docs: add more thorough developer documentation

sparse-05/README.md

@@ -25,6 +25,12 @@ Sparse 0.5 is a stopgap solution until the C2 framework itself is more mature. I
 
 # Obtaining
 
+Sparse 0.5 is immediately ready to build from source if using the [Nix package manager](https://nixos.org/download) [with flakes enabled](https://nixos.wiki/wiki/Flakes) by running `nix build .#sparse-05-client`.
+
+## FreeBSD support
+
+Building normally will only produce a client that can generate beacons for Linux and Windows, lacking proper FreeBSD support. To build the client with FreeBSD support, create a FreeBSD build environment by running `vagrant up` and compiling a FreeBSD sparse binary by running `sparse-build` or `sparse-build --release`. With the FreeBSD binary built, copy it from `target/x86_64-unknown-freebsd` to `sparse-05/sparse-05-freebsd-server`, and rebuild using Nix
+
 Currently, there are no prebuilt binaries. However, sparse can easily be built if the [Nix package manager](https://nixos.org/download) is installed. Just clone this repository and run `nix build .#sparse-05-client` and the client will be placed in `result/bin`.
 
 # Use
@@ -33,12 +39,13 @@ Using sparse centers around the client. The client can generate new servers as w
 
 ## Generating a new server
 
-Sparse supports 3 different targets:
+Sparse supports 4 different targets:
 - Linux
 - Windows
 - Windows service
+- FreeBSD
 
-The basics center around `sparse-05-client generate <name> [-p <port>] [-t <target>]`. This generates both a server and the configuration file necessary to connect to the server. The keys and port ensure that the connection is unique, which has the added property that multiple versions of `sparse-05` can be running on a target system with the same port.
+The basics center around `sparse-05-client generate <name> [-p <port>] [-t <target>]`. This generates both a server and the configuration file necessary to connect to the server.
 
 If the port is not specified, it defaults to 54248.
 
@@ -62,6 +69,10 @@ The Windows service has the same requirements, but can be installed with `sc cre
 
 As of Jan 25 2023, Windows Defender marks the Windows service binary as malicious
 
+### FreeBSD
+
+Create a service to run the resulting binary as root
+
 ## Connect
 
 After installing and running the server, it is possible to connect using the generated `scon` file and `sparse-05-client` with `sparse-05-client connect <name>.scon <service ip>:<service port>`.
@@ -71,3 +82,9 @@ This brings up a shell that can run commands. However, there are special command
 - `#help`: shows sparse specific help
 - `#sysinfo`: prints information about the system being connected to
 - `#upload [local] [remote]`: uploads a file from the local path to the remote path
+- `#download [remote] [local]`: downloads a file from the remote path to the local path
+- `#edit [remote]`: downloads a file remotely and opens it in `$EDITOR`, and uploads the final version
+
+## Connection test
+
+To verify that an installed service is still alive and working, run `sparse-05-client connect-test <name>.scon <service ip>:<service port>`