linux

Ubuntu 11 on Kingston SV100S2/256G SSD

Here are some notes about my attempt to install Ubuntu 11 on Kingston SV100S2/256G SSD (on Dell Latitude E6510 laptop). Just in case somebody else finds it useful.

I have Googled around for information about SSD disk optimization for Linux and found that there are two main things to consider: partition alignment and filesystem options.

It appears to be important to (try to) align disk writes by the boundaries of SDD erase block size. This [1] article talks about LVM volumes alignment.

Self-encrypting (FDE) Hard Disks & Linux

Recently I have upgraded to Dell Latitude E6510 with 4 cores / 8 threads processor, plenty of RAM, and a fast hard disk. Nevertheless, the interactive performance of Ubuntu becomes sloppy beyond any measure when a virtual machine or two start trashing the disks.

There seems to be known performance problems in Linux kernel, like Bug 12309. And full disk encryption makes things even worse. It appears that new FDE technology will give laptop users a chance to move the burden of encryption to hard drives.

Linux Routing Quirks

Recently I have spent some time trying to mess up a routing table of Linux appliance to trick it into leaking out certain network traffic I was interested in. In theory it looked reasonably simple, but not quite so in practice. While trying to screw up the appliance I have learned a couple of new things about Linux networking:

Capstats: fast NIC statistics reporting tool

Just came across a nice tool to display NIC statistics, it is called capstats. Capstats is much less CPU intensive that iptraf, so it can be run along with hping3 to monitor its performance.

Example from capstats's website:
>capstats -i nve0 -I 1
1186620936.890567 pkts=12747 kpps=12.6 kbytes=10807 mbps=87.5 nic_pkts=12822 nic_drops=0 u=960 t=11705 i=58 o=24 nonip=0
1186620937.901490 pkts=13558 kpps=13.4 kbytes=11329 mbps=91.8 nic_pkts=13613 nic_drops=0 u=1795 t=24339 i=119 o=52 nonip=0

Making Linux network bridge transparent for 802.1x packets

Update 17/01/2011: If you are interested in 802.1x bridging, have a look at my Tapping 802.1x Links with Marvin blog post.

802.1x authentication messages are sent in Ethernet frames with destination MAC address set to 01:80:C2:00:00:03. This address belongs to “IEEE 802.1D MAC Bridge Filtered MAC Group Addresses” (01:80:C2:00:00:00 to 01:80:C2:00:00:0F) and such frames are not supposed to be relayed by bridges conforming to IEEE 802.1D [2]. For a number of reasons, you may want these frames to go through your bridge.

Transparent Connection Interception Trick

Now when I have a blog for half a year I figured I should post something. So here goes description of using Linux (Ubuntu in my case) bridge configured to redirect selected TCP connections to intercepting proxy (Burp) and while letting the intercepting proxy communicate with the server. Quite useful when doing pentests of fat clients and appliances communicating over HTTP(S), especially in a situation when you can't tamper with client's /etc/hosts file or use other technique to redirect interesting traffic.

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