[PLUG] [Updates]PLUG meeting on 6th Oct. at 5pm @SICSR
Sunil Beta Baskar
betasam at gmail.com
Sat Oct 6 21:50:23 PDT 2012
On 5 October 2012 00:06, Manjusha Joshi <manjusha.joshi at gmail.com> wrote:
> 1. There will be talk by Hitesh Wadekar on Openstack.
[ Query on VLAN ]
On the query of VLAN by Hitesh towards the end of the session, I
promised to reply to the mailing-list. Here it is.
802.1q and 802.1d permit only 12-bit fields as a standard, hence the
strict implementation of VLAN is restrictive to 2^12 bits (4095 unique
Strictly speaking this is VLAN ID [4-bit] + VLAN Unique ID [12-bit]
which would keep it 16-bit wide.
linux/drivers/net/macvlan.c has the 802.1q/d standard that has
limitations to 12-bits.
linux/drivers/net/vxlan.c has the 24-bit Cisco/Broadcom support tag
extension - effectively 2^24 - that's exactly (4096)^2
This is on the linux 3.5.5 and the 3.6 tree and the linux-next tree.
The vxlan.c is still version 0.1 (early), but is intended for
OpenStack and Cloud Servers.
[ SetUID bit ]
Behavior on linux-kernel 3.2.x with
$ chmod a+s somefolder
$ ls -ltr somefolder
shows all files inside somefolder with their original rights and
*owners* on ext4. This is on Debian Wheezy.
Although the setUID bit is still used, it is not recommended if you
want to have any sense of security on a system.
Hope this helps,
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