--
Transfer your SSH public key to another host:
-% ssh-keygen # if you don't have a key yet
+% ssh-keygen # ssh-keygen / ssh-key-gen: if you don't have a key yet
[...]
% ssh-copy-id -i ~/.ssh/id_rsa.pub user@remote-system
or
Bus 004 Device 008: ID 1199:6813 Sierra Wireless, Inc.
# modprobe usbserial vendor=0x1199 product=0x6813
+
+To get a list of available providers execute:
+
+# gcom -s -d /dev/ttyUSB0 /usr/share/doc/gcom/examples/operator
--
hdparm - get/set hard disk parameters
--
Debugging SSL communications:
-% openssl s_client -connect server.adress:993
+% openssl s_client -connect server.adress:993 > output_file
+% openssl x509 -noout -text -in output_file
or
# sh /usr/share/doc/grml-terminalserver/examples/create-netboot
--
+To boot grml via network (PXE) check out grml-terminalserver:
+
+# grml-terminalserver
+
+See http://grml.org/terminalserver/ for more details.
+--
Rotate pictures:
Using the 'Orientation' tag of the Exif header, rotate
or manually remove the entry from /etc/modprobe.d/grml.
--
+Create a Debian package of a perl module:
+
+% dh-make-perl --cpan Acme::Smirch --build
+--
+The Magic SysRq Keys (SysReq or Sys Req, short for System Request):
+
+To reboot your system using the SysRq keys just hold down the Alt and
+SysRq (Print Screen) key while pressing the keys REISUB ("Raising
+Elephants Is So Utterly Boring").
+
+R = take the keyboard out of raw mode
+E = terminates all processes (except init)
+I = kills all processes (except init)
+S = synchronizes the disk(s)
+U = remounts all filesystems read-only
+B = reboot the system
+
+Notice: use O instead of B for poweroff.
+
+Or write the sequence to /proc/sysrq-trigger instead:
+
+# for i in r e i s u b ; do echo $i > /proc/sysrq-trigger ; done
+
+To enable or disable SysRq calls:
+
+# echo 0 > /proc/sys/kernel/sysrq
+# echo 1 > /proc/sys/kernel/sysrq
+
+See http://en.wikipedia.org/wiki/Magic_SysRq_key for more details.
+--
+Memtest / memcheck:
+
+Just boot your grml Live-CD with "memtest" to execute a memcheck/memtest
+with Memtest86+.
+--
+Tunnel TCP-Traffic through DNS using dns2tcp:
+
+Server-side:
+~~~~~~~~~~~~
+1. Create necessary DNS-Records:
+dnstun.example.com. 3600 IN NS host.example.com.
+dnstun.example.com. 3600 IN A 192.168.1.1
+host.example.com. 3600 IN A 192.168.1.1
+
+2. Configure dns2tcpd on host.example.com.:
+# cat /etc/dns2tcpd.conf
+listen = 192.168.1.1 #the ip dns2tcpd should listen on
+port = 53 #" port " " " "
+user = nobody
+chroot = /tmp
+domain = dnstun.example.com. # the zone as specified inside dns
+ressources = ssh:127.0.0.1:22 # available resources
+
+3. Start the daemon:
+# cat > /etc/default/dns2tcp << EOF
+# Set ENABLED to 1 if you want the init script to start dns2tcpd.
+ENABLED=1
+USER=nobody
+EOF
+# /etc/init.d/dns2tcp start
+
+Client-side:
+~~~~~~~~~~~~
+You have two possibilities:
+- Use the DNS inside your network (DNS must allow resolving for external domains)
+# grep nameserver /etc/resolv.conf
+nameserver 172.16.42.1
+# dns2tcpc -z dnstun.example.com 172.16.42.1
+Available connection(s) :
+ ssh
+# dns2tcpc -r ssh -l 2222 -z dnstun.example.com 172.16.42.1 &
+Listening on port : 2222
+# ssh localhost -p 2222
+user@host.example.com:~#
+
+- Directly contact the endpoint (port 53 UDP must be allowed outgoing)
+# dns2tcpc -z dnstun.example.com dnstun.example.com
+Available connection(s) :
+ ssh
+# dns2tcpc -r ssh -l 2222 -z dnstun.example.com dnstun.example.com &
+Listenning on port : 2222
+# ssh localhost -p 2222
+user@host.example.com:~#
+
+Notice: using 'ssh -D 8080 ..' you will get a socks5-proxy listening on
+localhost:8080 which you can use to tunnel everything through your "dns-uplink".
+--
+Configure a MadWifi device for adhoc mode:
+
+Disable the autocreation of athX devices:
+# echo "options ath_pci autocreate=none" > /etc/modprobe.d/madwifi
+
+Remove the autocreated device for now:
+# wlanconfig ath0 destroy
+
+Configuration in /etc/network/interfaces:
+
+iface ath0 inet static
+ madwifi-base wifi0
+ madwifi-mode adhoc
+ ...
+
+Hints:
+ - Do not use interface names without ending 0 (otherwise startup fails).
+ - Only chooss unique names for interfaces.
+--
+Find dangling symlinks using zsh:
+
+% ls **/*(-@)
+--
+Use approx with runit supervision
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Install the packages:
+# apt-get install approx runit
+
+Add user approxlog for the logging daemon:
+# adduser --system --home /nonexistent --no-create-home approxlog
+
+Create config directory:
+# mkdir /etc/sv/approx
+
+Use /var/run/sv.approx as supervise directory:
+# ln -s /var/run/sv.approx /etc/sv/approx/supervise
+
+# cat > /etc/sv/approx/run << EOF
+#!/bin/sh
+echo 'approx starting'
+exec approx -f 2>&1
+EOF
+
+You normally do not need a logging service for approx because it logs
+to syslog too. So just for completion:
+# mkdir -p /etc/sv/approx/log
+# ln -s /var/run/sv.approx.log /etc/sv/approx/log/supervise
+# cat > /etc/sv/approx/log/run << EOF
+#!/bin/sh
+set -e
+LOG="/var/log/approx"
+test -d "$LOG" || mkdir -p -m2750 "$LOG" && chown approxlog:adm "$LOG"
+exec chpst -uapproxlog svlogd -tt -v "$LOG"
+EOF
+
+Now activate the new approx service (will be started within 5s):
+# ln -s /etc/sv/approx/ /var/service/
+
+Make approx managed via runit available via init-script interface:
+# dpkg-divert --local --rename /etc/init.d/approx
+# ln -s /usr/bin/sv /etc/init.d/approx
+--
+Remote-reboot a grml system using SysRQ via /proc (execute as root):
+
+eject &>/dev/null
+umount -l /cdrom
+eject /dev/cdrom
+echo b > /proc/sysrq-trigger
+--
+Show what happens on /dev/sda0:
+
+# mount the debugfs to relay kernel info to userspace
+mount -t debugfs none /sys/kernel/debug
+
+# is a convenient wrapper arround blktrace and blkparse
+btrace /dev/sda0
+--
+Convert Flash to Avi:
+
+% ffmpeg -i input.flv output.avi
+--
+Usage example for cryptsetup / -luks encrypted partition on LVM:
+
+volume group name: x61
+logical volume name: home
+
+echo "grml-crypt_home /dev/mapper/x61-home none luks" >> /etc/crypttab
+Start cryptdisks
+mount /dev/mapper/grml-crypt_home /mnt/test
+--
+fdisk/parted/... complains with something like
+'unable to open /dev/sda - unrecognised disk label'?!
+
+See http://grml.org/faq/#fdisk =>
+
+* use /sbin/fdisk.distrib from util-linux
+* switch to sfdisk, cfdisk,...
+* use parted's mklabel command (but please read the
+ parted manual before executing this command)
+--
projects / grml-tips.git / blobdiff