Subject: Re: netfilter/iptables and network interface names

From: Patrick McHardy <[email-masked]>
Date: Thu, 04 Feb 2010 15:55:55 +0100

Jan Engelhardt wrote:
> On Thursday 2010-02-04 15:31, Patrick McHardy wrote:
>> Jan Engelhardt wrote:
>>> On Thursday 2010-02-04 13:58, Thomas Woerner wrote:
>>>
>>>> I think there should be some discussion about interface names and
>>>> limits in kernel and netfilter/iptables.
>>>>
>>>> What do you think?
> 
> When was the last time you needed a control character in your
> interface name?

Actually I did use ansi-colors in my interface names once for fun :)

Anyways, I don't see why iptables should impose arbitrary restrictions.

>>> I think we should cc netdev for a start.
>> I don't think there is a reason for this limitation in iptables,
>> so why not simply remove it?
> 
> Like this?
> 
> @@ -473,12 +473,11 @@ void xtables_parse_interface(const char *arg, char *vianame,
>  		memset(mask, 0xFF, vialen + 1);
>  		memset(mask + vialen + 1, 0, IFNAMSIZ - vialen - 1);
>  		for (i = 0; vianame[i]; i++) {
> -			if (vianame[i] == ':' ||
> -			    vianame[i] == '!' ||
> -			    vianame[i] == '*') {
> +			if (vianame[i] == '/' ||
> +			    vianame[i] == ' ') {
>  				fprintf(stderr,
>  					"Warning: weird character in interface"
> -					" `%s' (No aliases, :, ! or *).\n",
> +					" `%s' ('/' and ' ' are not allowed by the kernel).\n",
>  					vianame);

The kernel also forbids ".".