RV042 Port Forwarding

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by scotje, Jul 12, 2007.

  1. scotje

    scotje Guest

    This seems like it should be pretty simple, but I cannot convince this RV042 we just got to forward port 25 to our LAN mail server.

    Firmware version : (Feb 12 2007 10:43:08)

    Here's how things are set up right now:

    WAN1: (connects to Actiontec GT701 DSL Modem on
    WAN2: Disabled for the moment, although there is another identical Actiontec DSL modem that I'll hook back up once I get forwarding working.)

    The Actiontec modem has a static IP address from our ISP and I decided the easiest thing to do was to just set up as the DMZ host for the DSL modem, that way all incoming connections are just sent straight to the RV042.

    On the RV042, I have port forwarding set up for SMTP (TCP/25) set to forward to (our mail server IP address):

    SMTP TCP 25~25 Enabled

    I have also put in a firewall access rule to allow this traffic:

    smtp Allow SMTP [25] * Any ~ Always

    To test things, I SSH into a remote server and then attempt to use telnet to connect to our static IP addres on port 25. The connection always times out.

    The packets are clearly making it to the RV042 as evidenced by these entries in the firewall log:

    Jul 12 08:05:05 2007 Connection Accepted TCP 208.xxx.xxx.109:49061-> on ixp1

    But from there the packets just seem to be lost. I don't see any evidence in the mail server logs that it ever sees the connection attempt.

    Anyone have any suggestions on what I might be doing wrong? Port forwarding on our old Netgear router is working fine.
  2. pablito

    pablito Network Guru Member

    Does the mail server use the RV as the default gateway?
  3. YeOldeStonecat

    YeOldeStonecat Network Guru Member

    Shouldn't need the additional ACL since you have it wide open, only need that if clamping down access to a limited IP/IP range. Port forwarding will do it by itself. Try clearing the ACL, leave it on just port forwarding..and see if that works?

    Although I never double NAT my setups, I always bridge the modems.
  4. sebadamus

    sebadamus LI Guru Member

    Hello, I have been using some linksys devices... this time with the RV042. My question is why I cant do port forwarding from an external port to another diferent internal port.


    ExternalIP:14000 --- to --- InternalIP:40000

    This is usefull, at least for me :-D

    Can you help me? may be there is some way...


  5. gedisweb

    gedisweb LI Guru Member

    Hello Sebastian,

    There is a way but you need to configure three parts.

    Example: you have a service running in one PC of your LAN in the port 40000 but externally you want the port 14000.

    1) go to linksys rv042 web manager
    2) go to setup/Forwarding
    3) add a new service (i.e. myservice (tcp/14000) (note: external port)
    4) add a new forward with the new service to the internal IP of the PC running the service in port 40000 (i.e.
    5) In the bottom of the same page there is "port triggering". Add a new application with some name (i.e. myservice), Trigger Port Range 40000:40000 (internal port), Incoming Port Range 14000:14000 (external port)
    6) Click on "Save Settings"
    7) go to setup/uPnP and mark Yes if not
    8) add a new service myservice external port, internal port (i.e. myservice(tcp/14000->40000))
    9) add a new line using the new service and assing it to the internal IP of the PC running the service (i.e.
    10) Click on "Save Settings"

    Now all traffic incoming at port 14000 will be forwarded to the PC in at port 40000.

    It is a bit complicated but it works fine for me.

    Hope it can help you
  6. pablito

    pablito Network Guru Member

    Does the Rv042 have UPnP forwarding like the RV082 and RV016? it looks and acts like port forwarding except you can specify internal and external ports and via firewall rules can restrict access (port forwarding allows all).
    note: you can setup UPnP rules but leave the UPnP server off.
  7. d__l

    d__l Network Guru Member

    pablito, according to the various RV042 simulators, its UPnP page is identical to that of the RV082.

    gedisweb could have left half the set up steps off that description and the "ExternalIP:14000 --- to --- InternalIP:40000" could have been completely set up on the UPnP page (... and leave the UPnP Function disabled too).
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