Wikipedia:Reference desk/Archives/Computing/2008 September 30

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September 30

Help understanding SSH command

ssh -D 8080 -C -q username@domain.com

I'm using the above command to access my home network via my web browser while I'm away at university. There are many other people on this local network -- what's to stop them from connecting to {my.local.ip.address}:8080 and thus having access to my personal home network? I trust that when used as just a secure shell SSH is completely safe, but since I have explicitly asked it to do this, doesn't that negate its in-built security? Apologies if this question seems a bit redundant to the more experienced computer users out there, but I want to make sure, just in case.

Thanks. —Preceding unsigned comment added by 131.111.243.37 (talk) 02:25, 30 September 2008 (UTC)

Just because you are using a different port does not make it less secure. The security is in the encrypted traffic between the two computers and the password you use when you login. So, I may be able to try and SSH into your computer on port 8080, but without knowing your password, there is nothing I can do. You aren't using "password" as your password, are you? -- kainaw™ 02:54, 30 September 2008 (UTC)

The -D option makes the SSH client listen as a SOCKS proxy on that port on the client computer and forward connections through the SSH directly to the other side. So the OP has a legitimate concern that if his computer is now listening on that port to allow his applications to use it, other people might be able to use it too. --Spoon! (talk) 04:41, 30 September 2008 (UTC)

The answer is that, by default, the SSH client only listens for port forwarding connections on the localhost, and so only programs from your own computer can use it. There is a setting in ssh_config called "GatewayPorts" (see the ssh_config(5) man page) which if enabled allows remote hosts to connect to forwarded ports too; but this option is disabled by default. --Spoon! (talk) 04:41, 30 September 2008 (UTC)

Thank you; that's exactly what I was concerned about, and it's good to know I have nothing to worry about. —Preceding unsigned comment added by 131.111.243.37 (talk) 09:53, 30 September 2008 (UTC)

Don't do this on a multi-user system, though. If someone else can log onto the same computer as you're using, they can also connect to that port. —Ilmari Karonen (talk) 18:42, 2 October 2008 (UTC)

Run a command at startup

Hello, I am running PCLinuxOS inside Virtual Box and I want to automatically mount the shared folder at startup because I don't want to run the command mount -t vboxsf vmshared /mnt/share everytime I start the VM.

I also have Ubuntu in VBox. In Ubuntu all I did was created this script in my home partition and added the line /home/abhishek/mount.sh to the end of the file /etc/rc.local and it worked. But this is not working in PCLinuxOS. Is there something I'm doing wrong or any other alternative method to do this? Thanks -Abhishek ^{Talk |Contribs} 10:42, 30 September 2008 (UTC)

Oh and I also made the script executable with chmod a+x -Abhishek ^{Talk |Contribs} 10:42, 30 September 2008 (UTC)

The normal way of mounting a given filesystem on system startup is to add the appropriate entry to /etc/fstab (see man -S 5 fstab). This is not recommended for network filesystems (as the network being down or the remote filesystem's provider being off makes your bootup hang) - but if in this case the thing you're mounting is really on the same physical computer (presumably its an fs on the hosting OS) then this is generally safe enough. -- Finlay McWalter | Talk 15:29, 30 September 2008 (UTC)

I agree - it would be very tricky to put the mount command into an auto-start setup because the UNIX/Linux autostart mechanism is complicated - when in the startup sequence do you want your command to run? Presumably after the networking system is up and running - but before the program pops up the "LOGIN:" screen. That's why you do it in the /etc/fstab - it's guaranteed to do this stuff at the appropriate time. You can avoid your machine hanging when a networked file system won't automount - you make it a 'soft' mount instead of a hard one. That results in the mount command for the soft-mounted partition being backgrounded if it doesn't pop up immediately. You can specify a timeout and a number of retries too - the information about that is also in the 'mount' manual page. SteveBaker (talk) 00:47, 1 October 2008 (UTC)

Error message

Request: GET http://en.wikipedia.org/wiki/WLOW, from 198.85.212.10 via sq35.wikimedia.org (squid/2.6.STABLE21) to () Error: ERR_CANNOT_FORWARD, errno (11) Resource temporarily unavailable at Tue, 30 Sep 2008 14:11:26 GMTVchimpanzee · talk · contributions · 14:33, 30 September 2008 (UTC)

Whatever caused this, try it again. Wikipedia often hiccoughs but usually does something right next time. If this isn't the case, please expalin what you were trying to do. -- SGBailey (talk) 15:05, 30 September 2008 (UTC)

I forgot to come here later in the day, but I posted as soon as it worked. I had been trying for several minutes just to post and couldn't. Perhaps I should have said something about thatVchimpanzee · talk · contributions · 15:48, 1 October 2008 (UTC).

Itunes

Is there a way I can switch back to the older version of itunes? —Preceding unsigned comment added by 64.119.61.7 (talk) 23:51, 30 September 2008 (UTC)

Try oldversion.com - or put it in google (http://www.google.co.uk/search?hl=en&q=old+version&meta=) 194.221.133.226 (talk) 08:17, 1 October 2008 (UTC)