feat: add support for ssh challenge type along with docs

_examples/simple-ssh/Dockerfile

@@ -0,0 +1,29 @@
+FROM ubuntu:16.04
+
+# Install SSH server and other required packages
+RUN apt-get update && apt-get install -y openssh-server sudo vim \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+# Configure SSH server
+RUN mkdir /var/run/sshd
+RUN echo 'PermitRootLogin yes' >> /etc/ssh/sshd_config
+RUN echo 'PasswordAuthentication yes' >> /etc/ssh/sshd_config
+
+# Create a CTF user with a default password
+RUN useradd -m -s /bin/bash ctf-user \
+    && echo "ctf-user:ctf-password" | chpasswd \
+    && echo "ctf-user ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/ctf-user
+
+# Add the challenge flag in a hidden location
+RUN echo "FLAG{SSH_CHALLENGE_FLAG}" > /home/ctf-user/.hidden_flag \
+    && chmod 600 /home/ctf-user/.hidden_flag
+
+# Add a welcome message
+RUN echo "Welcome to the SSH Challenge! Find the hidden flag." > /etc/motd
+
+# Expose SSH port
+EXPOSE 22
+
+# Start SSH service
+CMD ["/usr/sbin/sshd", "-D"]

_examples/simple-ssh/beast.toml

@@ -0,0 +1,19 @@
+[author]
+name = "ph03nix"
+email = "author@example.com"
+ssh_key = "ssh-ed25519 AAAAC3NzaC1lZD"
+
+[challenge.metadata]
+name = "simple-ssh"
+flag = "FLAG{SSH_CHALLENGE_FLAG}"
+type = "ssh"
+points = 150
+description = "SSH into the server and find the flag. Here are the creds: ctf-user:ctf-password"
+
+[[challenge.metadata.hints]]
+text = "Check for hidden files in the home directory"
+points = 10
+
+[challenge.env]
+docker_context = "Dockerfile"
+port_mappings = ["14442:22"]

core/config/challenge.go

@@ -230,9 +230,9 @@ func (config *ChallengeMetadata) ValidateRequiredFields() (error, bool) {
 // # Exists for flexibility reasons try to use existing base iamges wherever possible.
 // base_image = ""
 //
-// # Docker file name for specific type challenge - `docker`.
+// # Docker file name for specific type challenge - `docker` or `ssh`.
 // # Helps to build flexible images for specific user-custom challenges
-// docket_context = ""
+// docker_context = ""
 //
 // # Environment variables that can be used in the application code.
 // [[var]]
@@ -390,6 +390,23 @@ func (config *ChallengeEnv) ValidateRequiredFields(challType string, challdir st
 		return fmt.Errorf("max ports allowed for challenge : %d given : %d", core.MAX_PORT_PER_CHALL, len(config.Ports))
 	}
 
+	// For SSH challenges, ensure there's an explicit host->container mapping to SSH port.
+	// If user didn't specify a mapping like "host:22", map the first port in `Ports`
+	// to container SSH port so downstream code doesn't need the challenge type.
+	if challType == core.SSH_CHALLENGE_TYPE_NAME {
+		sshMapped := false
+		for _, pm := range config.PortMappings {
+			_, cp, err := utils.ParsePortMapping(pm)
+			if err == nil && cp == core.SSH_PORT {
+				sshMapped = true
+				break
+			}
+		}
+		if !sshMapped && len(config.Ports) > 0 {
+			config.PortMappings = append(config.PortMappings, fmt.Sprintf("%d:%d", config.Ports[0], core.SSH_PORT))
+		}
+	}
+
 	portMappings, err := config.GetPortMappings()
 	if err != nil {
 		return fmt.Errorf("error while parsing port mapping: %s", err)
@@ -495,6 +512,21 @@ func (config *ChallengeEnv) ValidateRequiredFields(challType string, challdir st
 				return fmt.Errorf("web Root directory does not exist")
 			}
 		}
+	} else if challType == core.SSH_CHALLENGE_TYPE_NAME {
+		// Challenge type is SSH which requires docker_context
+		if config.DockerCtx == "" {
+			return fmt.Errorf("docker_context can not be empty for SSH challenges")
+		} else if config.DockerCtx != "" {
+			if filepath.IsAbs(config.DockerCtx) {
+				return fmt.Errorf("docker_context path should be relative to challenge directory root")
+			} else if err := utils.ValidateFileExists(filepath.Join(challdir, config.DockerCtx)); err != nil {
+				return fmt.Errorf("docker_context file does not exist")
+			}
+		}
+
+		if !checkIfPortExistInMapping(portMappings, core.SSH_PORT) {
+			log.Warnf("No SSH port (22) found in port mappings for SSH challenge, it might not be accessible via SSH")
+		}
 	}
 
 	for _, script := range config.SetupScripts {

core/constants.go

@@ -64,6 +64,7 @@ const ( //chall types
 	SERVICE_CHALLENGE_TYPE_NAME string = "service"
 	WEB_CHALLENGE_TYPE_NAME     string = "web"
 	BARE_CHALLENGE_TYPE_NAME    string = "bare"
+	SSH_CHALLENGE_TYPE_NAME     string = "ssh"
 )
 
 const ( // chall actions
@@ -97,7 +98,7 @@ const ( // default config
 	ITERATIONS               int    = 65536
 	HASH_LENGTH              int    = 32
 	TIMEPERIOD               int64  = 6 * 60 * 60
-	SSH_PORT                 int    = 22
+	SSH_PORT                 uint32 = 22
 )
 
 const ( // roles
@@ -133,7 +134,7 @@ var USER_ROLES = map[string]string{
 }
 
 // Available challenge types
-var AVAILABLE_CHALLENGE_TYPES = []string{STATIC_CHALLENGE_TYPE_NAME, SERVICE_CHALLENGE_TYPE_NAME, BARE_CHALLENGE_TYPE_NAME, WEB_CHALLENGE_TYPE_NAME}
+var AVAILABLE_CHALLENGE_TYPES = []string{STATIC_CHALLENGE_TYPE_NAME, SERVICE_CHALLENGE_TYPE_NAME, BARE_CHALLENGE_TYPE_NAME, WEB_CHALLENGE_TYPE_NAME, SSH_CHALLENGE_TYPE_NAME}
 
 var DockerBaseImageForWebChall = map[string]map[string]map[string]string{
 	"php": {

docs/ChallTypes.md

@@ -4,7 +4,7 @@
 
 Any service whether it is a binary file, or a shell script, which needs to be instantiated on every connection can be easily hosted using `service` type challenge. **Xinetd** is for hosting these type of challenges inside a docker container.
 
-###Primary Requirements
+### Primary Requirements
 
 ```toml
 # Relative path to binary or script which needs to be executed when the specified
@@ -21,7 +21,7 @@ Web challenges are hosted using the corresponding images from Dockerhub. Current
 * Python : Django and Flask
 * Php
 
-###Primary Requirements
+### Primary Requirements
 
 ```toml
 # Relative directory corresponding to root of the challenge where the root
@@ -57,10 +57,24 @@ entrypoint = ""
 
 Authors might have tested the challenges in a isolated docker environment and might not want to port the challenge to one of these types. So they can use `docker` type challenge in which you can provide your own docker context file and ports.
 
-###Primary Requirements
+### Primary Requirements
 
 ```toml
 # Docker file name for specific type challenge - `docker`.
 # Helps to build flexible images for specific user-custom challenges
 docket_context = ""
 ```
+
+## SSH Challenge
+
+SSH challenges allow participants to connect directly to a container via SSH. This challenge type requires a dockerfile to be provided, which will be run with the necessary port mappings to allow SSH access. If the 22 port has been explicitly mapped to a host port using  `port_mappings` then it will be mapped that host port. Otherwise, if the `ports` list has been used, then the first port of that list, will be mapped to the container's 22 port. 
+
+### Primary Requirements
+
+```toml
+# Docker file name for the SSH challenge
+docker_context = ""
+
+# Port to be exposed for SSH access (typically 22)
+port_mappings = ["14442:22"]
+```

docs/SampleChallenges.md

@@ -184,3 +184,35 @@ The type of challenge consist of the following format - `web:php:<PHP Version>:<
 
 Make sure that you are installing all the mysql related dependencies in the `apt_deps` configuration parameter. As in the 
 above case `php*-mysql`
+
+## SSH Challenges
+
+SSH challenges allow participants to connect directly to a container using SSH and interact with a shell environment to solve the challenge. These challenges are ideal for scenarios where participants need to explore a system, find hidden files, or exploit vulnerabilities in a controlled environment.
+
+```toml
+[author]
+name = "ph03n1x"
+email = "author@example.com"
+ssh_key = "ssh-rsa AAAAB3NzaC1y..."
+
+[challenge.metadata]
+name = "simple-ssh"
+flag = "FLAG{SSH_CHALLENGE_FLAG}"
+type = "ssh"
+points = 150
+description = "SSH into the server and find the flag. The creds are ctf-user:ctf-password"
+
+[[challenge.metadata.hints]]
+text = "Check for hidden files in the home directory"
+points = 10
+
+[challenge.env]
+docker_context = "Dockerfile"
+port_mappings = ["14442:22"]  # Map external port 14442 to container's SSH port 22
+```
+
+Participants will be able to connect to this challenge using SSH:
+```
+ssh ctf-user@challenge-host -p 2222
+Password: ctf-password
+```