Tag Archives: windows

UTF encoding

Code point range UTF-8 UTF-16
hexadecimal binary Bytes
(code bits)
binary hexadecimal Bytes
(code bits)
binary hexadecimal
00 00 00
00 00 7F
0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0111 1111
0xxx xxxx 00
xxxx xxxx xxxx xxxx 00 00
00 00 80
00 07 FF
0000 0000 0000 0000 1000 0000
0000 0000 0000 0111 1111 1111
110x xxxx
10xx xxxx
C2 80
00 08 00
00 FF FF
0000 0000 0000 1000 0000 0000
0000 0000 1111 1111 1111 1111
1110 xxxx
10xx xxxx
10xx xxxx
E0 A0 80
01 00 00
10 FF FF
0000 0001 0000 0000 0000 0000
0001 0000 1111 1111 1111 1111
1111 0xxx
10xx xxxx
10xx xxxx
10xx xxxx
F0 90 80 80
1101 10xx xxxx xxxx
1101 11xx xxxx xxxx
D8 00 DC 00

Test Jumbo Frames / MTU 9000


ping -M do -s 8972 xxx.xxx.xxx.xxx


ping -D -s 8184 xxx.xxx.xxx.xxx


ping -f -l 9000 xxx.xxx.xxx.xxx

Example results on Linux

If you’ve forgotten to enable jumbo frames/9k MTU on your client device you’re sending the ping from:

PING xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx): 8184 data bytes
ping: sendto: Message too long

If you have enabled jumbo frames on your client but not the destination (or a switch in between):

PING xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx): 8184 data bytes
Request timeout for icmp_seq 0

If you’ve done everything righ:

PING xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx): 8184 data bytes
8192 bytes from xxx.xxx.xxx.xxx: icmp_seq=0 ttl=128 time=0.714 ms

How to insert hotfixes and drivers and then create a bootable Windows Setup DVD

  • Create local folders c:\temp\src, c:\temp\mount, c:\temp\winremount, c:\temp\hotfix, and c:\temp\drivers.
  • Copy the setup sources from the DVD or a mounted ISO to C:\temp\src.
  • Copy the hotfix (.msu or .cab files) to C:\temp\hotfix.
  • Copy the driver files to c:\temp\drivers.
  • Run Command Prompt as an administrative.
dism /Mount-Wim /WimFile:c:\temp\src\sources\boot.wim /Index:1 /MountDir:c:\temp\mount
dism /Image:C:\temp\mount /Add-Package /PackagePath:c:\temp\hotfix
dism /Image:C:\temp\mount /Add-Driver /Driver:c:\temp\drivers /Recurse
dism /Unmount-Wim /MountDir:C:\temp\mount /Commit
dism /Mount-Wim /WimFile:c:\temp\src\sources\boot.wim /Index:2 /MountDir:c:\temp\mount
dism /Image:C:\temp\mount /Add-Package /PackagePath:c:\temp\hotfix
dism /Image:C:\temp\mount /Add-Driver /Driver:c:\temp\drivers /Recurse
  • Manually sort the folder C:\temp\mount\sources by date, and then copy the updated files to c:\temp\src\sources.
dism /Unmount-Wim /MountDir:C:\temp\mount /commit
  • Obtain the index from the Install.wim information by running the following command, and then check every index to see how many indexes have to be updated.
dism /Get-WimInfo /WimFile:c:\temp\src\sources\install.wim
  • Insert the hotfixes and drivers to install.wim and winre.wim by running the following commands:
dism /Mount-Wim /WimFile:c:\temp\src\sources\install.wim /Index:1 /MountDir:c:\temp\mount
dism /Image:C:\temp\mount /Add-Package /PackagePath:c:\temp\hotfix
dism /Image:C:\temp\mount /Add-Driver /Driver:c:\temp\drivers /Recurse
dism /Mount-Wim /WimFile:c:\temp\mount\windows\system32\recovery\winre.wim /Index:1 /MountDir:c:\temp\winremount
dism /Image:C:\temp\mount /Add-Package /PackagePath:c:\temp\hotfix
dism /Image:C:\temp\mount /Add-Driver /Driver:c:\temp\drivers /Recurse
dism /Unmount-Wim /MountDir:C:\temp\winremount /Commit
dism /Unmount-Wim /MountDir:C:\temp\mount /Commit

Note If there are multiple indexes in step 8, update them one by one.

Create an ISO file by running the following oscdimg commands.

Install the latest Windows ADK for Windows 8.1 update.

  • For Legacy BIOS Boot mode:
oscdimg -LTEST -m -u2 -bC:\temp\src\boot\etfsboot.com C:\temp\src C:\temp\Win7.ISO
  • For Legacy and UEFI BIOS multiple Boot mode:
oscdimg -LTEST -m -u2 -bootdata:2#p0,e,bC:\temp\src\boot\etfsboot.com#pEF,e,bC:\temp\src\efi\microsoft\boot\efisys.bin C:\temp\src C:\temp\Win7.ISO




A calculator supporting addition, substraction, multiplication and division (respectively : ADD, SUB ,MUL, and DIV operations). More information here.

dig 2.8.add.calc.postel.org @dns.postel.org +short
dig 8.2.sub.calc.postel.org @dns.postel.org +short
dig 2.8.mul.calc.postel.org @dns.postel.org +short
dig 8.2.div.calc.postel.org @dns.postel.org +short

IP to ASN Mapping

A service providing a way to map IPv4 and IPv6 addresses or prefixs to ASNs, get information about ASNs, and even find possible peers. More details here.

Mapping an IP address or prefix to a corresponding BGP Origin ASN:

dig TXT +short
"15169 | | US | arin |"
dig 4.8.8.origin.asn.cymru.com TXT +short
"15169 | | US | arin |"
dig TXT +short
"15169 | 2001:4860::/32 | US | arin | 2005-03-14"

Getting information about a given ASN:

dig AS15169.asn.cymru.com TXT +short
"15169 | US | arin | 2000-03-30 | GOOGLE - Google Inc.,US"


dig any google-public-dns-a.google.com +noall +answer
; <<>> DiG 9.8.3-P1 <<>> any google-public-dns-a.google.com +noall +answer
;; global options: +cmd
google-public-dns-a.google.com.	38271 IN TXT	"http://xkcd.com/1361/"
google-public-dns-a.google.com.	38271 IN AAAA	2001:4860:4860::8888
google-public-dns-a.google.com.	38271 IN A

more stuff at http://www.cambus.net/interesting-dns-hacks/

Get public IP using DNS

show public IP


dig o-o.myaddr.l.google.com txt @ns1.google.com +short
nslookup -type=txt o-o.myaddr.l.google.com ns1.google.com


dig myip.opendns.com @resolver1.opendns.com +short
nslookup myip.opendns.com resolver1.opendns.com


dig whoami.akamai.net. @ns1-1.akamaitech.net. +short
nslookup whoami.akamai.net. ns1-1.akamaitech.net.

other usage

dig o-o.myaddr.l.google.com txt
nslookup -type=txt o-o.myaddr.l.google.com

returns txt record of DNS request to authoritative source address
edns0-client-subnet if available, showing original DNS request source address

dig o-o.myaddr.l.google.com txt @ +short
nslookup -type=txt o-o.myaddr.l.google.com