postfix with no local delivery 
All mails for local accounts should be transfered to a central mailserver.

Sender email should look like USER@HOST.DOMAIN and all mails should be delivered to root@DOMAIN.

Usually /etc/aliases is used, but in my case local delivery is disasbled.

/etc/postfix/main.cf:
myhostname = HOST.DOMAIN
myorigin = $myhostname
relayhost = $mydomain
mydestination =
local_recipient_maps =
inet_interfaces = 127.0.0.1
local_transport = error:local delivery is disabled
recipient_canonical_maps = hash:/etc/postfix/recipient_canonical

/etc/postfix/recipient_canonical:
@HOST.DOMAIN root@DOMAIN


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script to rescue/backup a system and restore from a cd with initramfs 
Searching for a rescue system that creates a bootable CD to restore my system i found mkcdrec. Because sometimes things (mkcdrec/debian/ubuntu) changes and i had to test and patch for new mkcdrec versions, so i droped it.

Then i started to make a live CD with debian-live and make my install script by myself. I also dropped it (long boottime and had too much to hack to let it work like i wanted).

Now i had the idea to build my own script that tar's my system and builds a bootable cd. I liked the idea of initramfs to extend it like i will and it boots much faster. The only drawback is that all things are hardcoded and have to be changed for every system i backup. But its only a single script: Read More...

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qemu 
#> sudo apt-get install kqemu-source kqemu-common build-essential
#> sudo module-assistant prepare kqemu
#> sudo module-assistant auto-install kqemu

/etc/udev/rules.d/60-kqemu.rules:
KERNEL=="kqemu", NAME="%k", MODE="0660", GROUP="kqemu"

#> sudo addgroup --system kqemu
#> sudo adduser USERNAME kqemu
#> modprobe kqemu

create a qemu image:
#> qemu-img create -f qcow2 root.qcow2 20G

install with a cd:
#> qemu -hda root.qcow2 -cdrom cd.iso -boot d

boot installed system:
#> qemu -hda root.qcow2


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fast sftp 
sftp -o Ciphers=blowfish-cbc USER@HOST

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packet capture with ssh and tcpdump on a remote host and display with wireshark 
#> mkfifo /tmp/shark
#> ssh USER@HOST 'sudo tcpdump -i eth0 -w - -p -n -s 0' > /tmp/shark

In an other session
#> wireshark -k -i /tmp/shark

Then go back to first session and enter the ssh password.

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