usb modem dialin 
Wednesday, September 7, 2011, 16:04 - System, Network, Debian/Ubuntu
Posted by Administrator
Server

needed packages: mgetty, pppd

start and stop mgetty on plugin of usbmodem (0572:1329 Conexant Systems (Rockwell), Inc.)

/etc/init/mgetty.conf
# mgetty - dialin daemon

description     "mgetty daemon"

start on tty-device-added KERNEL=ttyACM0
stop on tty-device-removed KERNEL=ttyACM0

respawn
exec /sbin/mgetty -s 115200 -D /dev/ttyACM0

/etc/mgetty/login.config
/AutoPPP/ - a_ppp /usr/sbin/pppd auth +chap -pap name dialinserver remotename dialer debug

I use chap instead of pap because of plain password used by pap.

/etc/ppp/chap-secrets
dialer dialinserver password *

/etc/ppp/options.ttyACM0
10.0.0.1:10.0.0.2


Client

needed packages: pppd

/etc/ppp/peers/dialinserver
noauth
connect "/usr/sbin/chat -v -f /etc/chatscripts/dialinserver"
debug
/dev/ttyS0
115200
defaultroute
noipdefault
name dialer
remotename dialinserver

/etc/chatscripts/dialinserver
ABORT BUSY ABORT 'NO CARRIER' ABORT VOICE ABORT 'NO DIALTONE' ABORT 'NO DIAL TONE'
ABORT 'NO ANSWER' ABORT DELAYED
'' ATZ
OK-AT-OK "ATDTnumber"
CONNECT \d\c

/etc/ppp/chap-secrets
dialer dialinserver password *

Connect with "pon dialinserver" and disconnect with "poff dialinserver"

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route icmp to a different gateway 
Thursday, July 28, 2011, 16:17
Posted by Administrator
echo 100 icmp_route >> /etc/iproute2/rt_tables
ip rule add fwmark 1 table icmp_route
ip route add default via IP_OF_NOT_DEFAULT_GATEWAY dev eth0 table icmp_route

iptables -t mangle -A OUTPUT -d IP_TO_PING -p icmp -j MARK --set-mark 1


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USB: uss720 fixup refcount position 
Monday, March 28, 2011, 14:24 - Patches
Posted by Administrator
My testprog do a lot of bitbang - after hours i got following warning and my machine lockups:

WARNING: at /build/buildd/linux-2.6.38/lib/kref.c:34

After debugging uss720 driver i discovered that the completion callback was called before usb_submit_urb returns.
The callback frees the request structure that is krefed on return by usb_submit_urb.
--- a/drivers/usb/misc/uss720.c
+++ b/drivers/usb/misc/uss720.c
@@ -177,12 +177,11 @@ static struct uss720_async_request *submit_async_request(...
        spin_lock_irqsave(&priv->asynclock, flags);
        list_add_tail(&rq->asynclist, &priv->asynclist);
        spin_unlock_irqrestore(&priv->asynclock, flags);
+       kref_get(&rq->ref_count);
        ret = usb_submit_urb(rq->urb, mem_flags);
-       if (!ret) {
-               kref_get(&rq->ref_count);
+       if (!ret)
                return rq;
-       }
-       kref_put(&rq->ref_count, destroy_async);
+       destroy_async(&rq->ref_count);
        err("submit_async_request submit_urb failed with %d", ret);
        return NULL;
 }

http://git.kernel.org/?p=linux/kernel/g ... 5b45be8688

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fast reboot with kexec 
Friday, March 4, 2011, 15:15 - System, Debian/Ubuntu
Posted by Administrator
sudo apt-get install kexec-tools

change LOAD_KEXEC to true in /etc/default/kexec

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record a video with ffmpeg from a webcam with audio 
Monday, January 31, 2011, 18:49 - System
Posted by Administrator
First activate and rise webcam audio input level with alsamixer.

ffmpeg -f video4linux2 -i /dev/video0 -pix_fmt yuv420p -s vga -r 8 -f alsa -ac 1 -ar 16000 -i hw:1,0 -vcodec mpeg4 -b 400k -acodec libmp3lame -ab 80k video.avi

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