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Port 4357 (qsnet-cond)

IANA assigns port 4357 to qsnet-cond: QSNet Conductor.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
qsnet-cond TCP QSNet Conductor - -
qsnet-cond UDP QSNet Conductor - -

Check what is listening on port 4357

Linux: is anything listening on TCP 4357?
sudo ss -tlnp 'sport = :4357'
Linux: UDP 4357
sudo ss -ulnp 'sport = :4357'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4357
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4357 '
Windows (Command Prompt)
netstat -ano | findstr :4357
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4357 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4357
From Windows
Test-NetConnection HOST -Port 4357
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4357

Block port 4357 in the firewall

ufw
sudo ufw deny 4357/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4357 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4357 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4357' -Direction Inbound -Protocol TCP -LocalPort 4357 -Action Block
ufw
sudo ufw deny 4357/udp
iptables
sudo iptables -A INPUT -p udp --dport 4357 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4357 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4357' -Direction Inbound -Protocol UDP -LocalPort 4357 -Action Block

Related ports

4355qsnet-workst4356qsnet-assist4358qsnet-nucl4359omabcastltkm

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