“rsync over ssh” to a Synology NAS – IPKG, opkg

Nota Bene / before:

• This is the text, that helps me personally re-installing rsync, whenever it magically disappears, maybe caused by an DSM update.
• True, I should bring a little structure into this article.
• I never ever care about rsyncd, as I am doing “rsync over ssh”;  any activity suggested regarding rsyncd does not concern me. (But then sometimes I am misled, and I erroneously do invest time in false paths, and I do get into problems that are actually rsyncd-related.)
• I have my own ways of backing up data.
• I have my own ideas of keeping data long term outside my computer’s built-in disks.

The Synology system provided rsync is not for me. It’s somehow modified and spoilt.

• http://serverfault.com/questions/425589/rsync-over-ssh-error-module-is-read-only-suddenly-appeared

Well, it’s not only me experiencing weird effects with the “built-in” rsync. And I think, quite a few of the answers to that forum article do not quite fit at all.

The details of the case:

• “rsync over ssh” does not use the remote rsync daemon at all, i.e. no rsyncd.conf applies
• it’s not unlikely, that these rsync problems have to do with a Synology special version of rsync
• after this: “DiskStation> /usr/syno/etc.defaults/rc.d/S84rsyncd.sh stop”, the error message does not change, so it’s really not an “rsync daemon” issue, as that one is no longer running
• …

I mainly followed the “German Synology wiki” on IPKG. (As anxious as I am, I do keep a backup of that article at …/com/synology-wiki.de/ . Yes, I do have an idea, that this step alone is rather in vain.)
So, well 1st I had to install IPKG itself.
My CPU on the DS213+ is an e500 (actually: e500v2), so I went the e500 way in their description.
My CPU on the DS112+ is a “Feroceon 88FR131 rev 1 (v5l)”, there is a note on how to deal with the DS112+, pls follow that one.
My CPU on the DS115j is a “Marvell PJ4Bv7 Processor rev 1 (v7l)”, still a Feroceon, but a little hidden; the Feroceon check should be changed to check for Marvell instead; …

Then I installed the rsync package provided by IPKG.

An entry for /etc/rc.optware got created in /etc/rc.local, and they suggest to remove it, and I did that.
I am not sure, it concerns me at all, as I mention “my” rsync on the NAS by full path on my command lines outside the NAS.

Now my only minor problem with the “alternative rsync” is, that I have to specify the remote rsync on my local rsync command lines like this: “–rsync-path=/opt/bin/rsync”. That’s a PITA, but that’s not too hard.

Update 2013-08-31: en.wikipedia.org/wiki/Ipkg says IPKG was discontinued. en.wikipedia.org/wiki/Opkg is the follower, code.google.com/p/opkg/, but it hasn’t really taken off.