Recursion's questions

These hosting facilities tend to be great, they are cheap and work well compared to other alternatives. Though while being cheap, there is a compromise to be made and I want to know if there is a way to not make that compromise.

The compromise being allowing clear access to possibly sensitive data being hosted by that provider, you are basically leaving sensitive code, databases and other files on these servers for any employee of the host who has access to take or steal.

So are there are protections available to keep them from seeing everything? I know some of you will say, well you should use a reputable host, which is good advice, but no matter how good they seem there can always be somebody corrupt.

Lets say I create a dump of a block device like so

dump -0 -A L0.archive -f L0.dump /dev/sde1

Now in this case sde1 is not mounted, as to not be live. So how can I restore sde1 from the other partition while sde1 is unmounted.

I have done some research online and some people claim dump/restore have good ext4 support and others claim the system is broken and restores come back corrupt. My question is, do they work well together, in your experience?

What is the difference between these two in a Bind9 setup? Also when one updates his list of current root servers, does one add them to root.hint or db.cache? I find multiple explanations online and none are really clear/

I am trying to set up my own DNS server, both for learning as well as for privacy. I installed Bind9 and tried to follow a few online tutorials, as well as the Linux Administration Handbook, but it still seems not to work. I set named.conf to listen on the localhost, and set it to be recursive. I then set resolv.conf to have only one nameserver which is 127.0.0.1.

I then tried to use it from my desktop and tried dig nyc.gov, as a site I had never been to before, I got the following resonse

 > dig nyc.gov

; <<>> DiG 9.7.0-P1 <<>> nyc.gov
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 54429
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;nyc.gov.           IN  A

;; Query time: 14 msec
;; SERVER: 97.107.138.191#53(97.107.138.191)
;; WHEN: Sun Aug  1 02:07:09 2010
;; MSG SIZE  rcvd: 25

It seems it needs to be recursive, though I set Bind to be, and yes I did restart the daemon.

Any tips would be appreciated, or any further tutorials on the matter. I mainly want an alternative DNS server for my colleagues and I. Thank you.

On a recent job posting for a general Unix admin at a datacenter, a listed requirement was to move live files in a data center setting. What does this mean and how can one move live files?

I am a bit confused, as there are two ways to install applications. One being to configure and make from source and the other from a package manager. If one were a UNIX/Linux administrator, is it fair to use package managers and is it trustworthy? I have come across a few places, which seems to say today's admins really don't know what they are doing, because they don't do things from scratch and instead prefer package management.

So as an aspiring UNIX admin, I know I should know both methoods and I do, but which should one choose first. As an example, on a job interview if asked to set up Apache, does one reach for the source or the package manager?

When people ask on how to wipe a drive, it almost seems as if the default answer is DBAN and I am not really sure why. Especially when doing commands like

dd if=/dev/zero of=/dev/sda
dd if=/dev/urandom of=/dev/sda
dcfldd pattern="00" of=/dev/sda
dcfldd pattern="FF" of=/dev/sda
shred /dev/sda
wipe /dev/sda
cat /dev/sda | cat > /dev/sda
etc

All of these will do the exact same thing and using a tool like hdparm to execute a secure-erase command will be much better than all of the above. Given that it will also erase those blocks on the glist,

So what makes Dban so good and so recommended. Is there a technical reason why it is recommended? To me it seems like a waste of bandwidth and a blank cd.

How can I made sendmail on FreeBSD listen to port 25 outside of the system, so I can receive mail from outside services. Currently it is only able to receive mail locally though it can send mail fine.

On a local LAN I am unable to connect to my FreeBSD8 server with OpenSSH. I can on the other hand ssh directly by IP address and it works fine.

The server as well as my workstation are behind the same NAT router which is the DNS relay/delegator to my isp. I have my hostname bound to my localhost in /etc/hosts.

Do I need to set up a local nameservice? Id like to rectify this problem.

I sometimes use dcfldd, because it has more features and is easier to use than regular dd. It gives a constant status and updates it fast, and it also has pattern input which is a lot faster than reading from /dev/zero or any other device.

As an example, let's say I wanted to wipe a drive with dcfldd I would do something like this

dcfldd pattern="00" of=/dev/hda bs=4096

Where it would write "00000000" to the drive byte by byte and then you can use the vf= function to verify the pattern.

But I noticed a bit of a problem and wanted to know if any of you can help. When I run this

dcfldd pattern="FF" of=/dev/hda bs=4096; sync
or
dcfldd pattern="11111111" of=/dev/hda bs=4096; sync

I can fill the drive with 1's and it does so very fast. I can fill a 74gb drive to let's say 5GB worth of 1's, after it has been zeroed. If I use a hex editor like xxd or hd in linux, I can see all of the 1's.

Though if I then run this command,

dcfldd pattern="00" of=/dev/hda bs=4096; sync

Let's say for only 1gb worth of 0's, there should still be 4gb worth of 1's. Seeing that I wrote 5gb of 1's and only 1gb of 0's over the 1's.

Though if I then look at a hex editor the drive is all 0's, even if the software states it only wrote 1gb of 0's. I have tried to run the program for as short as possible sending a SIGINT almost right after running.

Any idea on why this occurs and can you replicate it?

Our Management told us we needed to wipe down some our drives, who knows why. We were told to delete certain documents and then backup the remaining files to a external medium, wipe then restore the remaining files.

I usually just use Dump/Restore to do backups as it works great and is very simple. I simply used rm() to delete the files, created a zeroed file to fill the drive, deleted that file, then did a level 0 dump to a external medium, did a secure-erase via the drives firmware and now am restoring.

Though I have to ask, since dump works with the inodes and filesystem, will there be a trace of the deleted files in the dump of the drive, possible any metadata or links left over? This seemed pretty important to management, so I don't want to let them down because of my archaic backup habits.

I am using dcfldd to wipe a drive and lear forensics. I don't really want to have to deal with the math of the blocks and sectors, and just want dd or dcfldd to write over every possible bit on the drive or device.

As an example I saw this example on a site, too write ones to a drive

dcfldd pattern="11111111" of=/dev/hda bs=4096 conv=sync,notrunc

Why do you need 8 one's(I assume to make a byte) and what does notrunc mean, as well as the sync option. Also with the bs= option, is bigger always better and faster?

I have read the man page but don't understand the keywords.

So I made a dump of one of my drives today which totalled 171GB and did a level 0 dump which had a output size of 58GB.

I dont know why it was so small, but I wanted to ask if dump searches for a past level 0 even when you instruct it to do a level 0. There is another level 0 on the drive from September.

Linux 2.6 Kernel EXt3

We have a server running an ext3 drive running Linux and then another workstation running Windows with a NTFS drive.

When users use Windows they use the NTFS and when they are in Linux they connect directly to the ext3.

We use rsync a lot to copy files from the ext3 to the NTFS and it works great, but when we delete files on the ext3 we also want them deleted on the NTFS and we use the --delete-after to do this. It works great but we would like it to query the user asking if they wanted to delete the file or not. Is such possible?

Also sometimes users use the ext3 then go into Windows and use the NTFS and make changes to it. Now if we were to sync the ext3 to the NTFS we would lose changes made on the ext3 before this. Is there a better way to make sure these drives are synced up better.

The reason we have it set up like this is mainly due to the lack of support for ext3 in Windows and my feeling that ext3 is a more developed FS than NTFS.

I had a tar file which was of size 3.5gb which held all my programming code.
I was working with git trying to learn the repositories, so I created this file as a backup, so I could work my code directory and if anything were to go wrong I could just delete and extract it.

I did this a few times and it worked great, then I restarted and remounted my drive and the tar file was not 10kb instead of 3,5gb and all its contents were gone.

What could have happened?

Is CCNA and its study books a good way to learn and understand networking on both cisco and non cisco equipment. I want to buy a good reference book, but dont want to be tied down cisco proprietary terms and equipment.

I understand the basics of networking such as Lan and stuff. I know what many of the protocols are and how to build a client/server socket program in C. But what I really want is a very good understanding of how networks actually work. Not only from a programming aspect but also from a application aspect. I am looking for some material(preferably a book) which will give me a very good foundation to go off of. I am in the middle of wanting to be a programmer or a UNIX admin, so I really should learn and know how to apply networking fundamentals.

Does any such a concise resource exist? Would it be better going the more academic route by buying a networking book(such as those from Tanenbaum or Kurose), or is it better to go the It route possibly looking into network admin text or certification books.

Thank you all so much.

Is it possible to integrate the newest packages into an ubuntu install.

When you image a drive with dd, you get a image usually of the same exact size of the drive. You can compress the image, but that is really Dependant on how many continuous null's or zeros their are on the drive. My question is, does another tool exist to only image the critical blocks of the drive. Such as with a fresh install of an OS, is it possible to only copy up to the last block utilized by the new os?

while I know dd doesn't have such abilities, does such already exist, and if it does then does that app use dd.