Make a PC Look Like a Firewire or USB Drive?

buckinm asks: "Here's the problem: I have a Windows laptop that I use for work. When I'm at home though, I much rather use my Mac. Since we use Cisco's VPN client at work, I can't mount the drives on the PC from the Mac. What I'd like to know, is there any software out there that would make the PC act like a Firewire or USB drive? I'd want to be able to mount it read/write. I know I could do some sort of rsync of thing when not connected to the VPN, but that seems like too much trouble. I wouldn't be against writing something like that, if I could get some idea of what is required to listen / respond to traffic on the Firewire or USB ports."

Comments

Mac Mini Killer!

[musselm]

At first glance I thought this was an article about cramming PC parts into a Firewire drive enclosure, along the lines of the stories that proliferated after the release of the Mac Mini:)

Possible, I think

[MBCook]

I see no reason that it shouldn't be possible. Macs can do this. You boot them while holding "F" or "D" or "Command-F" or "Command-D" or something. They sit there and act like a firewire disk. I think you can even access the CD drive in them.

As for the PC side, I don't know. It's obviously possible, but I haven't heard of it. The Tinkerer in me says make a switch that disconnects the HD from the computer and connects it to a IDE->Firewire adaptor you hide in the case. Switch in one position it's a normal computer. Switch in the other it's a firewire disk.

Good luck.

Re:Possible, I think

[nuxx]

For what it's worth, you hold T and it puts it in 'T'arget disk mode. This is so damn handy for when you've got a b0rked OS install, but you want to recover the data. It's so much easier than pulling the disk and sticking it in an external enclosure, especially in laptops...

Re:Possible, I think

[Joseph Vigneau]

The only reason Apple can giveyou cool features like that is because they have a tight control of their systems.

What's stopping an x86 motherboard manufacturer from providing the exact same feature? I would hope they have tight control of their systems, too.

Re:Possible, I think

[Ster]

Actually, the kernel isn't involved at all. It's all done in OpenFirmware.

Back when PowerBooks used SCSI, it turned the 'Book into a SCSI drive. I believe there was a Control Panel you could use that would set the SCSI ID that it would use.

It's not just for PowerBooks anymore, though. Any[*] Mac with built-in FireWire can do Target Disk Mode.

[*] I'm pretty sure it's "Any", but it might just be "Most". Certainly works for old "Sawtooth" PowerMac G4s on up, and iMac DVs on up, in addition to the laptops.

-Ster

Re:Possible, I think

[Joseph Vigneau]

Because the motherboard manufacturer's only control the motherboard, and in some cases either the video card or the CPU, not the memory, hard drive, sound card, TV tuner card, Firewire card, network card or pretty much anything else that Apple keeps tightly under their control.

More and more motherboards have this stuff on board, particularly Firewire and USB controllers. With a smarter BIOS (maybe even LinuxBIOS), those manufacturers could provide a service similar to Apple's Target Disk Mode.

FWIW, Apple doesn't have tight control over drives and memory; these are commonly swapped out with commodity parts with higher capacity by end users.

And, as someone else mentioned here, there's at least one PC laptop manufacturer that has this feature.

ive only used firewire 3 times in my life but...

[ForestGrump]

the firewire interface has a tcp/ip stack.

You'll want ....

[Muad'Dave]

...the gadget device driver and API. From the linked page:

The API makes it easy for peripherals and other devices embedding GNU/Linux system software to act in the USB "device" (slave) role. The drivers implementing and using that API combine to make a useful driver framework for Linux systems that implement USB peripherals.

Re:You'll want ....

[enigmatichmachine]

firewire != USB.
mac fanboys: yes, firewire drive mode is great, but has nothing to do with this problem. he wants a way to access the files over USB. I looked into it myself when i had a bad case of mac envy, but usb is a master/slave model, devices are classified either as masters, or slaves, not both, and as far as i know, 2 of the same type are not able to communice via the usb protocol. it looks like the above poster has software to allow a server to emulate a slave device, but firwire is more of a peer to peer technology, and any device can issue command to any other device, which is why it can implement tcp-ip over it.

p.s. i wish USB were more like firewire, as i've always wanted my pda's (palm or ppc) to be able to use other slave usb devices (really just joysticks) but alas...

Re:Simplest way:

[wowbagger]

This probably WON'T work, for the same reason he cannot use Samba over normal Ethernet.

Most VPN clients, in order to protect the network you are VPN'ing into, will shut down all other connections - they set the VPN interface to be the default route, and then they remove any other routes.

So doing IP over Firewire will work, right up to the time the VPN client kills it.

I'd suggest finding a small Linksys/Dlink (but NOT BELKIN) router that has Cisco VPN client support - the router will handle the VPN, and you can plug both your Mac and your PC into it.

Re:Make sense man!!

[hawkstone]

> You want to mount drives form a Mac?
> Share the drives and mount them.

He can't, because VPN usually shuts off the other network connections.

> You want to mount vpn mapped drives from a Mac?
> Same deal, share them and mount them. If you can't share them, them subst them and share the subst.

Sharing won't work at all over TCP/IP while VPN is in use.


> You want to access your network from the Mac via the laptop?
> Enable routing on the laptop.
> Better yet, why not install the VPN client on the Mac and leave the laptop out of the question?

He did install VPN on the Mac -- his data is on the Windows laptop.

> What do you want?

He wants to get at all his work data, which is on his work laptop, while using his home desktop machine to connect with his servers at work. Since he can't use a normal TCP/IP connection to have the two machines talk to each other, but they are both at home with him, he thought using USB or Firewire to connect them would avoid the issues with trying to share data between them while the Mac is hooked up to VPN.

Re:Simplest way:

[FreeLinux]

they set the VPN interface to be the default route, and then they remove any other routes.

Too true. and adding a host route or two resolves the issue.

route add mac'sIP mask 255.255.255.255 eth0'sIP

It may also be necessary to add a host route for the local eth0 interface as well, depends on how far your VPN client goes. I'd put it in a batch file so that I could run it each time I bring up the VPN.

Comment removed

[account_deleted]

Comment removed based on user account deletion

What problem are you trying to solve?

[kwerle]

Since we use Cisco's VPN client at work, I can't mount the drives on the PC from the Mac

OK, you have a PC laptop. You have a Cisco VPN. You have files. What files do you need to share?

If the files are on the laptop, just network the 2 boxes at home and share the files, right?

If the files are at work, get a Cisco VPN solution for the Mac (I used one for years).

If IT won't help (surprise, right?), and you're determined to break the law/policy/whatever, there are a lot of options:

Add an interface on the laptop and set it up as a router.

http://sourceforge.net/projects/openvpn/, maybe over http://www.nocrew.org/software/httptunnel.html (either from the laptop or a machine in the office).

Maybe run the VPN in an emulator layer (http://fabrice.bellard.free.fr/qemu/), give it access to the local filesystem, let the "outter layer" windows export the same filesystem, keep updating using rsync (just brainstorming, here).

Or just keep it simple, stupid. Get an external firewire drive, dump the files you need, and swap it to/from the mac/laptop.

Re:What problem are you trying to solve?

[BridgeBum]

I think, perhaps, the person asking the question would like to be able to access the files on the PC and VPN simultaneously. He said he could do an rsync type thing prior to initiating the VPN, but that's too much work.

Given that many VPN solutions are configured to not allow split tunneling, you cannot access your local LAN IP addresses while connected via VPN. I believe the Cisco client by default disallows split tunnelling, but that may be a server side setting that is negotiated, I'm not 100% sure.

So, let's rephrase: How can I access the information on my PC without using IP?

Re:The windows laptop has a different disk format

[Jeremiah Cornelius]

OS X doesn't WRITE to NTFS! FAT32 - Yes.

You're making the Doctor happy/not happy.

Just use a Linux Live CD

[Taladar]

Use a Linux-Live-CD or USB-Boot or even Floppy to boot a minimal Linux with Samba, NFS or whatever fits your Mac best and share the files with that. Switching is as easy as removing the CD from the Drive and rebooting.

Networking via USB or Firewire probably won't help

[Curmudgeonlyoldbloke]

I looked into this a while back.
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8 &c2coff=1&threadm=79240318.0302052128.2ac4b7de%40p osting.google.com&rnum=8&prev=/groups%3Fq%3Dcisco% 2B%2522default%2Bgateway%2522%2Bvpn%2Bclient%26hl% 3Den%26lr%3D%26ie%3DUTF-8%26c2coff%3D1%26sa%3DN%26 tab%3Dwg
is a summary of what I found then.

There is an option "allow local LAN access" on the "transport" tab of the VPN client setup. However, according to the Usenet post above:

"... the administrator has the final say whether or not clients can do local LAN, both by enabling/or/ not enable "split tunnelling"
in the concentrator GROUP/CLIENT CONFIG. Without split tunnelling your stuck sending everything through the tunnel. You are only allowed to speak to your DEFAULT gateway, I.E the ISP ROUTER. Nothing you can do with the client will override this."

Re:Simplest way:

[bill_mcgonigle]

A Google search turned up this document that shows that the Cisco VPN client is cabable of split tunneling.

The AskSlashdotter needs to RTFM.

Re:Simplest way:

[Tintivilus]

adding a host route or two resolves the issue.

This likely won't work either... the Nortel client, for example, automatically disconnects if *any* routing table changes are made after the client connects. Makes it a real pain to use networked printers at home, too.

Same thing, for Pocket PCs?

[Kris_J]

Is there a program that will make my Pocket PC (Asus 716) behave like a normal USB drive so I can copy stuff on and off of it without needing the ActiveSync app installed?

Hack the damn thing

[JackAsh]

The Cisco client does some low level stuff that if I understand it correctly, actually installs a new low level IP stack under the OS's that you have no control over or access to. The OS's stack is fully under the control of the VPN client since all traffic has to pass through it's private stack. It's funny, you can't even ping your own defaut gateway, the one the VPN traffic is traveling through.

The way around it is to use another stack. IPX might work but the simplest one i've found the IPv6 stack. It's completely separate from the V4 stack and the Cisco client I've used doesn't touch it. You can use all kinds of fun tricks with that. Hmm... better post this as AC. We all know "freedom of speech" doesn't mean what it used to these days.

AC, you are absolutely right. This is exactly what he needs to do. I've done the IPX trick on the Cisco VPN client many times to print from my work laptop to my home printer (via a second windows box). I'm not sure about IPX support in the Mac (or even worse Netbios over IPX) so I'd go with the IPv6. A second trick that no longer works that well (used to work on older Cisco clients) was to add a second NIC (i.e. a PCMCIA 802.11 card) after the tunnel was established, or to have it deactivated at least, don't remember the exact details.

As a funny note, I notified Cisco of this problem with the Split Routing protection about 5 years ago (through the proper support channels, being as my company were customers of the product). They claimed it wasn't a bug or vulnerability.

Last but not least, you can always just go and get the damn VPN client for the Mac, and share the files the long way - over your tunnel into the office :).

-Jack Ash

FireWire? Likely. USB? I doubt it.

[veliath]

FireWire host-controllers in PCs are symmetric as far as I know, so you could theoretically have a PC behave like a FireWire drive (i.e. speak SBP2). The protocol itself is a form of RDMA - which means FireWire controllers export their hosts as addressable 48bit memory ranges. Should be symmetric.

USB host-controller in PCs are different. In USB, only the host-controller can bus-master - i.e. initiate transactions on the USB bus - no other device on the bus can. I believe this is specified in the protocol itself. The protocol allows for a smart host-controller and dumb devices. One master and the rest slaves.

This might become clearer if you examine the terminology. The ports closest to the host-controller are said to belong to the "root hub". USB provides for a tree architecture, rooted at the host-controller's ports.

This means that you cannot connect two PCs back-back through their USB ports and say run PPP over them. AFAIK host-controllers in PCs do not have a slave mode that they can be switched to.

The PC emulating a hard-disk has to be able to become a slave to show up as a device.

veliath

USB Bridge Cable Was What I Used

[WhyCause]

I needed to do this when I upgraded from an old Win98 desktop to my current WInXP laptop. The best solution (cost wise) that I found was a USB to USB bridge cable.

I purchased an IOgear Smartlink cable. I had to use USB 1.1 due to OS and hardware inadequacies, but there may be a USB 2.0 option (though I don't see it on the IOgear site). The connection software is pretty crummy-looking, but it works, and their site claims that it supports Macs as well Windows (although I have not used it on a Mac). Since it's USB 1.1, it is as slow as molassass for entire-drive transfers, and you may prefer a different method.

Another option I looked into was an ethernet crossover cable, which, I believe swaps two of the wires over the course of the cable run. This was available at RadioShack (and I am sure other places). I decided not to go down this route, and it sounds like a no go for you as well, but I'm including it for the sake of completeness.

The third thing that might work is an external harddrive. I didn't use one because of the expense, but it may be worth it if you don't want to wait while your files transfer via USB. If you're doing smallish (less than 1GB) transfers, a thumb-drive may be the easiest way to do this.

It is VERY important that you do not try a straight USB to USB connection without the bridge cable. I understand that it can fry the USB ports on the machines. If you look at the image of the Smartlink cable on the page linked above, you'll see a bulge in the middle of the cable. That's the USB 'slave' that allows both computers to act as masters when doing the file transfer. FireWire may be a different story though, as you may just be able to plug it right in (no guarantees, though).