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Firewall on WRT54 - FTp server problems

Discussion in 'Networking Issues' started by johannlo, Sep 2, 2005.

  1. johannlo

    johannlo Guest

    Hi All

    Trying to setup a FTP server behind a WRT54G. The WRT54G is connected to the net via ADSL modem in half bridge mode (ie handles PPPoE, bridges IP packets so the WRT is assigned its WAN IP from the ISP's DHCP).

    I've opened up port 21 on the FTP box (running fedora core 4) and it works fine if I FTP in from a windows machine on the LAN.

    It also appears to work fine via the windows machine if I use the web address (dynamic DNS, confirmed OK via telnet tests to router - I've turned this off now!). However testing from another site failed, couldn't even connect.

    I've forwarded port 20-22 (FTP + SSH) on the Linksys to the lan IP of the FTP box, but I'm thinking I might need to configure the firewall on the linux box further (e.g. the high ports that FTP uses)? Would this be done via the command line on the router, and what commands do I use? (what firewall is it? Iptables? Ipchains? etc.)

    Any advice would be appreciated.
  2. 4Access

    4Access Network Guru Member

    Are you sure the other site isn't filtering FTP traffic on their end? Usually if you have the control port (21) forwarded properly you will at least be able to connect. (Did it prompt you for a user name and password? If not then I'd suspect either a problem with your port 21 forwarding rule or filtering at the remote site.)

    If you are able to get a connection from the remote site but are having trouble transfering files make sure the FTP client is operating in passive mode.

    In passive mode the after the initial connection to port 21 the FTP server will open another (high numbered random) port and tell the client to connect there for the data. In active mode the reverse happens: After the initial connection to the control port the client opens a high numbered port and tells the server to connect to it to send the data. The problem with an active connection is that firewalls & routers etc at the client's site may filter the incoming connection from the FTP server.

    Good luck.

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