Windows 7: Disable port 445 for Samba tunneling edit 으로 이동

OpenVPN: certificate is not yet valid edit

When OpenVPN authentication process fails during a connection attempt with an error message like 'certificate is not yet vaild', check the date of your machine. According to a web source, it is required to have synchronized time between VPN server and client.

Correct time OpenVPN requires client and server to have more or less synchronized time. Therefore make sure that router has correct time. To check it use command date and if you get info about year 1970, you should enable NTP client. Also, ntp server has to be outside of your VPN as time should be corrected before VPN is established. If you have syslog enabled (to local server, or the server outside your VPN), errors like TLS Error: Unroutable control packet received from server_ip:1194 may indicate this problem. (This error message may appear if your certificates are not valid or have expired, too.) If you get an error message saying that your certificate is not yet valid, set the dd-wrt clock to UTC time (in the first configuration page).

To synchronize time, you can use ntpdate tool:

# ntpdate



Linux Mint: Can't change my laptop's screen brightness! edit

Edit /etc/default/grub and add acpi_osi, acpi_backlight options.

GRUB_CMDLINE_LINUX_DEFAULT="i915.modeset=1 acpi_osi= acpi_backlight=vendor"

Also checkout the kernel parameters under /sys/class/backlight/


문서를 돈주고 출력했는데 깜빡하고 프린터기를 안켰다? edit

등본과 같은 공적 문서나 학적기록 등을 결제하고 출력하였으나 정작 프린터는 꺼져있을때, 돈은 먹었고 프린트는 안되고 어찌한담?

이럴때는 프린터처럼 생긴 트레이 아이콘을 누르면 출력하고자 했던 문서가 출력 대기중인 문서로 남아있다. 이 문서의 임시파일을 찾아서 PDF와 같은 포멧으로 변환시켜주면 된다.

문서의 임시 파일의 위치는 다음과 같다:


탐색기로 열어서 대기중의 문서의 시간과 .SPL확장자로 끝나는 파일의 시간을 이용하여 문서를 찾고 해당 파일을 다른 폴더에 복사한 후 SPLViewer와 같은 프로그램으로 열어어서 PDF로 변환해주면 된다.


가상머신과 sshfs를 이용한 Samba 터널링 edit 으로 이동

리눅스 민트(우분투) 데스크톱 환경에서 한/영키를 누를때 Alt키가 같이 눌린다? edit

Linux Mint(Ubuntu): Hangul key is also Alt key?

아래 명령을 루트 유저로 실행:
Try this command as root user:

# xmodmap -e 'remove mod1 = Hangul'

자동 시작 스크립트 만들기; Make startup script


xmodmap -e 'remove mod1 = Hangul'
# chmod 755 /etc/init.d/
# update-rc.d -f defaults

노트: update-rc.d 시스템 명령은 최신버전의 우분투 환경에서 동작하지 않을 수 있습니다.
Note: update-rc.d may not working with latest version of Ubuntu.

Linux Mint: System is very slow! edit

It's caused by drm_kms_helper and I don't know what it is.

First, upgrade your system(apt-get update && apt-get upgrade && apt-get dist-upgrade) including kernel.

To disable it:

# echo N > /sys/module/drm_kms_helper/parameters/poll
# echo "options drm_kms_helper poll=N">/etc/modprobe.d/local.conf

To disable at start up, add below script to /etc/init.d/ and add using update-rc.d.


echo N> /sys/module/drm_kms_helper/parameters/poll
# update-rc.d -f defaults

After awhile, somehow the lags are gone away.


Linux Mint: Things to customize after initial install edit

  • Edit /etc/apt/sources.list to your local mirror - Add your country code(e.g KR for South Korea) to URLs
  • Upgrade system using apt-get update && apt-get upgrade && apt-get dist-upgrade
  • Install language support from system menu 'lanauge support' and install ibus to toggle between languages. - ibus and ibus-korean for korean users
  • If system is very slow, disable drm_kms_helper - see this post


iptables: Set rules to make firewall acts like a home routers. edit

Home routers accept connections established from inside and deny incoming connections that isn't

Initialize iptables rules:

# iptables -F
# iptables -X
# iptables -Z

Set default chain policies:

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

Accept on localhost:

# iptables -A INPUT -i lo -j ACCEPT
# iptables -A OUTPUT -o lo -j ACCEPT

Allow established sessions to receive traffic:

# iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

Save rules:

# iptables-save

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