how to set/change gateway setting or make it accept connection from different subnet

[David_Wu]

I noticed the gatewy settings in IP Config in RTCS menu in CW10.2

gateways

  network                         gateway

  0.0.0.0/0                       192.168.100.1

  192.168.1.102/32       192.168.1.102

My configuration is: DHCP enabled - got an IP 192.168.100.185, gateway 192.168.100.1, netmask 255.255.255.0.

I can connect 192.168.100.185  from 192.168.100.4 - same subnet - but I couldn't from 192.168.1.102

Anyone know if the gateway setting is correct in MQX RTCS and if not how to change it? (I know how to set the default gateway - I don't know how to change the extra gateway info above -). Why there is an extra routing entry?

what settings can make it accept a connection from a different subnet - timeout issue, routing issue, socket option issue , what ever to make it work?

thanks in advance,

David 

[GottiLuca]

Dear David,

It's quite normal that you could not connect to another subnet .

In such cases you have two options :

- You can try to connect the two nodes directly ( i.e. : without using gateway ) increasing the  netmask from 255.255.255.0 to a larger one ( i.e. : 255.255.0.0 ). In such a case, you have to set this same netmask on the other node ( 192.168.1.102 ).

- if you don't wanna modify the netmask, you muast have a gateway ( 192.168.100.1 ) that routes the messages bidirectonally from the two subnets ( 192.168.100.x and 192.168.1.x ) . This is usually a functionality that requires a routers or , more appropriate ,a firewall .

[David_Wu]

updates:It seems there is no route back to the host that makes the connection. I got the error is:TCP: TCP_Send_IP_packet: errno 1510 on IP_send.If I change the netmask to accommodate two subnets then the TCP connection works. Further investigation indicates that it looks like MQX did not support ICMP redirect messages from gateway.

[David_Wu]

By changing the netmask is only a work around and not a fix - I'd like to know if the MQX team will find a solution?

[butok]

The communication between two nodes from different networks is done via a gateway.

Nodes can communicates directly (without gateway) only if they belong to the same network. It is defined by the netmask.

[David_Wu]

But when it comes to ICMP redirct, things changed. If the Default gateway tells the K60 to contact the end device directly then regardless the netmask, K60 should setup a ROUTING rule for it to reach.

Here is what I did as a work around (add a indirect routing rule):

in icmp.c for case ICMPTYPE_REDIRECT in ICMP_service() I add the detection for redirect for a host and call RTCSCMD_internal(parms, IPIF_gate_add_redirect_other) instead - IPIF_gate_add_redirect_other is the function I added in ipif_add.c (see below ) - note that I add two more parameters in IP_route_add_indirect(). Also in IP_route_test() I check for RTF_REDIRECT_HOST flag and return the correct info if match.

I might miss some source code - but you should get the idea.

-----------------

icmp.c

------------------

@@ -99,7 +99,7 @@

    _ip_address          source, dest;

    uint_32              error;

    uint_16              chksum;

-   uchar                type;

+   uchar                type, code;

    ICMP_cfg_ptr = RTCS_getcfg(ICMP);

@@ -109,6 +109,7 @@

    source = IP_source(pcb);

    dest   = IP_dest(pcb);

    type = ntohc(packet->TYPE);

+   code = ntohc(packet->CODE);

    /*

    ** Make sure that

@@ -170,6 +171,14 @@

             parms.network = origdest;

             parms.netmask = 0xFFFFFFFFL;

             parms.locmask = 0;

+#define ICMP_REDIRECT_FIX 1

+#if ICMP_REDIRECT_FIX //WMQ

+            parms.ihandle = pcb->IFSRC;

+            if(code == ICMPCODE_RD_HOST){

+               parms.address = dest;

+               RTCSCMD_internal(parms, IPIF_gate_add_redirect_other);

+            } else

+#endif

             RTCSCMD_internal(parms, IPIF_gate_add_redirect);

          } else {

             IF_ICMP_STATS_ENABLED(ICMP_cfg_ptr->STATS.COMMON.ST_RX_DISCARDED++);

---------------------------------------

rtcs/source/tcpip/ipif_add.c

-----------------------------------------    

+/* for ICMP redirect when gateway is the destination */

+void IPIF_gate_add_redirect_other

+   (

+      IPIF_PARM_PTR  parms

+   )

+{ /* Body */

+

+#if RTCSCFG_ENABLE_IP4

+

+   _ip_address          netmask = parms->netmask;

+   uint_32              error;

+

+   /*

+   ** Make sure the netmask is valid.  We use the fact that

+   ** (x & x+1) == 0  <=>  x = 2^n-1.

+   */

+   if (~netmask & (~netmask + 1)) {

+      RTCSCMD_complete(parms, RTCSERR_IP_BIND_MASK);

+      return;

+   } /* Endif */

+

+   /* Start CR 1133 */

+   //error = IP_route_add_direct(parms->address, parms->netmask, (IP_IF_PTR)parms->ihandle, (IP_IF_PTR)parms->ihandle); /* this one causes memory leak*/

+   error = IP_route_add_indirect(parms->network, netmask, parms->network, RTF_REDIRECT | RTF_REDIRECT_HOST, parms->locmask, (IP_IF_PTR)parms->ihandle,parms->address);

+

+   RTCSCMD_complete(parms, error);

+#else

+

+    RTCSCMD_complete(parms, RTCSERR_IP_IS_DISABLED);

+

+#endif /* RTCSCFG_ENABLE_IP4 */   

+

+} /* Endbody */

--------------------------------------------

rtcs/source/tcpip/iproute.c

--------------------------------------------

uint_32 IP_route_add_indirect

   (

      _ip_address    address,    /* Gateway address */

@@ -373,7 +373,9 @@

       _ip_address    netmask,    /* Network mask    */

       _ip_address    network,    /* Network address */

       uint_32        flag,       /* [IN] RTF_* */

-      uint_16        metric      /* [IN] the route metric [0,65535] */

+      uint_16        metric,     /* [IN] the route metric [0,65535] */

+      IP_IF_PTR      destif,     /* WMQ:Interface for outgoing packets  */

+      _ip_address    source      /* WMQ: source address to send */

    )

{ /* Body */

    IP_CFG_STRUCT_PTR                IP_cfg_ptr = RTCS_getcfg(IP);

@@ -390,6 +392,8 @@

    route->FLAGS      = flag | RTF_UP;

    route->IS_DIRECT  = NULL;

    route->METRIC     = metric;

+   route->DESTIF     = destif; //WMQ

+   route->ADDRESS    = source; //WMQ

-------------------------------------------

static boolean IP_route_test

   (

      pointer     node_data,

      pointer     data

   )

{ /* Body */

.....

   if (indirect && testdata->check_gateway) {

      do {

          if (indirect->FLAGS & RTF_UP) {

            testdata->hopdest = indirect->GATEWAY;

#if 1

            if(indirect->FLAGS & RTF_REDIRECT_HOST){

                testdata->sendit = TRUE;

                testdata->ifdest = indirect->DESTIF;

                testdata->retval = RTCS_OK;

                if (!testdata->hopsrcislocal) {

                   testdata->hopsrc = indirect->ADDRESS;

                } /* Endif */

           }

#endif

            /* Notify calling function that a gateway was found */

            testdata->check_gateway = FALSE;

            return TRUE;

          } /* Endif */

         indirect = indirect->NEXT;

      } while(indirect != route->INDIRECT);

---------------------------------------------

rtcs/source/include/ip_prv.h

---------------------------------------------

#define RTF_REDIRECT_HOST

0x0008

/* created for a ICMP redirect for a host*/

[butok]

Hi David,

We have never tested handling of the ICMPv4 Redirect messages. So I have added the task to our backlog.

BTW: What have you used to produce the ICMPv4 redirect messages? Do you use a special/customizable switch?

Thanks,

Andrey

[David_Wu]

The easiest way to instrument this is to enable a Linux PC with two Ethernet(s) to act as your network gateway

On LINUX PC (acting as Router/Gateway)

Ethernet 1   (Ethernet link to real network gateway 192.168.0.1 <=> 192.168.0.100 )

ifconfig eth0 192.168.0.1 netwmask 255.255.255.0

route add default gw 192.168.0.100

Ethernet 2  ( Ethernet support two seperare class C Lan spaces 192.168.1.1/24 and 192.168.100.1/24 ) connected to a HUB or a SWITCH

ifconfig  eth1:0   192.168.1.1 netmask 255.255.255.0

route add 192.168.1.0/24 eth1

ifconfig  eth1:1   192.168.100.1 netmask 255.255.255.0

route add 192.168.100.0/24 eth1

Ensure you enable the LINUX mahine as a router.  You can do this typically through the /proc file system.

Enable IP Forwarding like such:

echo 1 >  /proc/sys/net/ipv4/ip_forward

See the link below for information on enable the sending of redirects based on interface and network load. 

http://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.kernel.obscure.html