Re: netmask for loopback interfaces

From: Oleksandr Kryvulia <>
Date: Thu, 04 Nov 2021 06:05:13 UTC
04.11.21 01:01, Mike Karels пишет:
> I have a pending change to stop using class A/B/C netmasks when setting
> an interface address without an explicit mask, and instead to use a default
> mask (24 bits).  A question has arisen as to what the default mask should
> be for loopback interfaces.  The standard is added with an 8 bit
> mask currently, but additions without a mask would default to 24 bits.
> There is no warning for missing masks for loopback in the current code.
> I'm not convinced that the mask has any meaning here; only a host route
> to the assigned address is created.  Does anyone know of any meaning or
> use of the mask on a loopback address?
> Thanks,
> 		Mike

/8 mask on loopback prevetnts using of 127.x.x.x network anywhere 
outside of the localhost. This described in RFC 5735 [1] and 1122 [2]