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when I try a scp transfer I get this error:

protocol error: bad mode

PD: I can establish a ssh connection.

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Does it make a difference if you do scp -1 or scp -2? – Dennis Williamson Mar 12 '11 at 1:47
up vote 2 down vote accepted

the problem was a personalized welcome message of bash

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So what's the solution? If you can't change the welcome message, is there a way to still scp? – Thucydides411 May 5 '14 at 16:26

So, this is a bit of question necromancy, but since I got here, and then realised what the answer was after reading the first answer, I figured I'd put this here for other wayward souls.

Because of the way scp works (over stdin/stdout over ssh AFAIK), having a naive bashrc that prints messages breaks the formatting scp is expecting, and thus the connection.

As suggested in various answers elsewhere (linked below), modifying your dot-files is usually the way to fix this:

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