
More documentation might be found at https://github.com/FreeRDP/FreeRDP/wiki/Compilation

FreeRDP has a few dependencies that are required for proper operation:

1. SSL (required)

RDP requires a secure tunnel and utilizes TLS for this. We do not implement this
ourselves but reuse existing libraries:

We support

* OpenSSL our main development SSL library (-DWITH_OPENSSL=ON, default)
* LibreSSL (supported by community, -DWITH_OPENSSL=ON, drop in replacement)
* MBedTLS (supported by community, -DWITH_OPENSSL=OFF -DWITH_MBEDTLS=ON)

optionally there are some algorithms that can be shipped with FreeRDP itself if the SSL library deprecated them:
* -DWITH_INTERNAL_MD4=ON
* -DWITH_INTERNAL_MD5=ON
* -DWITH_INTERNAL_RC4=ON

2. Kerberos (optional, disable with -DWITH_KRB5=OFF)

Authentication to many services requires kerberos (especially if smartcards are in use)

We support:

* MIT
* Heimdal

3. JSON (optional, disable with -DWITH_JSON_DISABLED=ON)

Azure logon requires HTTP/JSON messages to be parsed.

We support:

* cJSON
* json-c

4. H264

RDP GFX modes (anything newer Windows 8.1 / Server 2012) supports a graphics mode based
on the H264 codec

We support

* OpenH264 (enable with -DWITH_OPENH264=ON)
* FFMPEG (x264 or OpenH264, enable with -DWITH_FFMPEG=ON)

There are some platform specific implementations too (e.g. mediacodec on android) but these
two are the options that are always required.

5. Graphics scaling support (optional, required for HighDPI support)

High DPI support and smart-sizing option require bitmaps to be scaled by the client. 

We support

* Swscale (enable with -DWITH_SWSCALE=ON)
* Cairo (enable with -DWITH_CAIRO=ON)

6. Audio encoders/decoders (optional, hightly recommended though)

Sound and Microphone options allow transmission of data in compressed formats.
The most widely supported formats are uncompressed PCM (all systems support that)
and compressed AAC (windows 8 or newer). Some other codecs are supported as well (GSM)
but do not provide the same quality as the afore mentioned ones.

We support

* FAAC / FAAD2 / soxr (encoder/decoder/resampling)
* GSM (older low bandwidth codec, -DWITH_GSM=ON)
* FFMPEG (-DWITH_DSP_FFMPEG)
* SOXR (optional, resampling library, enable with -DWITH_SOX!=ON)

to enable some experimental codecs (mainly AAC encoding) add -DWITH_DSP_EXPERIMENTAL=ON

7. Smartcard (optional)

To utilize smartcards for authentication/redirection 

We support

* PCSC (disable with -DWITH_PCSC=OFF)
* pkcs11 (disable with -DWITH_PKCS11=OFF)

PCSC is required for smartcard redirection, pkcs11 for NLA smartcard logon support

8. Unicode (required, use -DWITH_UNICODE_BUILTIN=ON to utilize custom char16 <--> utf8 conversion routines)

Most of the protocol preferably uses UCS-2/UTF16 for strings. To convert to/from UTF-8 a
unicode support library is required:

* Windows natively supports these (well, it is a microsoft protocol after all ;))
* ICU on linux/unix and android
* On Apple (iOS/Mac) we use native NSString unicode conversion routines

9. USB redirection (optional, disable with -DCHANNEL_URBDRC=OFF)

The protocol has an extension (channel) to allow low level USB redirection

We support

* libusb 1

10. Platform support (mainly linux, for others the platform SDK is usually enough)

* SDL2 for the SDL client (all platforms, disable with -DWITH_CLIENT_SDL=OFF)
* CUPS (linux/apple) for printing support (disable with -DWITH_CUPS=OFF)
* libsystemd (linux) for journald logging support (disable with -DWITH_LIBSYSTEMD=OFF)
* PAM headers/libraries (server side authentication)
* FUSE for file clipboard support (linux/mac os, disable with -DWITH_FUSE=OFF) 
* Wayland for wlfreerdp (disable with -DWITH_WAYLAND=OFF)
* X11 development headers for X11 client (disable with -DWITH_X11=OFF)
* ALSA development headers/libraries (disable with -DWITH_ALSA=OFF)
* PULSE development headers/libraries (disable with -DWITH_PULSE=OFF)
* OSS development headers/libraries (disable with -DWITH_OSS=OFF)

11. WebAuthn / FIDO2 redirection (optional, disable with -DCHANNEL_RDPEWA=OFF)

The [MS-RDPEWA] WebAuthn Virtual Channel Extension allows forwarding WebAuthn/FIDO2
authenticator requests from the RDP server to the client's local security keys.
This enables passwordless authentication (e.g. passkeys) and two-factor authentication
inside the remote session using hardware security keys plugged into the client machine.

Enabled automatically when the required libraries are found. Requires:

* libcbor (CBOR encoding/decoding)
* libfido2 (FIDO2/CTAP2 authenticator communication)

On Debian/Ubuntu: apt install libcbor-dev libfido2-dev
On Fedora: dnf install libcbor-devel libfido2-devel

The channel is activated via the "redirectwebauthn" .rdp file setting
(FreeRDP_RedirectWebAuthN).

12. Server support

FreeRDP does provide server side RDP protocol implementation as well.
These are used by the RDP proxy (disable with -DWITH_PROXY=OFF) as well as shadow server (disable with -DWITH_SHADOW=OFF)

there are some (incomplete) platform implementations (enable with -DWITH_PLATFORM_SERVER=ON) which compile but do not provide anything useful yet.

13. Samples

There are a client and server sample provided. (disable with -DWITH_SAMPLE=OFF)

14. Tools (optional)

a couple of helper utilities are build alongside the client and server executables and libraries. These are mostly for handling certificates and NTLM hashes.
disable with -DWITH_WINPR_TOOLS=OFF

15. Building recommendations

* Use Ninja to speed up your builds
* For release builds add -DCMAKE_BUILD_TYPE=Release (or RelWithDebInfo for less optimized but with debug symbols)
* -DWITH_VERBOSE_WINPR_ASSERT=OFF reduces the size of the build considerably but removes lots
  of sanity checks in code. Recommended for stable builds, for builds not from stable releases
  it is recommended to keep -DWITH_VERBOSE_WINPR_ASSERT=ON to have useful information on crashes.

16. Example build instructions:

Assume we have the source checked out to /tmp/freerdp/src and we want to install to /tmp/freerdp/install:
(on windows this needs to be called from a visual studio command prompt or a cmd that has run vcvarsall.bat, paths obviously need to be adjusted)

cmake -GNinja -DCMAKE_BUILD_TYPE=Release -DWITH_VERBOSE_WINPR_ASSERT=OFF -DCMAKE_PREFIX_PATH=/tmp/freerdp/install -B /tmp/freerdp/build -S /tmp/freerdp/src
cmake --build /tmp/freerdp/build --target install

17. Useful tips:

* there is ccmake (linux/mac os) that is a curses ui to show a current CMakeCache.txt build configuration. There it is easy to check/change variables
* CMake supports preload files (see ci/ subfolder in repo) that allows creating a (custom) build configuration that can then be applied with cmake -C<preload file>
