Posts Tagged ‘text ascii’

How to move transfer binary files encoded with base64 on Linux with Copy Paste of text ASCII encoded string

Monday, October 25th, 2021


If you have to work on servers in a protected environments that are accessed via multiple VPNs, Jump hosts or Web Citrix and you have no mean to copy binary files to your computer or from your computer because you have all kind of FTP / SFTP or whatever Data Copy clients disabled on remote jump host side or CITRIX server and you still are looking for a way to copy files between your PC and the Remote server Side.
Or for example if you have 2 or more servers that are in a special Demilitarized Network Zones ( DMZ ) and the machines does not have SFTP / FTP / WebServer or other kind of copy protocol service that can be used to copy files between the hosts and you still need to copy some files between the 2 or more machines in a slow but still functional way, then you might not know of one old school hackers trick you can employee to complete the copy of files between DMZ-ed Server Host A lets say with IP address ( -> Server Host B ( The way to complete the binary file copy is to Encode the binary on Server Host A and then, use cat  command to display the encoded string and copy whole encoded cat command output  to your (local PC buffer from where you access the remote side via SSH via the CITRIX or Jump host.). Then decode the encoded file with an encoding tool such as base64 or uuencode. In this article, I'll show how this is done with base64 and uuencode. Base64 binary is pretty standard in most Linux / Unix OS-es today on most Linux distributions it is part of the coreutils package.
The main use of base64 encoding to encode non-text Attachment files to Electronic Mail, but for our case it fits perfectly.
Keep in mind, that this hack to copy the binary from Machine A to Machine B of course depends on the Copy / Paste buffer being enabled both on remote Jump host or Citrix from where you reach the servers as well as your own PC laptop from where you access the remote side.


Base64 Encoding and Decoding text strings legend

The file copy process to the highly secured PCI host goes like this:

1. On Server Host A encode with md5sum command

[root@serverA ~]:# md5sum -b /tmp/inputbinfile-to-encode
66c4d7b03ed6df9df5305ae535e40b7d *inputbinfile-to-encode


As you see one good location to encode the file would be /tmp as this is a temporary home or you can use alternatively your HOME dir

but you have to be quite careful to not run out of space if you produce it anywhere 🙂


2. Encode the binary file with base64 encoding

 [root@serverB ~]:# base64 -w0 inputbinfile-to-encode > outputbin-file.base64

The -w0 option is given to disable line wrapping. Line wrapping is perhaps not needed if you will copy paste the data.


Base64 Encoded string chunk with line wrapping

For a complete list of possible accepted arguments check here.

3. Cat the inputbinfile-to-encode just generated to display the text encoded file in your SecureCRT / Putty / SuperPutty etc. remote ssh access client

[root@serverA ~]:# cat /tmp/inputbinfile-to-encode
EAAOAALAEAAHQAcAAYAAAAEAAA ……………………………………………………………… cTD6lC+ViQfUCPn9bs


4. Select the cat-ted string and copy it to your PC Copy / Paste buffer

If the bin file is not few kilobytes, but few megabytes copying the file might be tricky as the string produced from cat command would be really long, so make sure the SSH client you're using is configured to have a large buffer to scroll up enough and be able to select the whole encoded string until the end of the cat command and copy it to Copy / Paste buffer.


5. On Server Host B paste the bas64 encoded binary inside a newly created file

Open with a text editor vim / mc or whatever is available

[root@serverB ~]:# vi inputbinfile-to-encode

Some very paranoid Linux / UNIX systems might not have even a normal text editor like 'vi' if you happen to need to copy files on such one a useful thing is to use a simple cat on the remote side to open a new File Descriptor buffer, like this:

[root@server2 ~]:# cat >> inputbinfile-to-encode <<'EOF'
Paste the string here


6. Decode the encoded binary with base64 cmd again

[root@serverB ~]:# base64 –decode outputbin-file.base64 > inputbinfile-to-encode


7. Set proper file permissions (the same as on Host A)

[root@serverB ~]:#  chmod +x inputbinfile-to-encode


8. Check again the binary file checksum on Host B is identical as on Host A

[root@serverB ~]:# md5sum -b inputbinfile-to-encode
66c4d7b03ed6df9df5305ae535e40b7d *inputbinfile-to-encode

As you can md5sum match on both sides so file should be OK.


9. Encoding and decoding files with uuencode

If you are lucky and you have uuencode installed (sharutils) package is present on remote machine to encode lets say an archived set of binary files in .tar.gz format do:

Prepare the archive of all the files you want to copy with tar on Host A:

[root@Machine1 ~]:#  tar -czvf /bin/whatever /usr/local/bin/htop /usr/local/bin/samhain /etc/hosts archived-binaries-and-configs.tar.gz

[root@Machine1 ~]:# uuencode archived-binaries-and-configs.tar.gz archived-binaries-and-configs.uu

Cat / Copy / paste the encoded content as usual to a file on Host B:

Then on Machine 2 decode:

[root@Machine2 ~]:# uuencode -c < archived-binaries-and-configs.tar.gz.uu



In this short method I've shown you a hack that is used often by script kiddies to copy over files between pwn3d machines, a method which however is very precious and useful for sysadmins like me who has to admin a paranoid secured servers that are placed in a very hard to access environments.

With the same method you can encode or decode not only binary file but also any standard input/output file content. base64 encoding is quite useful stuff to use also in bash scripts or perl where you want to have the script copy file in a plain text format . Datas are encoded and decoded to make the data transmission and storing process easier. You have to keep in mind always that Encoding and Decoding are not similar to encryption and decryption as encr. deprytion gives a special security layers to the encoded that. Encoded data can be easily revealed by decoding, so if you need to copy between the servers very sensitive data like SSL certificates Private RSA / DSA key, this command line utility tool better to be not used for sesitive data copying.



Converting JPEG Images to ASCII Art text (picture) in Microsoft Windows (2000 / XP / Vista / 7)

Friday, May 18th, 2012

A friend of mine, just mentioned about a program ASCIIPic – capable of converting graphic images in JPEG to plain text ASCII in Microsoft Windows OSes.
Yesterday I blogged about caca-utils (img2txt) – console tool to convert picture graphics to plain text ASCII , so knowing of the Windows freeware ASCIIPic existence catched my attention and I decided to give it a try to get idea what is situation with Images to ASCII text convertion in Windows? 🙂.

1. Generating ASCII from JPEG images with ASCII Pic

As I don't have a Microsoft Windows OS at hand, I downloaded it and run it on my Debian notebook with WINE (Wine Is Not an Emulator) MS-Windows emulator.

For my surprise the program run succesfuly its GUI interface and worked pretty smooth even emulated on Linux.

ASCII Pic 2.0 JPG PNG GIF to ASCII text MS Windows Convertor screenshot

As of time of writting, the latest version of the freeware program available is 2.0. You see in above screenshot the program is pretty intutive to use. You select an Input file, an Output file and you're ready to Process the image to TXT.
One small note to make here is the program couldn't recognize as Input files images in PNG or GIF formats, it seems the only image formats the program recognizes as input are JPEG and BMP.

ASCII Pic Windows image to ASCII program picture shot

The converted images to ASCII results are quite unsatisfactory, I tried converting few pictures originally in size 1024×768 but the produced ASCII was messy huge (the program didn't automatically set height / width dimensions to 60×80 and therefore, when I revied the produced pictures, they were very ugly and hardly readable. It could be the same image looks better if reviewed in MS-Windows Notepad but I seriously doubt that …

I thought some improvement to the produced ASCII image might be possible from the app options so I played around with the Zoom, Negation, Brightness and Monochrome options, none of them had a drastic change on the output. Using any of the program options didn't make the output TXT "image" to look closer riginal JPEGs..

ASCII Pic 2.0 Windows picture to ASCII Program options screenshot

ASCII Pic official website contains a number of other tiny tools, like WinKill and RemoteShut, however most of the tools are already too obslete and useless just like ASCII Pic

If I have to compare ASCIIPic produced ASCII Images to libcaca's Linux img2txt, asciipic's ASCII images are a piece of crap.

2. jp2a command line tool image to ASCII generator

As of time of writting a good alternative program I found for Windows is jp2a
jp2a is a free GPL-ed software available for all major operating system architectures Linux, BSD, Mac OS X, Windows.
jp2a is a command line tool and lacks any GUI interface but if compared to ASCII Pic the output ASCII image is awesome.

jp2a Windows binary can be downloaded from here , also I've made a mirror of windows jp2a bin in case if it disappears here

3. ASCII Generator 2 (asc2gen) – Windows GUI Images to ASCII generator

ASC 2 Gen is actually the best I can find program to convert images to ascii in Win as of time of writting.
Just like img2txt it generates pretty decent looking text images.

ASC2Gen failed to run emulated on my Linux host with wine version 1.0.1, hence to test it I used a a Windows host via teamviewer.

Below are few screenshots illustrating most of the options ASCII2GEN provides:

asc2gen Microsoft Windows image to ascii generator inverted penguins screenshot

asc2gen penguins in inverted color set (black color text background)

ASC2Gen backhead penguins ascii picture screenshot

ASC2GEN flipped backhed generated image to ASCII

ascii2gen generate images to ascii in colors Microsoft Windows shot

Picture to ASCII text converted with ASCII colors

Dithering Windows image to ascii text generated picture ASCII

ascii2gen dithering level option shot

asc2gen jpeg, png, gif to plain text ascii brightness contrast screenshot pic

asc2gen contrast / brigthness atune shot

ascii2gen penguins converted images to plain text inverted with capital letters for picture

asc2gen save as options shot

Something else nice is it supports a lot of image file formats as input including (BMP and GIF) images.
I've also made a mirror of asc2gen v. 2.0.0 here

While researching online, I found plenty of other Image to ASCII geneartors, however as I didn't tested them I can't say if they are  better ones.
Anyways I will be happy to hear if anyone knows other good ASCII generator alternative progs for Winblows?