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I want to tar to a remote host using the remote host's IPv6 address. I can ssh and scp to the host but GNU tar does not accept the IPv6 address.

I tried:

tar -cjvf root@2001:DB8::1234:5678:/backup.tar.bz2 *

and

tar -cjvf root@[2001:DB8::1234:5678]:/backup.tar.bz2 *

and

tar -cjvf root@\[2001:DB8::1234:5678\]:/backup.tar.bz2 *

but none of these work. All of these give address errors from tar. My Ubuntu system has tar version 1.25-3.

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This is likely a depreciated feature in GNU tar, and is not caused by IPv6 at all. Can you please provide a screenshot which shows that root@host:/path will work for IPv4 hosts? Also, instead of just showing us the command which you used, please show the command and the errors and output. – Stefan Lasiewski Jul 26 '12 at 1:21
Also, you might be looking for --rsh-command=/path/to/ssh, which is vaguely hinted at linux.die.net/man/1/tar . – Stefan Lasiewski Jul 26 '12 at 1:22
I haven't see anything in the GNU docs that describes this feature as depreciated and it does work for IPv4 (you can easily try both IPv4 and IPv6).Yes, I should have included the error output which has tar complaining about that it couldn't write that device. The --rsh-command is not needed since GNU tar on CentOS/Ubuntu is compiled to automatically use ssh instead of rsh and this wouldn't affect the destination IP. – Lars Nordin Aug 10 '12 at 14:42

3 Answers

up vote 8 down vote

Since it works over SSH, you can use:

tar cjvf - /folder/to/backup | ssh root@ipv6 "cat > data.tar.bz2"
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1  
Remember to add -e none to ssh, otherwise some bytes may get corrupted. – Thor Jul 24 '12 at 12:31
3  
The tar pipe won't allocate a pty, so -e option doesn't apply (I tested using the default ~ and -e a and it wouldn't treat either as an escape character). – Jay Jul 24 '12 at 12:46
You're right, I didn't know that, thank you. – Thor Jul 24 '12 at 12:56
I tried running cat in the ssh remote command but I got write errors. I was able to get the command working by using dd instead of cat. – Lars Nordin Sep 12 '12 at 18:22
up vote 2 down vote

I think you're imputing powers to tar that it doesn't actually have. No version of tar to which I have immediate access suggests that the -f flag takes an argument which is a remote user/machine pair.

Could you say why you think this will work?

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It does work for GNU tar but not AT&T or older BSD tar - it makes use of the BSD rsh (but uses ssh) and rmt system. See the bottom of this page: gnu.org/software/tar/manual/html_node/file.html#SEC104 – Lars Nordin Jul 24 '12 at 13:07
But as the bottom of that page says, "The remote host is accessed using the rsh program, with a username of user". I'm delighted to learn about the ability to auto-access a remote machine (thank you!), but I don't know anyone who's permitted rsh in a donkey's age. It certainly mentions nothing about being willing to use ssh as a transport mechanism. – MadHatter Jul 24 '12 at 13:13
up vote 1 down vote accepted

I found the answer (actually already had the answer before asking but figured this would help others and I did learn something). Breaking the tar and ssh into two different steps worked.

tar cvjf - * | ssh root@2001:DB8::1234:5678 "dd of=/backup/backup.tar.bz2"

Note: I tried using cat instead of dd but cat did not work for me - tar gave write errors. May be if I was using ssh key authentication instead of password it would have worked.

Reference:

http://www.astrouw.edu.pl/~jskowron/tar-ssh/

http://www.cyberciti.biz/faq/howto-use-tar-command-through-network-over-ssh-session/

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