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Editorial Team
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Asked: 2026-05-22T01:35:37+00:00

I’m having an issue with the socket.ntohl() function, on some hosts. It is repeatable

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I’m having an issue with the socket.ntohl() function, on some hosts. It is repeatable on all similar hosts; 32bit machines with Python 2.4.2.

>>> socket.ntohl(16777215)
-256

However the reverse seems to work fine –

>>> socket.htonl(4294967040)
16777215

Reading the docs, It doesn’t mention any limitations or warnings. Is this a bug in the Novell version of this old package? They are all Suse 9 machines 🙁

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1 Answer

  1. Editorial Team

    In older 32-bit Python versions, int was limited to a signed 32-bit number. 16777215 = 0x00FFFFFF and -256 in 32-bit 2s complement is 0xFFFFFF00.

    It works correctly in Python 2.7 by upgrading the value to a long:

    >>> socket.ntohl(16777215)
4294967040L
>>> hex(4294967040)
'0xffffff00L'

    Edit:

    Python 2.4 was the first version to unify int and long so what you see might be considered a bug that has been fixed by 2.7.

    Looks like this issue fixed it.

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