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views:

27

answers:

2
+1  Q: 

X-Forwarded-For (XFF) HTTP header

How many characters can the value of the X-Forwarded-For (XFF) HTTP header value be?

Example is: X-Forwarded-For: client1, proxy1, proxy2

A: 

See this, this and this (related SO questions).

The spec does not specify a limit (so, unlimited, in theory). However, there is a limit that is implementation specific.

IIS 6/7 allow up to 16K per header, apache will default to 8K.

Oded  2010-08-01 19:37:47
A: 

AFAIK, there is no limit. Note that you shouldn't rely on its value; it can be spoofed easily.

You  2010-08-01 19:40:29

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