IPV6, Fedora and apps

John DeDourek dedourek at unb.ca
Wed May 31 15:58:52 UTC 2006



Douglas Phillipson wrote:

> Do network applications written for Fedora, or any Linux distro for that 
> matter, require any modification to work with IPv6?  or is that a 
> "TRANSPARENT" change in the protocol stack under the application layer? 
>  Is there a different API for IPv6 for network apps, socket servers, etc?
> 
> Thanks
> 
> Doug P
> 

I have programmed some simple IPv4 applications in C.  I have not programmed
any IPv6 applications.  But I do work with network protocols.  With that
disclaimer:

There are a significant number of details that need to be accommodated to
handle IPv6.  Just consider, for example, the size of the address is now
16 bytes instead of 4 bytes.  A typical application will read a host name
from somewhere (e.g. a browser extracts this from a URL) and then needs
to do a "get host address by name" call to a library function to get
the IP address before it can use the network access functions.  Now a
C program needs to have allocated sufficient space within it to hold
the 16 byte address.  It is likely that most C programs will at least
in some cases not have been careful enough to automatically increase
the allocation when recompiled for IPv6 access.  Also, IIRC, some of the
function names have changed to prevent bugs due to putting an IPv6
address in an allocation only 4 bytes long.

Conclusion:  an application written in C will need to be carefully examined
and likely modified to support IPv6.  I can't speak for applications implemented
in other languages.




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