Dial-up networking file
application/octet-stream
Magic Bytes
Offset: 0
5B 56 45 52 5D
The Dial-up networking (DUN) file is a legacy configuration format developed by Microsoft for defining remote access parameters on early Windows operating systems. These files store connection details such as telephone numbers, modem commands, and network protocols to facilitate the automated configuration of dial-up adapters. Although rendered largely obsolete by modern broadband technologies, the format remains a safe, text-based standard with minimal security risks beyond the potential exposure of connection-specific metadata.
Validation Code
How to validate .dun files in Python
Python
def is_dun(file_path: str) -> bool:
"""Check if file is a valid DUN by magic bytes."""
signature = bytes([0x5B, 0x56, 0x45, 0x52, 0x5D])
with open(file_path, "rb") as f:
return f.read(5) == signatureHow to validate .dun files in Node.js
Node.js
function isDUN(buffer: Buffer): boolean {
const signature = Buffer.from([0x5B, 0x56, 0x45, 0x52, 0x5D]);
return buffer.subarray(0, 5).equals(signature);
}
Go
func IsDUN(data []byte) bool {
signature := []byte{0x5B, 0x56, 0x45, 0x52, 0x5D}
if len(data) < 5 {
return false
}
return bytes.Equal(data[:5], signature)
}API Endpoint
GET
/api/v1/dun
curl https://filesignature.org/api/v1/dun