data-encryption

How to Compile Kitty SSH Client from Source Code

Posted on by Waqar Azeem

I used Putty most of the time. Once I discovered Kitty, I haven’t looked back as it is same as Putty but on steroids. In the world of secure shell (SSH) clients, Kitty stands out as a feature-rich and highly customizable option. While precompiled versions are readily available for different operating systems, I wanted to see how Kitty is compiled.

In this blog post, I will walk you through the process of compiling Kitty SSH client from source code.

Prerequisites

Before diving into the compilation process, ensure that you have the necessary tools and libraries installed on your system. I will use Ubuntu Linux virtual machine and will use docker image which comes with all necessary packages required for compiling.

Update the Installation

It is always a good approach to install latest updates

sudo apt-get update
sudo apt-get upgrade

Output

Hit:1 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy InRelease
Get:2 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-updates InRelease [119 kB]
Get:3 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-backports InRelease [108 kB]
Hit:4 http://security.ubuntu.com/ubuntu jammy-security InRelease
Fetched 226 kB in 0s (523 kB/s)
Reading package lists… Done

Install Docker

We will use Docker to download image which has all the compiling tools required

sudo apt-get install docker.io -y

Output


Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following package was automatically installed and is no longer required:
  libnuma1
Use 'sudo apt autoremove' to remove it.
The following additional packages will be installed:
  bridge-utils containerd dns-root-data dnsmasq-base pigz runc ubuntu-fan
Suggested packages:
  ifupdown aufs-tools cgroupfs-mount | cgroup-lite debootstrap docker-doc rinse zfs-fuse
  | zfsutils
The following NEW packages will be installed:
  bridge-utils containerd dns-root-data dnsmasq-base docker.io pigz runc ubuntu-fan
0 upgraded, 8 newly installed, 0 to remove and 0 not upgraded.
Need to get 72.4 MB of archives.
After this operation, 287 MB of additional disk space will be used.
Get:1 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy/universe amd64 pigz amd64 2.6-1 [63.6 kB]
Get:2 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy/main amd64 bridge-utils amd64 1.7-1ubuntu3 [34.4 kB]
Get:3 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-updates/main amd64 runc amd64 1.1.4-0ubuntu1~22.04.3 [4244 kB]
Get:4 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-updates/main amd64 containerd amd64 1.6.12-0ubuntu1~22.04.1 [34.4 MB]
Get:5 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy/main amd64 dns-root-data all 2021011101 [5256 B]
Get:6 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-updates/main amd64 dnsmasq-base amd64 2.86-1.1ubuntu0.3 [354 kB]
Get:7 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy-updates/universe amd64 docker.io amd64 20.10.21-0ubuntu1~22.04.3 [33.3 MB]
Get:8 http://us-central1.gce.archive.ubuntu.com/ubuntu jammy/universe amd64 ubuntu-fan all 0.12.16 [35.2 kB]
Fetched 72.4 MB in 2s (42.1 MB/s)
Preconfiguring packages ...
Selecting previously unselected package pigz.
(Reading database ... 64995 files and directories currently installed.)
Preparing to unpack .../0-pigz_2.6-1_amd64.deb ...
Unpacking pigz (2.6-1) ...
Selecting previously unselected package bridge-utils.
Preparing to unpack .../1-bridge-utils_1.7-1ubuntu3_amd64.deb ...
Unpacking bridge-utils (1.7-1ubuntu3) ...
Selecting previously unselected package runc.
Preparing to unpack .../2-runc_1.1.4-0ubuntu1~22.04.3_amd64.deb ...
Unpacking runc (1.1.4-0ubuntu1~22.04.3) ...
Selecting previously unselected package containerd.
Preparing to unpack .../3-containerd_1.6.12-0ubuntu1~22.04.1_amd64.deb ...
Unpacking containerd (1.6.12-0ubuntu1~22.04.1) ...
Selecting previously unselected package dns-root-data.
Preparing to unpack .../4-dns-root-data_2021011101_all.deb ...
Unpacking dns-root-data (2021011101) ...
Selecting previously unselected package dnsmasq-base.
Preparing to unpack .../5-dnsmasq-base_2.86-1.1ubuntu0.3_amd64.deb ...
Unpacking dnsmasq-base (2.86-1.1ubuntu0.3) ...
Selecting previously unselected package docker.io.
Preparing to unpack .../6-docker.io_20.10.21-0ubuntu1~22.04.3_amd64.deb ...
Unpacking docker.io (20.10.21-0ubuntu1~22.04.3) ...
Selecting previously unselected package ubuntu-fan.
Preparing to unpack .../7-ubuntu-fan_0.12.16_all.deb ...
Unpacking ubuntu-fan (0.12.16) ...
Setting up dnsmasq-base (2.86-1.1ubuntu0.3) ...
Setting up runc (1.1.4-0ubuntu1~22.04.3) ...
Setting up dns-root-data (2021011101) ...
Setting up bridge-utils (1.7-1ubuntu3) ...
Setting up pigz (2.6-1) ...
Setting up containerd (1.6.12-0ubuntu1~22.04.1) ...
Created symlink /etc/systemd/system/multi-user.target.wants/containerd.service → /lib/systemd/system/containerd.service.
Setting up ubuntu-fan (0.12.16) ...
Created symlink /etc/systemd/system/multi-user.target.wants/ubuntu-fan.service → /lib/systemd/system/ubuntu-fan.service.
Setting up docker.io (20.10.21-0ubuntu1~22.04.3) ...
Adding group `docker' (GID 122) ...
Done.
Created symlink /etc/systemd/system/multi-user.target.wants/docker.service → /lib/systemd/system/docker.service.
Created symlink /etc/systemd/system/sockets.target.wants/docker.socket → /lib/systemd/system/docker.socket.
Processing triggers for dbus (1.12.20-2ubuntu4.1) ...
Processing triggers for man-db (2.10.2-1) ...
Scanning processes...                                                                      
Scanning linux images...                                                                   
Running kernel seems to be up-to-date.
No services need to be restarted.
No containers need to be restarted.
No user sessions are running outdated binaries.
No VM guests are running outdated hypervisor (qemu) binaries on this host.

Create Working Directory

We will create directory which will be mounted inside the container to save the compiled binaries

mkdir builds && ls -l

Output


total 4
drwxrwxr-x 2 wazeem wazeem 4096 Jul  1 12:36 builds

Download Docker Image

Download the docker image by cyd01 which has necessary components for compilation

sudo docker pull cyd01/cross-gcc

Output


Using default tag: latest
latest: Pulling from cyd01/cross-gcc
d99de3d304f0: Pull complete 
Digest: sha256:76e39c62686d0accda705b9f4b53bda43a08b15fbf1ceba54dc7620b347ed61a
Status: Downloaded newer image for cyd01/cross-gcc:latest
docker.io/cyd01/cross-gcc:latest

Run the Container

Now we will use a container from this image for code compilation. This command will drop us in container shell

sudo docker run --rm -it -v $(pwd)/builds:/builds cyd01/cross-gcc

Output


user@cross-gcc:/sources$

Download Source Code

Pull the source code from Github repository

git clone https://github.com/cyd01/KiTTY.git

Output


Cloning into 'KiTTY'...
remote: Enumerating objects: 4049, done.
remote: Counting objects: 100% (914/914), done.
remote: Compressing objects: 100% (281/281), done.
remote: Total 4049 (delta 641), reused 823 (delta 611), pack-reused 3135
Receiving objects: 100% (4049/4049), 10.02 MiB | 23.91 MiB/s, done.
Resolving deltas: 100% (2573/2573), done.

Modify the Code

Now we can make changes to code before compilation. For this demo, I will change the ssh client version. Using sed or vi, I am going to change ssh client version from “PuTTY-KiTTY” to “libssh_0.7.4“. Also make sure there is not spaces in the version name after “\0”

vi KiTTY/0.76b_My_PuTTY/utils/version.c

Save the changes and verify

cat KiTTY/0.76b_My_PuTTY/version.c |grep libssh

Output


const char sshver[] = "libssh_0.7.4\0" ;

Compile the Code

Now, we will compile the windows binaries

cd KiTTY/0.76b_My_PuTTY/windows
make -f MAKEFILE.MINGW cross

Output


sed -i 's#^typedef enum _WTS_VIRTUAL_CLASS #// typedef enum _WTS_VIRTUAL_CLASS #' window.c
sed -i 's/0/999/' version_major.txt
make -e TOOLPATH=/usr/bin/i686-w64-mingw32- -f MAKEFILE.MINGW putty.exe plink.exe pscp.exe psftp.exe pageant.exe puttygen.exe
make[1]: Entering directory '/sources/KiTTY/0.76b_My_PuTTY/windows'
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../ssh/agentf.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../aqsync.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../be_all_s.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../be_misc.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../callback.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../cmdline.c -DMASTER_PASSWORD=`cat ../../masterpassword.txt`
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../utils/conf.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../config.c
In file included from ../puttyps.h:10,
                 from ../putty.h:8,
                 from ../config.c:9:
../windows/platform.h:115:17: warning: '_stricmp' redeclared without dllimport attribute after being referenced with dll linkage
  115 | #define stricmp _stricmp
      |                 ^~~~~~~~
../windows/platform.h:115:17: note: in definition of macro 'stricmp'
  115 | #define stricmp _stricmp
      |                 ^~~~~~~~
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../proxy/cproxy.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../dialog.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../crypto/ecc-arithmetic.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../errsock.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../ldisc.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../logging.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SAVEDUMP -DMOD_DISABLEALTGR -DMOD_KEYMAPPING -DMOD_PUTTYX -DMOD_PORTKNOCKING -DMOD_HYPERLINK -DMOD_PRINTCLIP -DMOD_LAUNCHER -DMOD_RECONNECT -DMOD_RUTTY -DMOD_TUTTY -DMOD_ADB -DMOD_BACKGROUNDIMAGE -DMOD_ZMODEM -DMOD_PROXY -DMOD_FAR2L -I.././ -I../../ -I../charset/ -I../windows/ -I../unix/ -I../mac/ -I../macosx -I../../base64 -I../../bcrypt -I../../md5 -I../../regex -I../../url -I../../rutty                  -c ../ssh/mainchan.c
/usr/bin/i686-w64-mingw32-gcc  -Wall -O2 -std=gnu99 -Wvla -D_WINDOWS -DWIN32S_COMPAT -D_NO_OLDNAMES -D__USE_MINGW_ANSI_STDIO=1 -I.././ -I../charset/ -I../windows/ -I../unix/ -I../crypto/ -I../proxy/ -I../ssh/ -I../terminal/ -I../utils/ -D_WIN32_IE=0x0500 -DWINVER=0x0501 -D_WIN32_WINDOWS=0x0410 -D_WIN32_WINNT=0x0501 -DNO_SECUREZEROMEMORY -DCOVERITY -DNO_HTMLHELP -DFLJ1 -DMOD_WTS -DMOD_PERSO -DMOD_STARTBUTTON -DMOD_SA
.
.
.(truncated)
.
.
        void.o fromucs.o slookup.o sbcsdat.o sbcs.o utf8.o \
        ../../base64/base64.a ../../bcrypt/bcrypt.a ../../blocnote/notepad.a ../../jpeg/libjpeg.a \
        ../../md5/MD5check.a ../../mini/mini.a ../../regex/libregex.a \
        -ladvapi32 -lcomdlg32 -lgdi32 -limm32 -lpsapi -lole32 -lshell32 \
        -luser32 -lwsock32  -lwtsapi32
# -lcomctl32 -lwinmm -lwinspool -lole32 -lcrypt32
make[1]: Leaving directory '/sources/KiTTY/0.76b_My_PuTTY/windows'
cp putty.exe putty_nocompress.exe
upx --best --compress-icons=2 --compress-exports=0 putty.exe putty_portable.exe
                       Ultimate Packer for eXecutables
                          Copyright (C) 1996 - 2018
UPX 3.95        Markus Oberhumer, Laszlo Molnar & John Reiser   Aug 26th 2018

        File size         Ratio      Format      Name
   --------------------   ------   -----------   -----------
   2028032 ->    800256   39.46%    win32/pe     putty.exe                     
   2028032 ->    800256   39.46%    win32/pe     putty_portable.exe            
   --------------------   ------   -----------   -----------
   4056064 ->   1600512   39.46%                 [ 2 files ]

Packed 2 files.
mv putty.exe /builds/kitty.exe
mv putty_portable.exe /builds/kitty_portable.exe
mv putty_nocompress.exe /builds/kitty_nocompress.exe
mv plink.exe /builds/klink.exe
mv pscp.exe /builds/kscp.exe
mv psftp.exe /builds/ksftp.exe
mv pageant.exe /builds/kageant.exe
mv puttygen.exe /builds/kittygen.exe
rm *.o

Gather the binary file

At the completion of compilation, we will have binary files in our build directory

exit
ls -l

Output


total 6992
-rwxr-xr-x 1 wazeem wazeem  450560 Jul  1 13:43 kageant.exe
-rwxr-xr-x 1 wazeem wazeem  800256 Jul  1 13:42 kitty.exe
-rwxr-xr-x 1 wazeem wazeem 2028032 Jul  1 13:43 kitty_nocompress.exe
-rwxr-xr-x 1 wazeem wazeem  800256 Jul  1 13:43 kitty_portable.exe
-rwxr-xr-x 1 wazeem wazeem  539648 Jul  1 13:43 kittygen.exe
-rwxr-xr-x 1 wazeem wazeem  843776 Jul  1 13:43 klink.exe
-rwxr-xr-x 1 wazeem wazeem  839168 Jul  1 13:43 kscp.exe
-rwxr-xr-x 1 wazeem wazeem  845824 Jul  1 13:43 ksftp.exe

Verify the Changes

In the end, we will connect to ssh server using our compiled client and original client from vendor site to verify the modification using tcpdump/wireshark.

Tcpdump Output from Original Client

Tcpdump Output from Compiled Client

Download the Compiled Version

Here is the link to compiled version if you want to use. I highly recommend to use the official versions.

Download Kitty

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