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Port 48128 (isnetserv)

IANA assigns port 48128 to isnetserv: Image Systems Network Services.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
isnetserv TCP Image Systems Network Services Bengt Gustafsson -
isnetserv UDP Image Systems Network Services Bengt Gustafsson -

Registry dates for this port: registered 2006-05.

Check what is listening on port 48128

Linux: is anything listening on TCP 48128?
sudo ss -tlnp 'sport = :48128'
Linux: UDP 48128
sudo ss -ulnp 'sport = :48128'
Linux / macOS: which process owns the port
sudo lsof -nP -i :48128
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':48128 '
Windows (Command Prompt)
netstat -ano | findstr :48128
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 48128 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 48128
From Windows
Test-NetConnection HOST -Port 48128
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 48128

Block port 48128 in the firewall

ufw
sudo ufw deny 48128/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 48128 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 48128 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 48128' -Direction Inbound -Protocol TCP -LocalPort 48128 -Action Block
ufw
sudo ufw deny 48128/udp
iptables
sudo iptables -A INPUT -p udp --dport 48128 -j DROP
nftables
sudo nft add rule inet filter input udp dport 48128 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 48128' -Direction Inbound -Protocol UDP -LocalPort 48128 -Action Block

Related ports

480493gpp-cbsp48050weandsf48129blp548556com-bardac-dw

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