how to reassemble existing raid array with mdadm

# mdadm --assemble /dev/md5 /dev/sdc1 /dev/sde1

using memcache for php session

สรุป พอคนเข้าเว็บเยอะ php บน debian หรือ ubuntu ไปเรียกใช้ "fuser" ในการจัดการไฟล์ session ที่หมดอายุ ซึ่งมีประสิทธิภาพต่ำมาก ต้องเปลี่ยนไปใช้ memcache แทน ฉะนั้น ปัญหาจึงหาย และ จำไว้เป็นบทเรียน

a working iptables firewall rules

#!/bin/bash

# eth0 is connected to the Internet
# eth3 is network B

# flush all chains
iptables -F
# flush all chaines in nat table
iptables --table nat -F

# default policies
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
iptables -P INPUT DROP

# allow unlimited traffic on loopback
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

# {{{ packet forwarding
# allow packet forwarding for the entire LAN
iptables -A FORWARD -i eth3 -o eth3 -j ACCEPT # network B

# masquerade
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE

# allow packet forwarding from internal network to the internet
# and allow packet forwarding from the internet to internal network
# if the packet is established or related from the internal network
iptables -A FORWARD -i eth3 -j ACCEPT # network B
iptables -A FORWARD -i eth0 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# }}} packet forwarding

# ssh
iptables -A INPUT -i eth0 -p tcp -s external_ip_0,external_ip_1 --dport 22 \
  -j ACCEPT

# mosh
iptables -A INPUT -i eth0 -p udp -s external_ip_0,external_ip_2 \
  --dport 60000:61000 -j ACCEPT
# }}}

# allow incoming packets from related or established existing trusted
# connections so that we can connect to the Internet from this gateway
iptables -A INPUT -i eth0 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

apt-offline how to

update and upgrade

apt-offline set apt-offline.sig
apt-offline get apt-offline.sig -d [directory] --threads 5

apt-offline install [directory]
apt-get upgrade

install package

apt-offline set debian-install.sig --install-packages mc hdparm
apt-offline get debian-install.sig -d [directory] --threads 5

apt-offline install [directory]
apt-get install mc hdparm

misc

apt-key exportall | gpg --no-default-keyring --import --keyring /etc/apt/trusted.gpg

http://www.debian-administration.org/article/648/Offline_Package_Management_for_APT

http://blog.sleeplessbeastie.eu/2014/01/30/how-to-manage-packages-on-an-off-line-debian-system/

What are dvd1, dvd2, ... and update 1, update 2 in debian iso file list?

https://www.debian.org/CD/faq/#what-is