--- -- Utility functions for libssh2. -- -- Provides helper class for the libssh2 binding that abstracts away -- details of running remote commands. -- -- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html -- @class module -- @name libssh2-utility local stdnse = require "stdnse" local table = require "table" local libssh2 = stdnse.silent_require "libssh2" SSHConnection = {} --- -- Returns a new connection object. -- -- @return A connection object. function SSHConnection:new () local o = {} setmetatable(o, self) self.__index = self return o end --- -- Sets up a connection with a server. -- -- @param host A host to connect to. -- @param port A port to connect to. -- @return true on success or nil on failure function SSHConnection:connect (host, port) self.session = libssh2.session_open(host, port.number) if self.session then return true end end --- -- Sets up a connection with a server. Call performed with pcall. -- -- @param host A host to connect to. -- @param port A port to connect to. -- @return true on success or error message on failure -- @return error code if error was triggered function SSHConnection:connect_pcall (host, port) local status, err status, self.session, err = pcall(libssh2.session_open, host, port.number) return status, err end --- -- Runs a shell command on the remote host. -- -- @param cmd A command to run. -- @return The command output. function SSHConnection:run_remote (cmd) if not (self.session and self.authenticated) then return false end local channel = libssh2.open_channel(self.session) libssh2.channel_exec(self.session, channel, cmd) libssh2.channel_send_eof(self.session, channel) local buff = {} local data = "" while not libssh2.channel_eof(channel) do data = libssh2.channel_read(self.session, channel) if data then table.insert(buff, data) end end return table.concat(buff) end --- -- Attempts to authenticate using provided credentials. -- -- @param username A username to authenticate as. -- @param password A password to authenticate as. -- @return true on success or false on failure. function SSHConnection:password_auth (username, password) if not self.session then return false end if libssh2.userauth_password(self.session, username, password) then self.authenticated = true return true else return false end end --- -- Attempts to authenticate using provided private key. -- -- @param username A username to authenticate as. -- @param privatekey_file A path to a privatekey. -- @param passphrase A passphrase for the privatekey. -- @return true on success or false on failure. function SSHConnection:publickey_auth (username, privatekey_file, passphrase) if not self.session then return false end if libssh2.userauth_publickey(self.session, username, privatekey_file, passphrase or "") then self.authenticated = true return true else return false end end --- -- Closes connection. function SSHConnection:disconnect () if self.session then libssh2.session_close(self.session) end end --- -- Sends ssh timeout -- -- @param ssh_timeout Time in miliseconds before considering the situation an error. function SSHConnection:set_timeout (ssh_timeout) if self.session then libssh2.set_timeout(self.session, ssh_timeout) end end --- -- Attempt to retrieve a list of supported authentication methods -- -- @param username A username to authenticate as. -- @return A list with the authentication methods on success or false on failure. function SSHConnection:list (username) if not self.session then return false end local status, methods = pcall(libssh2.userauth_list, self.session, username) if status then return methods end return false end --- -- Attempts to read public key file -- -- @param publickey An SSH public key file. -- @return true on success or false on error. -- @return public key data on success or error code on error. function SSHConnection:read_publickey (publickey) local status, result = pcall(libssh2.read_publickey, publickey) return status, result end --- -- Attempts authentication with public key -- -- @param username A username to authenticate as. -- @param key Base64 decrypted public key. -- @return true if the public key can be used to authenticate as the user, false otherwise -- @return Error message if an error occurs. function SSHConnection:publickey_canauth (username, key) local status, err if self.session then status, err = pcall(libssh2.publickey_canauth, self.session, username, key) if status then -- no error thrown; return the actual result status = err err = nil end else status = false err = "No session established" end return status, err end return _ENV