Category Archives: OS

Xcompile RPI Kernel on Debian

Building an RPI 3.6.11 kernel with PPS support on GPIO pin 24.

Straight forward instructions with no BS and no fancy crap.

PSA: To people writing how-to’s, keep your shiny Linux CLI kung-fu on your resume and off your blog.

If you are interested in compiling a custom kernel for other reasons just skip/replace the PPS specific junk below.

Install Debian.

Add Emdebian to sources.list:

# Xcompile Toolchain
deb squeeze main

Install the packages we need:

apt-get install emdebian-archive-keyring
apt-get install gcc-4.4-arm-linux-gnueabi

Create directories for your build:

mkdir /admin
mount /admin

Email Server Attack

Type: Brute Force
Protocol: POP3
OS: Linux 3.6.11+ armv6l
Platform: Pi Rev. B
Memory: 512M
Daemon: Dovecot 2.1.7-7
Backend Daemon: MySQL 5.5
Backend OS: Linux 2.6.32-5-amd64
Backend Platform: Generic AMD A4-3400 APU Dual Core
Backend Memory: 3.5G
Total Attempts: 13356
Avg. Attempt/s: 2.71

Postmortem: was *unable* to successfully authenticate to any valid user.
Attack was mitigated at the firewall (DROP). was contacted about this event.

Debian Jumbo Frames

2 NAS servers both with 802.3ad bonded gigE nics based on the Realtek 8169 chip.
The highest MTU I could set was 7000 even though the D-Link DGS-1210-24 Rev. A switch can support up to 10k.

Below is just a single sample, but all tests stayed within 57x Mbits for MTU=1500 and 77xMbits for MTU=7000.

The important bits.
iperf was used for this testing.

MTU 1500:
[ 3] 0.0-10.0 sec 687 MBytes 576 Mbits/sec

MTU 7000:
[ 3] 0.0-10.0 sec 926 MBytes 777 Mbits/sec

Pi GPPS Clocks

Use Chris’ PPS kernel (until I have time or am compelled to compile my own).

Compile ntp 4.2.6p5 as follows (from aquarat):
But first: apt-get install libcap-dev

./configure --enable-ATOM --enable-NMEA --enable-linuxcaps; make; make install

Disable TTY on /dev/AMA0 in /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

Set baud rate in /boot/config.txt

Disable GPU sdram pause
# Disable GPU sdram mem pause

Comment out getty in /etc/inittab:

#Spawn a getty on Raspberry Pi serial line
#T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

Add pps-gpio to /etc/modules

Useless SNMPD Logging Debian

I found a blurb about ridding my logs of those useless “Connection from UDP” messages in my log files.
Why this isn’t the default I can only imagine (some will claim security I’m sure).

Here’s what I got out of it. That the below settings, added to /etc/default/snmpd will get rid of the useless messages but still log error messages.

SNMPDOPTS='-LS 0-4 d -Lf /dev/null -p /var/run/'

I restarted snmpd and it seems to function as expected.