feat(ssh): set SSH_CLIENT environment variable for remote sessions

Add support for populating the SSH_CLIENT environment variable on
incoming SSH connections. This allows shells and scripts running on the
server to detect the client IP, source port, and server port for the
session, improving compatibility with remote shell behaviors (e.g., Bash
reading ~/.bashrc for non-interactive sessions).

This change aligns with standard SSH behavior and helps scripts and
monitoring tools identify remote clients reliably.

Author: henrybarreto

agent/server/modes/host/command/command_docker.go

@@ -16,13 +16,22 @@ func NewCmd(u *osauth.User, shell, term, host string, envs []string, command ...
 	nscommand, _ := nsenterCommandWrapper(u.UID, u.GID, u.HomeDir, command...)
 
 	cmd := exec.Command(nscommand[0], nscommand[1:]...) //nolint:gosec
+	// TODO: There are other environment variables we could set like SSH_CONNECTION, SSH_TTY, SSH_ORIGINAL_COMMAND, etc.
+	// We need to check which ones are relevant and set them accordingly.
+	// https://en.wikibooks.org/wiki/OpenSSH/Client_Applications
 	cmd.Env = []string{
 		"TERM=" + term,
 		"HOME=" + u.HomeDir,
 		"SHELL=" + shell,
 		"USER=" + u.Username,
 		"LOGNAME=" + u.Username,
 		"SHELLHUB_HOST=" + host,
+		// NOTE: We need to set the SSH_CLIENT because some applications (like bash) check for it to enable some
+		// features or load some files (like .bashrc). Currently, we don't have this information, so we set a fake one.
+		// TODO: Set the real SSH_CLIENT value.
+		// Format: "<ip> <source-port> <destination-port>"
+		// https://en.wikibooks.org/wiki/OpenSSH/Client_Applications
+		"SSH_CLIENT=127.0.0.1 0 0",
 	}
 	cmd.Env = append(cmd.Env, envs...)
 

agent/server/modes/host/command/command_native.go

@@ -29,11 +29,20 @@ func NewCmd(u *osauth.User, shell, term, host string, envs []string, command ...
 	}
 
 	cmd := exec.Command(command[0], command[1:]...) //nolint:gosec
+	// TODO: There are other environment variables we could set like SSH_CONNECTION, SSH_TTY, SSH_ORIGINAL_COMMAND, etc.
+	// We need to check which ones are relevant and set them accordingly.
+	// https://en.wikibooks.org/wiki/OpenSSH/Client_Applications
 	cmd.Env = []string{
 		"TERM=" + term,
 		"HOME=" + u.HomeDir,
 		"SHELL=" + shell,
 		"SHELLHUB_HOST=" + host,
+		// NOTE: We need to set the SSH_CLIENT because some applications (like bash) check for it to enable some
+		// features or load some files (like .bashrc). Currently, we don't have this information, so we set a fake one.
+		// TODO: Set the real SSH_CLIENT value.
+		// Format: "<ip> <source-port> <destination-port>"
+		// https://en.wikibooks.org/wiki/OpenSSH/Client_Applications
+		"SSH_CLIENT=127.0.0.1 0 0",
 	}
 	cmd.Env = append(cmd.Env, envs...)