[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now


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

Posted on 2004-10-26
Medium Priority
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 is...my 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 Express...it succesfull..
3-When I try to connect the ADSL modem to D-Link router dirextly and try to send email attachment from wireless client...it 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
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3

Author Comment

ID: 12421772
LVL 51

Expert Comment

ID: 12425599
does this only happen if the firewall (iptables) is active? then the missing port 25 might be the problem

Author Comment

ID: 12425922
yeah...happen when iptables firewall is active...the port 25 you mean i need to allow tcp and udp for port 25?...i try
Put Machine Learning to Work--Protect Your Clients

Machine learning means Smarter Cybersecurity™ Solutions.
As technology continues to advance, managing and analyzing massive data sets just can’t be accomplished by humans alone. It requires huge amounts of memory and storage, as well as the high-speed power of the cloud.

LVL 51

Expert Comment

ID: 12431231
tcp port 25 should be sufficient

Author Comment

ID: 12433574
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

ahoffmann earned 200 total points
ID: 12439040
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

ID: 12441001
ok thanks....is  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,,

Featured Post

Are You Ready for GDPR?

With the GDPR deadline set for May 25, 2018, many organizations are ill-prepared due to uncertainty about the criteria for compliance. According to a recent WatchGuard survey, a staggering 37% of respondents don't even know if their organization needs to comply with GDPR. Do you?

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Do you have a windows based Checkpoint SmartCenter for centralized Checkpoint management?  Have you ever backed up the firewall policy residing on the SmartCenter?  If you have then you know the hassles of connecting to the server, doing an upgrade_…
This article offers some helpful and general tips for safe browsing and online shopping. It offers simple and manageable procedures that help to ensure the safety of one's personal information and the security of any devices.
This tutorial will teach you the special effect of super speed similar to the fictional character Wally West aka "The Flash" After Shake : http://www.videocopilot.net/presets/after_shake/ All lightning effects with instructions : http://www.mediaf…
Have you created a query with information for a calendar? ... and then, abra-cadabra, the calendar is done?! I am going to show you how to make that happen. Visualize your data!  ... really see it To use the code to create a calendar from a q…
Suggested Courses

656 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question