#580 supervisor wired/wireless dual networking

scada-common/comms.lua

@@ -17,7 +17,7 @@ local max_distance = nil
 local comms = {}
 
 -- protocol/data versions (protocol/data independent changes tracked by util.lua version)
-comms.version = "3.0.8"
+comms.version = "3.0.9"
 comms.api_version = "0.0.10"
 
 ---@enum PROTOCOL
@@ -49,13 +49,14 @@ local MGMT_TYPE = {
     ESTABLISH = 0,       -- establish new connection
     KEEP_ALIVE = 1,      -- keep alive packet w/ RTT
     CLOSE = 2,           -- close a connection
-    RTU_ADVERT = 3,      -- RTU capability advertisement
+    PROBE = 3,
-    RTU_DEV_REMOUNT = 4, -- RTU multiblock possbily changed (formed, unformed) due to PPM remount
+    RTU_ADVERT = 4,      -- RTU capability advertisement
-    RTU_TONE_ALARM = 5,  -- instruct RTUs to play specified alarm tones
+    RTU_DEV_REMOUNT = 5, -- RTU multiblock possbily changed (formed, unformed) due to PPM remount
-    DIAG_TONE_GET = 6,   -- (API) diagnostic: get alarm tones
+    RTU_TONE_ALARM = 6,  -- instruct RTUs to play specified alarm tones
-    DIAG_TONE_SET = 7,   -- (API) diagnostic: set alarm tones
+    DIAG_TONE_GET = 7,   -- (API) diagnostic: get alarm tones
-    DIAG_ALARM_SET = 8,  -- (API) diagnostic: set alarm to simulate audio for
+    DIAG_TONE_SET = 8,   -- (API) diagnostic: set alarm tones
-    INFO_LIST_CMP = 9    -- (API) info: list all computers on the network
+    DIAG_ALARM_SET = 9,  -- (API) diagnostic: set alarm to simulate audio for
+    INFO_LIST_CMP = 10   -- (API) info: list all computers on the network
 }
 
 ---@enum CRDN_TYPE
@@ -89,6 +90,12 @@ local ESTABLISH_ACK = {
 ---@enum DEVICE_TYPE device types for establish messages
 local DEVICE_TYPE = { PLC = 0, RTU = 1, SVR = 2, CRD = 3, PKT = 4 }
 
+---@enum PROBE_ACK
+local PROBE_ACK = {
+    OPEN = 0,
+    CONFLICT = 1
+}
+
 ---@enum PLC_AUTO_ACK
 local PLC_AUTO_ACK = {
     FAIL = 0,            -- failed to set burn rate/burn rate invalid
@@ -130,6 +137,8 @@ comms.CRDN_TYPE = CRDN_TYPE
 comms.ESTABLISH_ACK = ESTABLISH_ACK
 comms.DEVICE_TYPE = DEVICE_TYPE
 
+comms.PROBE_ACK = PROBE_ACK
+
 comms.PLC_AUTO_ACK = PLC_AUTO_ACK
 
 comms.UNIT_COMMAND = UNIT_COMMAND

scada-common/network.lua

@@ -82,7 +82,9 @@ end
 function network.nic(modem)
     local self = {
         -- modem interface name
-        iface = ppm.get_iface(modem),
+        iface = "?",
+        -- phy name
+        name = "?",
         -- used to quickly return out of tx/rx functions if there is nothing to do
         connected = true,
         -- used to avoid costly MAC calculations if not required
@@ -94,6 +96,10 @@ function network.nic(modem)
     ---@class nic:Modem
     local public = {}
 
+    -- get the phy name
+    ---@nodiscard
+    function public.phy_name() return self.name end
+
     -- check if this NIC has a connected modem
     ---@nodiscard
     function public.is_connected() return self.connected end
@@ -102,11 +108,14 @@ function network.nic(modem)
     ---@param reconnected_modem Modem
     function public.connect(reconnected_modem)
         modem = reconnected_modem
+
+        self.iface     = ppm.get_iface(modem)
+        self.name      = util.c(util.trinary(modem.isWireless(), "WLAN_PHY", "ETH_PHY"), "{", self.iface, "}")
         self.connected = true
+        self.use_hash  = c_eng.hmac and modem.isWireless()
 
+        -- open only previously opened channels
         modem.closeAll()
-
-        -- open previously opened channels
         for _, channel in ipairs(self.channels) do
             modem.open(channel)
         end

supervisor/backplane.lua

@@ -18,7 +18,7 @@ local _bp = {
 
     wd_nic = nil,       ---@type nic|nil wired nic
     wl_nic = nil,       ---@type nic|nil wireless nic
-    nic_map = {}
+    nic_map = {}        ---@type nic[] connected nics
 }
 
 backplane.nics = _bp.nic_map

supervisor/supervisor.lua

@@ -13,6 +13,7 @@ local supervisor = {}
 local PROTOCOL      = comms.PROTOCOL
 local DEVICE_TYPE   = comms.DEVICE_TYPE
 local ESTABLISH_ACK = comms.ESTABLISH_ACK
+local PROBE_ACK     = comms.PROBE_ACK
 local MGMT_TYPE     = comms.MGMT_TYPE
 
 ---@type svr_config
@@ -156,14 +157,11 @@ function supervisor.comms(_version, fp_ok, facility)
     local function println(message) if not fp_ok then util.println_ts(message) end end
 
     local self = {
-        last_est_acks = {}
+        last_est_acks = {}  ---@type ESTABLISH_ACK[]
     }
 
     comms.set_trusted_range(config.TrustedRange)
 
-    -- configure network channels
-    pcie.nic.reset_open(config)
-
     -- pass system data and objects to svsessions
     svsessions.init(fp_ok, config, facility)
 
@@ -175,8 +173,7 @@ function supervisor.comms(_version, fp_ok, facility)
     ---@param ack ESTABLISH_ACK
     ---@param data? any optional data
     local function _send_establish(nic, packet, ack, data)
-        local s_pkt = comms.scada_packet()
+        local s_pkt, m_pkt = comms.scada_packet(), comms.mgmt_packet()
-        local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(MGMT_TYPE.ESTABLISH, { ack, data })
         s_pkt.make(packet.src_addr(), packet.seq_num() + 1, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
@@ -185,6 +182,188 @@ function supervisor.comms(_version, fp_ok, facility)
         self.last_est_acks[packet.src_addr()] = ack
     end
 
+    -- send a probe response
+    ---@param nic nic
+    ---@param packet scada_packet
+    ---@param ack PROBE_ACK
+    local function _send_probe(nic, packet, ack)
+        local s_pkt, m_pkt = comms.scada_packet(), comms.mgmt_packet()
+
+        m_pkt.make(MGMT_TYPE.PROBE, { ack })
+        s_pkt.make(packet.src_addr(), packet.seq_num() + 1, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+
+        nic.transmit(packet.remote_channel(), config.SVR_Channel, s_pkt)
+    end
+
+    --#region Establish Handlers
+
+    -- handle a PLC establish
+    ---@param nic nic
+    ---@param packet mgmt_frame
+    ---@param src_addr integer
+    ---@param i_seq_num integer
+    ---@param last_ack ESTABLISH_ACK
+    local function _establish_plc(nic, packet, src_addr, i_seq_num, last_ack)
+        local comms_v    = packet.data[1]
+        local firmware_v = packet.data[2]
+        local dev_type   = packet.data[3]
+
+        if comms_v ~= comms.version then
+            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                log.info(util.c("dropping PLC establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+            end
+
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+        elseif dev_type == DEVICE_TYPE.PLC then
+            -- PLC linking request
+            if packet.length == 4 and type(packet.data[4]) == "number" then
+                local reactor_id = packet.data[4]
+
+                -- check ID validity
+                if reactor_id < 1 or reactor_id > config.UnitCount then
+                    -- reactor index out of range
+                    if last_ack ~= ESTABLISH_ACK.DENY then
+                        log.warning(util.c("PLC_ESTABLISH: denied assignment ", reactor_id, " outside of configured unit count ", config.UnitCount))
+                    end
+
+                    _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+                else
+                    -- try to establish the session
+                    local plc_id = svsessions.establish_plc_session(nic, src_addr, i_seq_num, reactor_id, firmware_v)
+
+                    if plc_id == false then
+                        -- reactor already has a PLC assigned
+                        if last_ack ~= ESTABLISH_ACK.COLLISION then
+                            log.warning(util.c("PLC_ESTABLISH: assignment collision with reactor ", reactor_id))
+                        end
+
+                        _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.COLLISION)
+                    else
+                        -- got an ID; assigned to a reactor successfully
+                        println(util.c("PLC (", firmware_v, ") [@", src_addr, "] \xbb reactor ", reactor_id, " connected"))
+                        log.info(util.c("PLC_ESTABLISH: PLC (", firmware_v, ") [@", src_addr, "] reactor unit ", reactor_id, " PLC connected with session ID ", plc_id, " on ", nic.phy_name()))
+                        _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
+                    end
+                end
+            else
+                log.debug("PLC_ESTABLISH: packet length mismatch/bad parameter type")
+                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+            end
+        else
+            log.debug(util.c("illegal establish packet for device ", dev_type, " on PLC channel"))
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+        end
+    end
+
+    -- handle an RTU gateway establish
+    ---@param nic nic
+    ---@param packet mgmt_frame
+    ---@param src_addr integer
+    ---@param i_seq_num integer
+    ---@param last_ack ESTABLISH_ACK
+    local function _establish_rtu_gw(nic, packet, src_addr, i_seq_num, last_ack)
+        local comms_v    = packet.data[1]
+        local firmware_v = packet.data[2]
+        local dev_type   = packet.data[3]
+
+        if comms_v ~= comms.version then
+            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                log.info(util.c("dropping RTU_GW establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+            end
+
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+        elseif dev_type == DEVICE_TYPE.RTU then
+            if packet.length == 4 then
+                -- this is an RTU advertisement for a new session
+                local rtu_advert = packet.data[4]
+                local s_id = svsessions.establish_rtu_session(nic, src_addr, i_seq_num, rtu_advert, firmware_v)
+
+                println(util.c("RTU (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                log.info(util.c("RTU_GW_ESTABLISH: RTU_GW (",firmware_v, ") [@", src_addr, "] connected with session ID ", s_id, " on ", nic.phy_name()))
+                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
+            else
+                log.debug("RTU_GW_ESTABLISH: packet length mismatch")
+                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+            end
+        else
+            log.debug(util.c("illegal establish packet for device ", dev_type, " on RTU channel"))
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+        end
+    end
+
+    -- handle a coordinator establish
+    ---@param nic nic
+    ---@param packet mgmt_frame
+    ---@param src_addr integer
+    ---@param i_seq_num integer
+    ---@param last_ack ESTABLISH_ACK
+    local function _establish_crd(nic, packet, src_addr, i_seq_num, last_ack)
+        local comms_v    = packet.data[1]
+        local firmware_v = packet.data[2]
+        local dev_type   = packet.data[3]
+
+        if comms_v ~= comms.version then
+            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                log.info(util.c("dropping coordinator establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+            end
+
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+        elseif dev_type == DEVICE_TYPE.CRD then
+            -- this is an attempt to establish a new coordinator session
+            local s_id = svsessions.establish_crd_session(nic, src_addr, i_seq_num, firmware_v)
+
+            if s_id ~= false then
+                println(util.c("CRD (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                log.info(util.c("CRD_ESTABLISH: CRD (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id, " on ", nic.phy_name()))
+
+                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW, { config.UnitCount, facility.get_cooling_conf() })
+            else
+                if last_ack ~= ESTABLISH_ACK.COLLISION then
+                    log.info("CRD_ESTABLISH: denied new coordinator [@" .. src_addr .. "] due to already being connected to another coordinator")
+                end
+
+                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.COLLISION)
+            end
+        else
+            log.debug(util.c("illegal establish packet for device ", dev_type, " on CRD channel"))
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+        end
+    end
+
+    -- handle a pocket debug establish
+    ---@param nic nic
+    ---@param packet mgmt_frame
+    ---@param src_addr integer
+    ---@param i_seq_num integer
+    ---@param last_ack ESTABLISH_ACK
+    local function _establish_pdg(nic, packet, src_addr, i_seq_num, last_ack)
+        local comms_v    = packet.data[1]
+        local firmware_v = packet.data[2]
+        local dev_type   = packet.data[3]
+
+        if comms_v ~= comms.version then
+            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                log.info(util.c("dropping PKT establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+            end
+
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+        elseif dev_type == DEVICE_TYPE.PKT then
+            -- this is an attempt to establish a new pocket diagnostic session
+            local s_id = svsessions.establish_pdg_session(nic, src_addr, i_seq_num, firmware_v)
+
+            println(util.c("PKT (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+            log.info(util.c("PDG_ESTABLISH: pocket (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id, " on ", nic.phy_name()))
+
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
+        else
+            log.debug(util.c("illegal establish packet for device ", dev_type, " on PKT channel"))
+            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
+        end
+
+    end
+
+    --#endregion
+
     -- PUBLIC FUNCTIONS --
 
     ---@class superv_comms
@@ -240,89 +419,45 @@ function supervisor.comms(_version, fp_ok, facility)
         local protocol  = packet.scada_frame.protocol()
         local i_seq_num = packet.scada_frame.seq_num()
 
-        if not nic then
+        if l_chan ~= config.SVR_Channel then
-            log.error("received packet from unconfigured interface " .. packet.scada_frame.interface(), true)
-        elseif l_chan ~= config.SVR_Channel then
             log.debug("received packet on unconfigured channel " .. l_chan, true)
         elseif r_chan == config.PLC_Channel then
             -- look for an associated session
             local session = svsessions.find_plc_session(src_addr)
 
-            if protocol == PROTOCOL.RPLC then
+            if session then
-                ---@cast packet rplc_frame
+                if nic ~= session.nic then
-                -- reactor PLC packet
+                    -- this is from the same device but on a different interface
-                if session ~= nil then
+                    -- drop unless it is a connection probe
+                    if (protocol == PROTOCOL.SCADA_MGMT) and (packet.type == MGMT_TYPE.PROBE) then
+                        ---@cast packet mgmt_frame
+                        log.debug(util.c("PROBE_ACK: conflict with PLC @", src_addr, " on ", session.nic.phy_name(), " probed on ", nic.phy_name()))
+                        _send_probe(nic, packet.scada_frame, PROBE_ACK.CONFLICT)
+                    else
+                        log.debug(util.c("unexpected packet for PLC @ ", src_addr, " received on ", nic.phy_name()))
+                    end
+                else
                     -- pass the packet onto the session handler
                     session.in_queue.push_packet(packet)
-                else
-                    -- any other packet should be session related, discard it
-                    log.debug("discarding RPLC packet without a known session")
                 end
+            elseif protocol == PROTOCOL.RPLC then
+                -- reactor PLC packet should be session related, discard it
+                log.debug("discarding RPLC packet without a known session")
             elseif protocol == PROTOCOL.SCADA_MGMT then
                 ---@cast packet mgmt_frame
                 -- SCADA management packet
-                if session ~= nil then
+                if packet.type == MGMT_TYPE.ESTABLISH then
-                    -- pass the packet onto the session handler
+                    -- establish a new session: validate packet and continue
-                    session.in_queue.push_packet(packet)
-                elseif packet.type == MGMT_TYPE.ESTABLISH then
-                    -- establish a new session
-                    local last_ack = self.last_est_acks[src_addr]
-
-                    -- validate packet and continue
                     if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                        local comms_v    = packet.data[1]
+                        _establish_plc(nic, packet, src_addr, i_seq_num, self.last_est_acks[src_addr])
-                        local firmware_v = packet.data[2]
-                        local dev_type   = packet.data[3]
-
-                        if comms_v ~= comms.version then
-                            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
-                                log.info(util.c("dropping PLC establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                            end
-
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
-                        elseif dev_type == DEVICE_TYPE.PLC then
-                            -- PLC linking request
-                            if packet.length == 4 and type(packet.data[4]) == "number" then
-                                local reactor_id = packet.data[4]
-
-                                -- check ID validity
-                                if reactor_id < 1 or reactor_id > config.UnitCount then
-                                    -- reactor index out of range
-                                    if last_ack ~= ESTABLISH_ACK.DENY then
-                                        log.warning(util.c("PLC_ESTABLISH: denied assignment ", reactor_id, " outside of configured unit count ", config.UnitCount))
-                                    end
-
-                                    _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                                else
-                                    -- try to establish the session
-                                    local plc_id = svsessions.establish_plc_session(nic, src_addr, i_seq_num, reactor_id, firmware_v)
-
-                                    if plc_id == false then
-                                        -- reactor already has a PLC assigned
-                                        if last_ack ~= ESTABLISH_ACK.COLLISION then
-                                            log.warning(util.c("PLC_ESTABLISH: assignment collision with reactor ", reactor_id))
-                                        end
-
-                                        _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.COLLISION)
-                                    else
-                                        -- got an ID; assigned to a reactor successfully
-                                        println(util.c("PLC (", firmware_v, ") [@", src_addr, "] \xbb reactor ", reactor_id, " connected"))
-                                        log.info(util.c("PLC_ESTABLISH: PLC (", firmware_v, ") [@", src_addr, "] reactor unit ", reactor_id, " PLC connected with session ID ", plc_id))
-                                        _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
-                                    end
-                                end
-                            else
-                                log.debug("PLC_ESTABLISH: packet length mismatch/bad parameter type")
-                                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                            end
-                        else
-                            log.debug(util.c("illegal establish packet for device ", dev_type, " on PLC channel"))
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                        end
                     else
                         log.debug("invalid establish packet (on PLC channel)")
                         _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
                     end
+                elseif packet.type == MGMT_TYPE.PROBE then
+                    -- connection probing
+                    log.debug(util.c("PROBE_ACK: reporting open to PLC @", src_addr, " probed on ", nic.phy_name()))
+                    _send_probe(nic, packet.scada_frame, PROBE_ACK.OPEN)
                 else
                     -- any other packet should be session related, discard it
                     log.debug(util.c("discarding PLC SCADA_MGMT packet without a known session from computer ", src_addr))
@@ -334,62 +469,43 @@ function supervisor.comms(_version, fp_ok, facility)
             -- look for an associated session
             local session = svsessions.find_rtu_session(src_addr)
 
-            if protocol == PROTOCOL.MODBUS_TCP then
+            if session then
-                ---@cast packet modbus_frame
+                if nic ~= session.nic then
-                -- MODBUS response
+                    -- this is from the same device but on a different interface
-                if session ~= nil then
+                    -- drop unless it is a connection probe
+                    if (protocol == PROTOCOL.SCADA_MGMT) and (packet.type == MGMT_TYPE.PROBE) then
+                        ---@cast packet mgmt_frame
+                        log.debug(util.c("PROBE_ACK: conflict with RTU_GW @", src_addr, " on ", session.nic.phy_name(), " probed on ", nic.phy_name()))
+                        _send_probe(nic, packet.scada_frame, PROBE_ACK.CONFLICT)
+                    else
+                        log.debug(util.c("unexpected packet for RTU_GW @ ", src_addr, " received on ", nic.phy_name()))
+                    end
+                else
                     -- pass the packet onto the session handler
                     session.in_queue.push_packet(packet)
-                else
-                    -- any other packet should be session related, discard it
-                    log.debug("discarding MODBUS_TCP packet without a known session")
                 end
+            elseif protocol == PROTOCOL.MODBUS_TCP then
+                ---@cast packet modbus_frame
+                -- MODBUS response, should be session related, discard it
+                log.debug("discarding MODBUS_TCP packet without a known session")
             elseif protocol == PROTOCOL.SCADA_MGMT then
                 ---@cast packet mgmt_frame
                 -- SCADA management packet
-                if session ~= nil then
+                if packet.type == MGMT_TYPE.ESTABLISH then
-                    -- pass the packet onto the session handler
+                    -- establish a new session: validate packet and continue
-                    session.in_queue.push_packet(packet)
-                elseif packet.type == MGMT_TYPE.ESTABLISH then
-                    -- establish a new session
-                    local last_ack = self.last_est_acks[src_addr]
-
-                    -- validate packet and continue
                     if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                        local comms_v    = packet.data[1]
+                        _establish_rtu_gw(nic, packet, src_addr, i_seq_num, self.last_est_acks[src_addr])
-                        local firmware_v = packet.data[2]
-                        local dev_type   = packet.data[3]
-
-                        if comms_v ~= comms.version then
-                            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
-                                log.info(util.c("dropping RTU establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                            end
-
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
-                        elseif dev_type == DEVICE_TYPE.RTU then
-                            if packet.length == 4 then
-                                -- this is an RTU advertisement for a new session
-                                local rtu_advert = packet.data[4]
-                                local s_id = svsessions.establish_rtu_session(nic, src_addr, i_seq_num, rtu_advert, firmware_v)
-
-                                println(util.c("RTU (", firmware_v, ") [@", src_addr, "] \xbb connected"))
-                                log.info(util.c("RTU_ESTABLISH: RTU (",firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
-                                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
-                            else
-                                log.debug("RTU_ESTABLISH: packet length mismatch")
-                                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                            end
-                        else
-                            log.debug(util.c("illegal establish packet for device ", dev_type, " on RTU channel"))
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                        end
                     else
                         log.debug("invalid establish packet (on RTU channel)")
                         _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
                     end
+                elseif packet.type == MGMT_TYPE.PROBE then
+                    -- connection probing
+                    log.debug(util.c("PROBE_ACK: reporting open to RTU_GW @", src_addr, " probed on ", nic.phy_name()))
+                    _send_probe(nic, packet.scada_frame, PROBE_ACK.OPEN)
                 else
                     -- any other packet should be session related, discard it
-                    log.debug(util.c("discarding RTU SCADA_MGMT packet without a known session from computer ", src_addr))
+                    log.debug(util.c("discarding RTU gateway SCADA_MGMT packet without a known session from computer ", src_addr))
                 end
             else
                 log.debug(util.c("illegal packet type ", protocol, " on RTU channel"))
@@ -398,107 +514,61 @@ function supervisor.comms(_version, fp_ok, facility)
             -- look for an associated session
             local session = svsessions.find_crd_session(src_addr)
 
-            if protocol == PROTOCOL.SCADA_MGMT then
+            if session then
+                if nic ~= session.nic then
+                    -- this is from the same device but on a different interface
+                    -- drop unless it is a connection probe
+                    if (protocol == PROTOCOL.SCADA_MGMT) and (packet.type == MGMT_TYPE.PROBE) then
                         ---@cast packet mgmt_frame
-                -- SCADA management packet
+                        log.debug(util.c("PROBE_ACK: conflict with CRD @", src_addr, " on ", session.nic.phy_name(), " probed on ", nic.phy_name()))
-                if session ~= nil then
+                        _send_probe(nic, packet.scada_frame, PROBE_ACK.CONFLICT)
+                    else
+                        log.debug(util.c("unexpected packet for CRD @ ", src_addr, " received on ", nic.phy_name()))
+                    end
+                else
                     -- pass the packet onto the session handler
                     session.in_queue.push_packet(packet)
-                elseif packet.type == MGMT_TYPE.ESTABLISH then
+                end
-                    -- establish a new session
+            elseif protocol == PROTOCOL.SCADA_MGMT then
-                    local last_ack = self.last_est_acks[src_addr]
+                ---@cast packet mgmt_frame
-
+                -- SCADA management packet
-                    -- validate packet and continue
+                if packet.type == MGMT_TYPE.ESTABLISH then
+                    -- establish a new session: validate packet and continue
                     if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                        local comms_v    = packet.data[1]
+                        _establish_crd(nic, packet, src_addr, i_seq_num, self.last_est_acks[src_addr])
-                        local firmware_v = packet.data[2]
-                        local dev_type   = packet.data[3]
-
-                        if comms_v ~= comms.version then
-                            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
-                                log.info(util.c("dropping coordinator establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                            end
-
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
-                        elseif dev_type == DEVICE_TYPE.CRD then
-                            -- this is an attempt to establish a new coordinator session
-                            local s_id = svsessions.establish_crd_session(nic, src_addr, i_seq_num, firmware_v)
-
-                            if s_id ~= false then
-                                println(util.c("CRD (", firmware_v, ") [@", src_addr, "] \xbb connected"))
-                                log.info(util.c("CRD_ESTABLISH: coordinator (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
-
-                                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW, { config.UnitCount, facility.get_cooling_conf() })
-                            else
-                                if last_ack ~= ESTABLISH_ACK.COLLISION then
-                                    log.info("CRD_ESTABLISH: denied new coordinator [@" .. src_addr .. "] due to already being connected to another coordinator")
-                                end
-
-                                _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.COLLISION)
-                            end
-                        else
-                            log.debug(util.c("illegal establish packet for device ", dev_type, " on coordinator channel"))
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                        end
                     else
                         log.debug("CRD_ESTABLISH: establish packet length mismatch")
                         _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
                     end
+                elseif packet.type == MGMT_TYPE.PROBE then
+                    -- connection probing
+                    log.debug(util.c("PROBE_ACK: reporting open to CRD @", src_addr, " probed on ", nic.phy_name()))
+                    _send_probe(nic, packet.scada_frame, PROBE_ACK.OPEN)
                 else
                     -- any other packet should be session related, discard it
                     log.debug(util.c("discarding coordinator SCADA_MGMT packet without a known session from computer ", src_addr))
                 end
             elseif protocol == PROTOCOL.SCADA_CRDN then
                 ---@cast packet crdn_frame
-                -- coordinator packet
+                -- coordinator packet,  should be session related, discard it
-                if session ~= nil then
-                    -- pass the packet onto the session handler
-                    session.in_queue.push_packet(packet)
-                else
-                    -- any other packet should be session related, discard it
                 log.debug(util.c("discarding coordinator SCADA_CRDN packet without a known session from computer ", src_addr))
-                end
             else
-                log.debug(util.c("illegal packet type ", protocol, " on coordinator channel"))
+                log.debug(util.c("illegal packet type ", protocol, " on CRD channel"))
             end
         elseif r_chan == config.PKT_Channel then
             -- look for an associated session
             local session = svsessions.find_pdg_session(src_addr)
 
-            if protocol == PROTOCOL.SCADA_MGMT then
+            if session then
-                ---@cast packet mgmt_frame
-                -- SCADA management packet
-                if session ~= nil then
                 -- pass the packet onto the session handler
                 session.in_queue.push_packet(packet)
-                elseif packet.type == MGMT_TYPE.ESTABLISH then
+            elseif protocol == PROTOCOL.SCADA_MGMT then
-                    -- establish a new session
+                ---@cast packet mgmt_frame
-                    local last_ack = self.last_est_acks[src_addr]
+                -- SCADA management packet
-
+                if packet.type == MGMT_TYPE.ESTABLISH then
-                    -- validate packet and continue
+                    -- establish a new session: validate packet and continue
                     if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                        local comms_v    = packet.data[1]
+                        _establish_pdg(nic, packet, src_addr, i_seq_num, self.last_est_acks[src_addr])
-                        local firmware_v = packet.data[2]
-                        local dev_type   = packet.data[3]
-
-                        if comms_v ~= comms.version then
-                            if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
-                                log.info(util.c("dropping PDG establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                            end
-
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
-                        elseif dev_type == DEVICE_TYPE.PKT then
-                            -- this is an attempt to establish a new pocket diagnostic session
-                            local s_id = svsessions.establish_pdg_session(nic, src_addr, i_seq_num, firmware_v)
-
-                            println(util.c("PKT (", firmware_v, ") [@", src_addr, "] \xbb connected"))
-                            log.info(util.c("PDG_ESTABLISH: pocket (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
-
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.ALLOW)
-                        else
-                            log.debug(util.c("illegal establish packet for device ", dev_type, " on pocket channel"))
-                            _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
-                        end
                     else
                         log.debug("PDG_ESTABLISH: establish packet length mismatch")
                         _send_establish(nic, packet.scada_frame, ESTABLISH_ACK.DENY)
@@ -509,14 +579,8 @@ function supervisor.comms(_version, fp_ok, facility)
                 end
             elseif protocol == PROTOCOL.SCADA_CRDN then
                 ---@cast packet crdn_frame
-                -- coordinator packet
+                -- coordinator packet, should be session related, discard it
-                if session ~= nil then
-                    -- pass the packet onto the session handler
-                    session.in_queue.push_packet(packet)
-                else
-                    -- any other packet should be session related, discard it
                 log.debug(util.c("discarding pocket SCADA_CRDN packet without a known session from computer ", src_addr))
-                end
             else
                 log.debug(util.c("illegal packet type ", protocol, " on pocket channel"))
             end