What is the NET file format?
.net files are plain-text configuration files used to define network parameters. The most specifically documented use is the rc.net file in IBM AIX - a Unix-based operating system - where AIX reads this shell script at boot time to configure network interfaces, hostnames, and static routes using commands such as ifconfig and route.
The .net extension carries no universal standard; it is shared by many unrelated tools. In IBM AIX the file is a shell script, sometimes beginning with a #!/bin/sh shebang. In other environments such as MATLAB or various network analysis utilities, .net files may use an INI-like stanza format of key=value pairs. Because the format is plain text throughout, any text editor can read and modify these files.
In modern AIX deployments, direct editing of rc.net scripts has largely been replaced by higher-level tools such as smitty and the persistent Object Data Manager (ODM), making the raw .net script approach a legacy practice.
The extension is unrelated to Microsoft's .NET framework; .net configuration files and .NET assemblies are entirely different things. Related plain-text configuration formats include .cfg and .conf files. Because there is no fixed file signature, the content and structure of a .net file must be determined from context or the associated application.
Security & safety
RISK: LOWPlain text file; the AIX rc.net is a shell script but is only executed by the AIX init system at boot on a server. No risk from simply opening it in a text editor on any platform.
Format details
in a nutshell- MATLAB Network Data File - MATLAB neural network toolbox has used .net for saved network object files in legacy versions.
- Game network/map file (various games) - Several older games (e.g., Neverwinter Nights area network, others) used .net for internal level or network topology data.
- Microsoft .NET assembly (rare collision) - Occasionally .net appears as an assembly or configuration artifact in .NET projects, though standard .NET files use .config, .dll, .exe extensions.
Programs that open NET files
Windows1 app
Linux2 apps
IBM AIX - Unix operating system
Paid Edit /etc/rc.net with vi, nano, or any text editor on AIX. The file is executed automatically at boot by the AIX init system. 
any text editor (Linux/Mac/Windows)
Open-source Open in Notepad++ (Windows), gedit/nano (Linux), or TextEdit (Mac) - it is a plain text file. Technical details
deep spec| Encoding | Plain text - ASCII or UTF-8 |
| Container | Shell script (IBM AIX context) or INI-like stanza format (other tools) |
| IBM AIX role | Boot-time network configuration script; calls `ifconfig`, `route`, and related commands to set up interfaces |
| File signature | None - plain text; AIX `rc.net` may open with a `#!/bin/sh` shebang line |
| Typical size | 1 KB - 50 KB |
| Configuration scope (AIX) | Network interface addresses, netmask, default gateway, hostname, and static routes |
| OS association | IBM AIX (primary documented use); also Linux (some tools) and Windows-adjacent network utilities |
| Legacy status | Superseded in modern AIX by `smitty` and Object Data Manager (ODM) persistent configuration |
| MIME type | `text/plain` |
| Ambiguity | Extension shared by many unrelated applications (MATLAB, game files, analysis tools); no universal specification |
| Released | early 1990s (IBM AIX context) |
| Latest version | AIX 7.2+ (current, format stable) |
| Specification | www.ibm.com |
NET conversions
Community Q&A
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