Re: [Openvpn-devel] --dev and --dev-name under linux 2.4+

[Christian L. <lad...@zl...>]

On Tue, 3 Jun 2003 01:36:55 -0000
"James Yonan" <ji...@yo...> wrote:

Hi, James,

I wrote this --dev-name - patch. I'm sorry, if I oversaw the interference with --dev.

What I need is the posibility to group my different openvpn-interfaces by name,
so I can assign firewall-rules more generally using wildcards for interface-names
(like "iptables --in-interface office+ ..." or "... --in-interface customer+").

If --dev renames the interfaces (--dev "office01" or --dev "customer4711"), that
perfectly fits my needs.

Thank you for your great software!

Regards, Christian.

> A debian bug report was submitted that inspired me to look deeper into the
> operation of --dev and the new --dev-name flag.
> 
> --dev-name was a patch for tun.c which I received a few months ago, which only
> really does anything for linux 2.4.  On first glance it appeared nominally
> useful, so I merged it, but on further inspection it appears to be mostly
> redundant with --dev.
> 
> It appears that the motivation for implementing --dev-name was that --dev
> assumes its argument is either "tun", "tap", "null", or tun/tap with a unit
> number (e.g. "tun4").  But --dev is limited in that it doesn't allow arbitrary
> renaming.
> 
> In OpenVPN 1.3.2, if the --dev argument was larger than 3 chars, it was
> assumed that a unit number was present.  In 1.4.1 that test was changed so
> that an ascii digit needed to be present to assume a unit number.  If a unit
> number was present, then the name of the device (as it appears in ifconfig)
> would be changed to reflect the explicit unit number.  What I think probably
> inspired the debian bug report is that in 1.3.2 if you said "--dev foobar
> --dev-type tun", openvpn would have renamed the tun device to foobar, because
> foobar is > 3 characters.  In 1.4.1, no rename would occur because "foobar"
> doesn't contain any numerical digits.  In 1.4.1, you would need to say "--dev
> tun --dev-name foobar" to get the same effect.  This seems somewhat arbitrary
> and confusing.
> 
> My conclusion is that the implementation of --dev and --dev-name is mostly
> redundant because --dev can just as easily set the device name based on its
> argument, if that argument is something other than "tun", "tap", "null".  The
> current operation of "--dev tun" or "--dev tap" would be preserved so that a
> dynamic unit number would be allocated if, for example, "--dev tun4" is given.
>  But you could also specify "--dev foo --dev-type tun" and a tun device named
> foo would be created.
> 
> I've patched the current development release to remove --dev-name, and to
> allow --dev to set a specific device name as in the above paragraph.
> 
> Download:
> 
> http://openvpn.sourceforge.net/beta/openvpn-1.4.1.4.tar.gz (or CVS)
> 
> James
> 
> 
> 
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