HTTPfy

Port 3923 (symb-sb-port)

IANA assigns port 3923 to symb-sb-port: Symbian Service Broker.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
symb-sb-port TCP Symbian Service Broker Ian McDowall -
symb-sb-port UDP Symbian Service Broker Ian McDowall -

Registry dates for this port: registered 2003-11.

Check what is listening on port 3923

Linux: is anything listening on TCP 3923?
sudo ss -tlnp 'sport = :3923'
Linux: UDP 3923
sudo ss -ulnp 'sport = :3923'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3923
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3923 '
Windows (Command Prompt)
netstat -ano | findstr :3923
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3923 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3923
From Windows
Test-NetConnection HOST -Port 3923
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3923

Block port 3923 in the firewall

ufw
sudo ufw deny 3923/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3923 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3923 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3923' -Direction Inbound -Protocol TCP -LocalPort 3923 -Action Block
ufw
sudo ufw deny 3923/udp
iptables
sudo iptables -A INPUT -p udp --dport 3923 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3923 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3923' -Direction Inbound -Protocol UDP -LocalPort 3923 -Action Block

Related ports

3921herodotus-net3922sor-update3924mpl-gprs-port3925zmp

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