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crc not installed but rsync using it? ...

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  crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-24 15:10 +0200
    Re: crc not installed but rsync using it? ... Greg Wooledge <wooledg@eeg.ccf.org> - 2020-09-24 15:30 +0200
    Re: crc not installed but rsync using it? ... Thomas Pircher <thp+debian@p5r.uk> - 2020-09-24 15:40 +0200
      Re: crc not installed but rsync using it? ... Greg Wooledge <wooledg@eeg.ccf.org> - 2020-09-24 18:00 +0200
      Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-24 18:00 +0200
        Re: crc not installed but rsync using it? ... Thomas Pircher <thp+debian@p5r.uk> - 2020-09-24 18:30 +0200
        Re: crc not installed but rsync using it? ... Reco <recoverym4n@enotuniq.net> - 2020-09-24 19:10 +0200
          Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-29 16:00 +0200
            Re: crc not installed but rsync using it? ... Dan Ritter <dsr@randomstring.org> - 2020-09-29 16:50 +0200
            Re: crc not installed but rsync using it? ... Reco <recoverym4n@enotuniq.net> - 2020-09-29 16:50 +0200
        Re: crc not installed but rsync using it? ... Sven Hartge <sven@svenhartge.de> - 2020-09-24 20:30 +0200
          Re: crc not installed but rsync using it? ... David Wright <deblis@lionunicorn.co.uk> - 2020-09-25 01:00 +0200
            Re: crc not installed but rsync using it? ... Jonathan Dowland <jon+debian-user@dow.land> - 2020-09-25 11:40 +0200
              Re: crc not installed but rsync using it? ... David Wright <deblis@lionunicorn.co.uk> - 2020-09-26 04:50 +0200
              Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-29 16:00 +0200
                Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-29 16:30 +0200
                  Re: crc not installed but rsync using it? ... Andrei POPESCU <andreimpopescu@gmail.com> - 2020-10-01 09:00 +0200
            Re: crc not installed but rsync using it? ... Greg Wooledge <wooledg@eeg.ccf.org> - 2020-09-25 13:50 +0200
              Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-25 14:00 +0200
                Re: crc not installed but rsync using it? ... Gene Heskett <gheskett@shentel.net> - 2020-09-25 15:10 +0200
                  Re: crc not installed but rsync using it? ... John Hasler <jhasler@newsguy.com> - 2020-09-25 15:30 +0200
                    Re: crc not installed but rsync using it? ... Gene Heskett <gheskett@shentel.net> - 2020-09-25 16:00 +0200
                      Re: crc not installed but rsync using it? ... John Hasler <jhasler@newsguy.com> - 2020-09-25 18:10 +0200
                        Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-25 18:20 +0200
                          Re: crc not installed but rsync using it? ... John Hasler <jhasler@newsguy.com> - 2020-09-25 19:40 +0200
                            Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-25 20:20 +0200
                            Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-26 00:10 +0200
                              Re: crc not installed but rsync using it? ... John Hasler <jhasler@newsguy.com> - 2020-09-26 00:30 +0200
                                Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-26 00:50 +0200
                        Re: crc not installed but rsync using it? ... Gene Heskett <gheskett@shentel.net> - 2020-09-25 19:00 +0200
                          Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-26 00:20 +0200
                            Re: crc not installed but rsync using it? ... Gene Heskett <gheskett@shentel.net> - 2020-09-26 00:50 +0200
                              Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-26 01:00 +0200
                              Re: crc not installed but rsync using it? ... mick crane <mick.crane@gmail.com> - 2020-09-26 02:00 +0200
                                Re: crc not installed but rsync using it? ... Dan Ritter <dsr@randomstring.org> - 2020-09-26 16:50 +0200
                  Re: crc not installed but rsync using it? ... Michael Stone <mstone@debian.org> - 2020-09-25 16:30 +0200
                    Re: crc not installed but rsync using it? ... Gene Heskett <gheskett@shentel.net> - 2020-09-25 17:00 +0200
                      Re: crc not installed but rsync using it? ... Michael Stone <mstone@debian.org> - 2020-09-25 17:30 +0200
                        Re: crc not installed but rsync using it? ... Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-25 17:40 +0200
                    Re: crc not installed but rsync using it? ... Andrei POPESCU <andreimpopescu@gmail.com> - 2020-09-25 17:10 +0200
                      Re: crc not installed but rsync using it? ... Tixy <tixy@yxit.co.uk> - 2020-09-25 18:30 +0200
                        Re: crc not installed but rsync using it? ... Brian <ad44@cityscape.co.uk> - 2020-09-25 20:00 +0200
          Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-25 13:50 +0200
            Re: crc not installed but rsync using it? ... Dan Ritter <dsr@randomstring.org> - 2020-09-25 15:00 +0200
            Re: crc not installed but rsync using it? ... Michael Stone <mstone@debian.org> - 2020-09-25 15:50 +0200
              Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-26 14:20 +0200
                Re: crc not installed but rsync using it? ... Michael Stone <mstone@debian.org> - 2020-09-26 22:20 +0200
                  Re: crc not installed but rsync using it? ... Albretch Mueller <lbrtchx@gmail.com> - 2020-09-29 15:50 +0200
                    Re: crc not installed but rsync using it? ... David Wright <deblis@lionunicorn.co.uk> - 2020-09-29 16:50 +0200
                      Re: crc not installed but rsync using it? ... Fabrice BAUZAC-STEHLY <noon@mykolab.com> - 2020-10-01 13:30 +0200
            Re: crc not installed but rsync using it? ... Andrei POPESCU <andreimpopescu@gmail.com> - 2020-09-25 16:50 +0200

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#227357

On Fri, 2020-09-25 at 18:07 +0300, Andrei POPESCU wrote:
> On Vi, 25 sep 20, 10:23:43, Michael Stone wrote:
> > On Fri, Sep 25, 2020 at 09:01:26AM -0400, Gene Heskett wrote:
> > > 
[...]
> > > such a setup in a router running dd-wrt. In nearly 2 decades, no one has
> > > come into my systems from the internet that I didn't give the
> > > credentials to do so.
> > 
> > You post this all the time, but it's irrelevant at best and misleading at
> > worst. On a default debian system these days an external firewall is
> > basically a noop because there are no services listening.
> 
> Well, besides exim (still installed by default as far as I know), CUPS 
> (probably pulled by most DEs)

On my lamptop exim and cups are only listening on address 127.0.0.1.
The only other listening process is init (systemd) listening on 0.0.0.0
port 111. Hmm, that's rpcbind, installed by using NFS shares? Good job
I have a firewall between me and the internet ;-) (But seriously, one
thing I hadn't considerer for the very rare time I use public wifi).

-- 
Tixy

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#227363

On Fri 25 Sep 2020 at 17:21:03 +0100, Tixy wrote:

> On Fri, 2020-09-25 at 18:07 +0300, Andrei POPESCU wrote:
> > On Vi, 25 sep 20, 10:23:43, Michael Stone wrote:
> > > On Fri, Sep 25, 2020 at 09:01:26AM -0400, Gene Heskett wrote:
> > > > 
> [...]
> > > > such a setup in a router running dd-wrt. In nearly 2 decades, no one has
> > > > come into my systems from the internet that I didn't give the
> > > > credentials to do so.
> > > 
> > > You post this all the time, but it's irrelevant at best and misleading at
> > > worst. On a default debian system these days an external firewall is
> > > basically a noop because there are no services listening.
> > 
> > Well, besides exim (still installed by default as far as I know), CUPS 
> > (probably pulled by most DEs)
> 
> On my lamptop exim and cups are only listening on address 127.0.0.1.
> The only other listening process is init (systemd) listening on 0.0.0.0
> port 111. Hmm, that's rpcbind, installed by using NFS shares? Good job
> I have a firewall between me and the internet ;-) (But seriously, one
> thing I hadn't considerer for the very rare time I use public wifi).

An exim4 installation does indeed only listen on localhost:

  dc_local_interfaces='127.0.0.1 ; ::1'

in /etc/exim4/update-exim4.conf.conf.

Also, exim4 has Priority: optional and is no longer part of a default
installation.

The default cupsd.conf has

  Listen localhost:631

A dd-wrt based router using packet filtering contributes nothing in
this situation.

-- 
Brian.

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#227330

On 9/24/20, Sven Hartge <sven@svenhartge.de> wrote:

> Why do you think you need to do this? What do you hope to achieve by
> doing this?

 I have losts of (not necessarily all) text files (say in the 10 of
thousands) in various directories which I need to process in a batch,
but before I do that I want to make sure that I get a baseline of the
source files. I use:

 a)  crc
 b)  md5sum
 c) sha###sum

 because those are three different checksum utilities based on
different algorithms which work fast enough and offer a set signatures
which are good enough.

 My thinking may (once again) be a bit unhinged, but I would use,
e.g., crc because it internatlly used by rsync, which I also use in my
code.

 So, how do you think I can improve my baselining of the source files?

 L

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#227338

Albretch Mueller wrote: 
> On 9/24/20, Sven Hartge <sven@svenhartge.de> wrote:
> 
> > Why do you think you need to do this? What do you hope to achieve by
> > doing this?
> 
>  I have losts of (not necessarily all) text files (say in the 10 of
> thousands) in various directories which I need to process in a batch,
> but before I do that I want to make sure that I get a baseline of the
> source files. I use:
> 
>  a)  crc
>  b)  md5sum
>  c) sha###sum
> 
>  because those are three different checksum utilities based on
> different algorithms which work fast enough and offer a set signatures
> which are good enough.
> 
>  My thinking may (once again) be a bit unhinged, but I would use,
> e.g., crc because it internatlly used by rsync, which I also use in my
> code.
> 
>  So, how do you think I can improve my baselining of the source files?

If you want to defend against on-disk corruption, use ZFS.

If you want to be alerted to every change to a set of files, use
tripwire or aide. Both are packaged for Debian.

If you want to make sure that a directory full of files doesn't
change during processing, remove your write privileges for that
directory. "sudo chmod a-w DIRECTORY" will do that.

If you want to make sure of the previous case but you are going
to run a process that runs as root and you aren't sure it won't
assign itself write privileges, "sudo chattr +i DIRECTORY" will
make it immutable.

Don't reinvent the wheel.

-dsr-

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#227345

On Fri, Sep 25, 2020 at 01:49:25PM +0200, Albretch Mueller wrote:
> I have losts of (not necessarily all) text files (say in the 10 of
>thousands) in various directories which I need to process in a batch,
>but before I do that I want to make sure that I get a baseline of the
>source files. I use:
>
> a)  crc
> b)  md5sum
> c) sha###sum
>
> because those are three different checksum utilities based on
>different algorithms which work fast enough and offer a set signatures
>which are good enough.

Just one would be good enough (pick the sha256sum). What you're doing is 
a waste of time. If you want to future proof then use sha3, via the 
rhash package.

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#227393

On 9/25/20, Michael Stone <mstone@debian.org> wrote:
> Just one would be good enough (pick the sha256sum). What you're doing is
> a waste of time. If you want to future proof then use sha3, via the
> rhash package.

 Something that I have noticed is that texts are too close to people's
hearts to expect for people to just be technical about them. I use
those three algorithms because some people "understand", md5 and not
sha###sum. I mean, you may get some legacy data with their md5sum but
the maintainers of the data may not be around. Once I found an rsync
log that included the CRC signatures, that is why I include these
kinds fo algorithms.

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#227404

On Sat, Sep 26, 2020 at 02:11:30PM +0200, Albretch Mueller wrote:
>On 9/25/20, Michael Stone <mstone@debian.org> wrote:
>> Just one would be good enough (pick the sha256sum). What you're doing is
>> a waste of time. If you want to future proof then use sha3, via the
>> rhash package.
>
> Something that I have noticed is that texts are too close to people's
>hearts to expect for people to just be technical about them. I use
>those three algorithms because some people "understand", md5 and not
>sha###sum. I mean, you may get some legacy data with their md5sum but
>the maintainers of the data may not be around. Once I found an rsync
>log that included the CRC signatures, that is why I include these
>kinds fo algorithms.

Sorry, still makes no sense and is a waste of time. You're creating new 
hashes right now, it doesn't matter if someone else might have made some 
other hash some other time.

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#227472

On 9/26/20, Michael Stone <mstone@debian.org> wrote:
> On Sat, Sep 26, 2020 at 02:11:30PM +0200, Albretch Mueller wrote:
>>On 9/25/20, Michael Stone <mstone@debian.org> wrote:
>>> Just one would be good enough (pick the sha256sum). What you're doing is
>>> a waste of time. If you want to future proof then use sha3, via the
>>> rhash package.
>>
>> Something that I have noticed is that texts are too close to people's
>>hearts to expect for people to just be technical about them. I use
>>those three algorithms because some people "understand", md5 and not
>>sha###sum. I mean, you may get some legacy data with their md5sum but
>>the maintainers of the data may not be around. Once I found an rsync
>>log that included the CRC signatures, that is why I include these
>>kinds fo algorithms.
>
> Sorry, still makes no sense and is a waste of time. You're creating new
> hashes right now, it doesn't matter if someone else might have made some
> other hash some other time.

 But how could you have some assurance that that data relates to what
their users thought of to be?

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#227480

On Tue 29 Sep 2020 at 15:50:35 (+0200), Albretch Mueller wrote:
> On 9/24/20, Reco <recoverym4n@enotuniq.net> wrote:
> > On Thu, Sep 24, 2020 at 05:50:16PM +0200, Albretch Mueller wrote:
> >> >> How do I get all packages to be locally installed using dpkg from a
> >> >> public Windows machine?
> >> >
> >> > I'm not sure I understand this question or how it relates to the
> >> > previous one.
> >>
> >>  How do I get the deb files in order to install locally (via dpkg
> >> --install) the necessary utilities to run CRC32 and/or CRC64
> >
> > Typical Debian install has perl already, so you don't have to install
> > anything - [1].
> >
> > [1] http://billauer.co.il/blog/2011/05/perl-crc32-crc-xs-module/
> 
>  But I don't see anything when I go:
> 
>  which crc, crc32, crc64 ...

Imagine you did find an executable called crc32. What would you do
with it?

You find some data that's in an archive file called foo.zap. The
program zap claims to include a crc32 check within the archive.
Do you expect to type   crc32 --check foo.zap   and get some
meaningful output, or what?

On Tue 29 Sep 2020 at 15:48:09 (+0200), Albretch Mueller wrote:
> On 9/26/20, Michael Stone <mstone@debian.org> wrote:
> > On Sat, Sep 26, 2020 at 02:11:30PM +0200, Albretch Mueller wrote:
> >>On 9/25/20, Michael Stone <mstone@debian.org> wrote:
> >>> Just one would be good enough (pick the sha256sum). What you're doing is
> >>> a waste of time. If you want to future proof then use sha3, via the
> >>> rhash package.
> >>
> >> Something that I have noticed is that texts are too close to people's
> >>hearts to expect for people to just be technical about them. I use
> >>those three algorithms because some people "understand", md5 and not
> >>sha###sum. I mean, you may get some legacy data with their md5sum but
> >>the maintainers of the data may not be around. Once I found an rsync
> >>log that included the CRC signatures, that is why I include these
> >>kinds fo algorithms.
> >
> > Sorry, still makes no sense and is a waste of time. You're creating new
> > hashes right now, it doesn't matter if someone else might have made some
> > other hash some other time.
> 
>  But how could you have some assurance that that data relates to what
> their users thought of to be?

You can't. That's not what CRCs are for. They're not cryptographic,
so they are useless for any type of assurance that the data is intact.
Anyone modifying the data merely has to recalculate a new CRC and
substitute is for the original.

CRCs are a quick check on data segments when you're transmitting
segments of a file. If a CRC doesn't agree with its segment, you
ask for its retransmission. At the end of the transfer, you might
do a final CRC check on the whole file, for speed, but it would
be pointless to keep the number, as compared with checking the
file's MD5/SHAnnn digest if that had been archived. That's why
md5sum and shaNNNsum have a -c option.

Cheers,
David.

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#227524

David Wright writes:

> On Tue 29 Sep 2020 at 15:50:35 (+0200), Albretch Mueller wrote:
>>  But how could you have some assurance that that data relates to what
>> their users thought of to be?
>
> You can't. That's not what CRCs are for. They're not cryptographic,
> so they are useless for any type of assurance that the data is intact.

More precisely, hashes that are not cryptographic-grade are useless for
assurance that the data has not been modified by a third-party.  They
can still be useful for assurance that data has not been altered by wire
issues and other physical (non-human) issues.

--
Fabrice BAUZAC-STEHLY
PGP 015AE9B25DCB0511D200A75DE5674DEA514C891D

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#227349

[Multipart message — attachments visible in raw view] — view raw

On Vi, 25 sep 20, 13:49:25, Albretch Mueller wrote:
> 
>  My thinking may (once again) be a bit unhinged, but I would use,
> e.g., crc because it internatlly used by rsync, which I also use in my
> code.

Just for the archives, rsync is using MD5, and only if you specify the 
--checksum option.

Still unclear why the algorithm used by rsync is relevant in any way...

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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