Can't send email attachment behind linux router and D-Link router

Posted on 2004-10-26
Last Modified: 2010-04-09
I have a linux router with 2NIC plus with iptables firewall and snort....eth0 is connected to my ADSL modem...and eth1 connected to my DI-714P+ router at WAN port by using cross cable. DI-714P+ is D-Link wireless router.

1-My problem wireless client cannot send email with attachment...
2-I try to connect directly from eth1 to a single pc ( XP ), and try to send email with attachment using Outlook succesfull..
3-When I try to connect the ADSL modem to D-Link router dirextly and try to send email attachment from wireless succesfull...
3-I think my firewall is ok because i already open port for outgoing email in the firewall setting like below:
OPEN_TCP="20 21 110 143"
OPEN_UDP="20 21 110 143"

I use arno-iptables-firewall-1.8.2a-stable.tgz

Thank you.
Question by:ftpfreak

    Author Comment

    LVL 51

    Expert Comment

    does this only happen if the firewall (iptables) is active? then the missing port 25 might be the problem

    Author Comment

    yeah...happen when iptables firewall is active...the port 25 you mean i need to allow tcp and udp for port 25?...i try
    LVL 51

    Expert Comment

    tcp port 25 should be sufficient

    Author Comment

    now my client can send email attachment after i do this:

    linux router -(connect from eth0 to vpn router WAN port)- > d-link vpn router -(connect from Lan at vpn router to WAN port)-> dlink wireless router -> wireless client

    but when i use this, my client cannot send email with attchment...

    linux router - >d-link wireless router -> wireless client

    i try to reset the wireless router and just use the basic configuration...the problem is still the same...

    what do you think?
    LVL 51

    Accepted Solution

    check both packetfilter: iptables on linux and whatever you have in d-link
      tcpdump -l -n -i eth0
    to get a glue what's going on, if you donÄt see connections to port 25, it's most likely a firwall (d-link) problem

    Author Comment

    ok  it normall when we do a linux router...eth0 connect to internet and eth1 is connect to d-link wan port by using cross cable...the internet at d-link will be not stable...up and down,,

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