- Bind the service to localhost or a private network, never to a public address.
- Enable authentication, use per-application accounts and require TLS.
- Watch for exposed Docker ports: publish them on 127.0.0.1 only.
Port 156: SQL Service
Port 156 is assigned by IANA to sqlsrv (SQL Service).
156
How sqlsrv works
Databases & cachesThe application sends a SQL query to the sqlsrv server on port 156, which returns rows from its tables.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Well-known (0-1023)
- Category
- Databases & caches
Is port 156 dangerous?
We have no specific security note for port 156. Its risk depends on the program actually listening on it. General advice for databases & caches services:
IANA registry entries for port 156
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| sqlsrv | 156 | TCP, UDP | SQL Service | - | - |
// source: IANA service name and port number registry
Which program uses port 156, and is it reachable?
Linux
sudo ss -ltnup 'sport = :156' # process listening on 156
sudo lsof -nP -i :156macOS
sudo lsof -nP -i :156
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 156 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 156 netstat -ano | findstr :156
From another machine
nmap -p 156 -sV <host> sudo nmap -sU -p 156 <host> nc -zv <host> 156
Block it in the firewall
sudo ufw deny 156/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 156" -Direction Inbound -LocalPort 156 -Protocol TCP -Action Block # Windows
What is port 156 used for?
Port 156 is assigned by IANA to sqlsrv (SQL Service).
Is port 156 TCP or UDP?
Port 156 is registered for TCP and UDP.
Is it safe to open port 156?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Bind the service to localhost or a private network, never to a public address.
How do I check if port 156 is open?
On Linux run "ss -ltnup 'sport = :156'", on macOS "lsof -nP -i :156", and on Windows "netstat -ano | findstr :156" to see the local process. From another machine, "nmap -p 156 <host>" shows whether it is reachable.
Other databases & caches ports
:3306 MySQL / MariaDB tcp · udp · high risk :1433 Microsoft SQL Server tcp · udp · high risk :5432 PostgreSQL tcp · udp · high risk :6379 Redis tcp · critical risk :27017 MongoDB tcp · critical risk :9200 Elasticsearch tcp · udp · critical risk :1521 Oracle Database tcp · udp · high risk :11211 Memcached tcp · udp · high risk