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What's the difference (if any) between 'span' and 'JBOD'?
by Chris G 30 Dec '09

30 Dec '09

My Western Digital NAS server offers me (among other RAID formats) both 'span' and 'JBOD'. I thought they were synonyms for the same thing, that is using the disks 'as is' with no RAID processing. If they're different can anyone explain the difference please. -- Chris Green

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sshfs versus just using ssh/rsync
by Chris G 30 Dec '09

30 Dec '09

Is there any difference between the two following strategies for backing up files to a remote system:- 1 Mount the remote destination directory using sshfs/fuser Copy the files to the 'local' directory just mounted using rsync, rdiff-backup or whatever. 2 Copy the files directly to the remote system using rsync or rdiff-backup. Strategy 1 has the significant advantage that the remote system doesn't have to have anything other than ssh available. You don't run into any issues with mismatched versions of rdiff-backup or anything like that. Both strategies require that you set up some form of 'passwordless' login to the remote system or you need to enter the password (or passphrase) when the backup is run. I was thinking that I can run either of these from my .xprofile so that by the time they are run the required passphrase has been entered. I was even thinking that I could run the backup to one remote system from my wife's desktop .xprofile and to the other from my desktop .xprofile so they'd be at different times and to different remote systems, most unlikely to get both damaged at the same time. Only someone breaking into my working X environment would get access to the backups, just breaking into my home systems wouldn't do it. They might of course break into the remote systems I use for backup but then I have my home backups that haven't been compromised. -- Chris Green

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i18n
by Steve 30 Dec '09

30 Dec '09

Seasons Eatings all, I've been playing around with getting my laptop all nice and easy to use in a joint English / Turkish environment. I've got a key combination bound to switching the keyboard layout between GB and TR but when I do so, I lose some (but not all) of the custom keys I had set up with xmodmap. I think what I'm really asking is: has anyone had any experience of working with a dual (or multi) language environment and do you have any nuggets of information or things to look out for? Or even just some cunning xmodmap foo I should be aware of? On an unrelated note, this year marks my 10th anniversary of using linux and I've just been reflecting on how much cooler things seem now. We're a long way from the days of waiting half a day to download the latest kernel, another half a day to compile it, two more days working out how to get the new kernel to support your winmodem and then the fun of hacking X.conf :) More stuff seems to just work these days and it feels a lot more comfortable. Or maybe that's because I've been with it for 10 years. Anyhoo, enough rambling. See some of you for the first pubmeet of 2010 soon :D Steve

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Some success with seahorse and gnome-keyring-daemon at last
by Chris G 30 Dec '09

30 Dec '09

Well, after searching and asking and digging around in the code I have finally got things working as I believe they should work. That is I have a default keyring being automatically opened for me when I log in. It took me a while because firstly there isn't much documentation telling you how you're supposed to use it and secondly because (in xubuntu 9.10 at least) it's broken so it doesn't work even if you do things right. There are two problems:- 1 - By default ssh-agent gets started as well as gnome-keyring-daemon, as they're both trying to do the same thing this isn't a good idea. I've stopped ssh-agent being started automatically by deleting the use-ssh-agent line from /etc/X11/Xsession.options. I'm sure there should be a GUI way of changing this but I don't know what it is. 2 - Although gnome-keyring-daemon is started automatically it isn't set up to listen on the ssh socket. To fix this I have added the following to my .xprofile:- eval $(gnome-keyring-daemon --start) export SSH_AUTH_SOCK export GNOME_KEYRING_SOCKET This second is definitely a bodge but at least it gets things working, there are several bugs reported around this area in more than one linux distribution - in fact that's how I eventually found out how to sort it out. So, now my login password is *also* used to unlock the default keyring and ssh can interrogate that keyring to get my private key to log in to other systems. .... and it really is just about passwordless, or at least I don't have to enter any more passwords after login, but my private keys are kept reasonably safe. I suppose having my login password the same as my key passphrase is a bit less than perfect but this is only for connections going outwards from my home system so isn't very critical really. Now I'm off to those external systems to make them a bit more secure as regards logging into the home system. It's a pity there aren't any 'hooks' in ssh-agent and login that would allow you to do the same for direct ssh logins as happens with Gnome/KDE, then you could do the same sort of thing and enter only one password for connecting onwards. -- Chris Green

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Efficient power supplies - especially at very low powers - suppliers?
by Chris G 30 Dec '09

30 Dec '09

While this isn't particularly Linux related it is PC related and I'd guess some people here may be knowledgeable in this area. I'm trying to cut down my PCs' power consumption, one way has been to offload 'server' functions from my desktop machine to a much lower power server machine. That's now done and I'm looking at other ways to reduce power consumption. I've been looking at the power consumption of my desktop machine and noticed that when in standby it consumes about 20 watts. So I checked how much it consumed when powered down completely (but still conencted) and it *still* consumed 20 watts. I.e. the power supply and motherboard even when completely idle take 20 watts. I suspect that this is mostly power supply losses. When powered up, even though it's quite a fast machine (quad core processor, 8Gb of memory, two big disk drives) it only takes 50 watts so the power supply isn't all that inefficient when it's working. So how can I search for power supplies that don't take much power when completely idle? Typical 'efficient' 300 watt and 400 watt power supplies are better than 80% efficient but that means they may well still consume 20 watts when doing nothing. Efficiency *doesn't* necessarily equate to low 'off' power. -- Chris Green

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Re: [ALUG] Windows software for managing remote Linux SVN server?
by Srdjan Todorovic 21 Dec '09

21 Dec '09

On 18/12/2009, mick <mbm(a)rlogin.net> wrote: > On Thu, 17 Dec 2009 11:32:32 +0000 > Srdjan Todorovic <todorovic.s(a)googlemail.com> allegedly wrote: > >> Hi all, >> >> I'm looking for some simple to use Windows software that can >> administer a remote SVN server that runs on Linux. >> > > Best not ask here about windows software, you'll upset the faithful..... > > :-) Well I've mentioned Linux and SVN, so hopefully that will keep the zealots happy. :) Srdjan

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Windows software for managing remote Linux SVN server?
by Srdjan Todorovic 21 Dec '09

21 Dec '09

Hi all, I'm looking for some simple to use Windows software that can administer a remote SVN server that runs on Linux. Specifically, I'm looking for something that can create a repository, and setup users and change passwords. Normal SVN activities (code browsing/checking in/merging/diffing etc) will be run as normal. I'm currently looking into http://www.sublimesvn.com/ but I'm not sure I like the licensing (why would each developer have to be licensed?). Thanks Srdjan

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Wireless Internet Link Security
by Ian 20 Dec '09

20 Dec '09

Hi Folks, The lady of the house wants a wireless internet connection for her laptop for Christmas as she is fed up with "tripping over cables everywhere!". I have purchased a router and laptop dongle and am experimenting with it so it is ready for The Big Day. One thing which is confusing me is the security modes it offers. It gives me the choice of using any of the following 5 modes: No Security WEP WPA-PSK (TKIP) WPA2-PSK (AES) WPA-PSK (TKIP) + WPA2-PSK (AES) or Mixed Mode I do not expect Security to be a big problem but I may as well set it up the best I can right from the start. Assuming the laptop dongle can also be configured for all five security modes mentioned above which is the best mode to use? (Sorry if the above seems a dumb question to all you experienced network admin bods but this is the first time I have touched a wireless Router and am not sure what I am doing) Ian.

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How best to run a 'pull' backup using passwordless login?
by Chris G 20 Dec '09

20 Dec '09

As part of my sort out and tidy up of security, backups, etc. I've decided that it would be better to run my off site backups as 'pull' backups driven from the remote systems. This way an intruder into my home system won't see any evidence of these backups happening and hence won't be tempted to do anything to them. This requires (unless someone else has some bright ideas) that the remote system has a passwordless login to enable it to do the backup (or I put the password in the script, which comes to the same thing). For this to be (reasonably) secure it needs to be set up so that the *only* thing you can do with that login is a backup. So, finally to my question, what's the tidiest/easiest way of doing this? I can see two possible ways:- A dedicated login with the program to be executed when you login set to do the backup. A 'ForceCommand' in ssh that executes the backup when certain criteria are met. I think I prefer the second as it makes handling permissions etc. easier. E.g. I want to backup files belonging to user xxxx, if I can login as user xxxx then I don't need to worry about the files all being readable by the backup. This requires careful setting up of the sshd_config file though so that remote logins to user xxxx run the backup but one can still login to user xxxx locally. Can anyone see any serious flaws in the above and/or easier ways of doing it that are still reasonably secure? -- Chris Green

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Gnome, seahorse, gnome-keyring-daemon - any good howtos or overviews anywhere?
by Chris G 18 Dec '09

18 Dec '09

I'm considering (though I'm rapidly going off the idea at the moment) using seahorse and gnome-keyring to manage passwords/keys etc. None of the manuals gives a clue as to what they all actually *do*. All you get is information about the mechanics of entering data into seahorse etc. which is pretty straightforward and obvious anyway. I want to know how it actually works to make keeping keys etc. easier and to make logging in to other systems easier. At present I do things manually by editing and copying the various files in $HOME/.ssh directly myself. I don't run ssh-agent, I *assume* that gnome-keyring is a sort of replacement for that but can't find anything that tells me anything actually useful. What concerns me slightly is that it's all a total waste of time if it's only protected by my login password which I think, by default, it is. I.e. if I understand things right (and I'm not at all sure about this) when I log in to the X gui and enter my password then gnome-keyring (and/or seahorse) extracts my key[s] from somewhere and then when I ssh to other systems that key is used and I don't have to type it in. Have I got that anything like right? If this *is* the way that it works how is it even remotely more secure than simply using password login on those systems I ssh into? If not can someone clarify a bit for me, or, as I said, point me at some sort of overview document that explains things. -- Chris Green

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