Ftp – File copy between two ftp servers from a (third) local machine

filesftp

I have two ftp servers A and B. I need to copy a certain directory tree (and all files under it) from server A to server B. Is there a way to achieve this from my local machine (c) without having to run anything on server A and B?

EDIT All the three machines are on different networks but I have access to both the servers from my local m/c. Server B is a Akamai server (guessing it's linux) where we are hosting content and need to replicate content from the ftp server A (also a linux server)

Best Answer

To make this work the FTP servers you are connecting to must not explicitly prohibit server to server connection. You need a client capable of controlling the server to server request request.

The method for performing a server to server transfer is the same method used for an FTP Bounce Attack, so the server to server functionality is often prohibited by the configuration, or it is not even supported in some FTP servers.

Proftpd has a nice description of how the transfer takes place, and what you would have to do to make this supported under Proftpd.

Since you have no control of the two ftp servers in question, you almost certainly can't configure them to support the server to server communication. Since supporting server-to-server communication is disabled by default on almost every ftp daemon these days, it is unlikely that you will be able to make this work.

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Ftp – Why can’t I connect to some ftp servers from behind the win2008 NAT

The little-bit-of-text that does get through suggests it might be some sort of MTU problem. The best way to move forward is to install Wireshark on the gateway and capture all the traffic involved in the FTP connection. If you see a large packet being sent multiple times, it's MTU. Otherwise, paste the trace somewhere and someone can interpret it for you, if it isn't clear to you.

Linux – Copying a large directory tree locally? cp or rsync

I would use rsync as it means that if it is interrupted for any reason, then you can restart it easily with very little cost. And being rsync, it can even restart part way through a large file. As others mention, it can exclude files easily. The simplest way to preserve most things is to use the -a flag – ‘archive.’ So:

rsync -a source dest

Although UID/GID and symlinks are preserved by -a (see -lpgo), your question implies you might want a full copy of the filesystem information; and -a doesn't include hard-links, extended attributes, or ACLs (on Linux) or the above nor resource forks (on OS X.) Thus, for a robust copy of a filesystem, you'll need to include those flags:

rsync -aHAX source dest # Linux
rsync -aHE source dest  # OS X

The default cp will start again, though the -u flag will "copy only when the SOURCE file is newer than the destination file or when the destination file is missing". And the -a (archive) flag will be recursive, not recopy files if you have to restart and preserve permissions. So:

cp -au source dest

Best Answer

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Ftp – Why can’t I connect to some ftp servers from behind the win2008 NAT

Linux – Copying a large directory tree locally? cp or rsync

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