux: UDP 58
sudo ss -ulnp 'sport = :58'
Linux / macOS: which process owns the port
sudo lsof -nP -i :58
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':58 '
Windows (Command Prompt)
netstat -ano | findstr :58
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 58 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 58
From Windows
Test-NetConnection HOST -Port 58
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 58

Block port 58 in the firewall

ufw
sudo ufw deny 58/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 58 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 58 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 58' -Direction Inbound -Protocol TCP -LocalPort 58 -Action Block
ufw
sudo ufw deny 58/udp
iptables
sudo iptables -A INPUT -p udp --dport 58 -j DROP
nftables
sudo nft add rule inet filter input udp dport 58 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 58' -Direction Inbound -Protocol UDP -LocalPort 58 -Action Block

Related ports

56xns-auth57any private terminal access59any private file service62acas

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