Solved

Problem with opening ports for ftp in iptables

Posted on 2014-07-31
4
481 Views
Last Modified: 2014-08-01
Hi all,  If I have INPUT chain set to drop by default, and ports 20 and 21 are open, ftp doesn't work right.  I've also noticed the SSH password prompt takes a long time to show up. When I accept all input again, ftp works, and the login pops up right away. The problem with ftp is that it connects, but doesn't show any data (no directory listing once it lists). I'm using a default installation and settings (except anonymous login is off) for vsftp.  The only input rules I have are 20, 21, and my ssh port open and I set an accept all on the lo interface.  My output is set to accept.

Does anyone know what I'm doing wrong or why this isn't working?
0
Comment
Question by:kendalltech
[X]
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 Comments
 
LVL 29

Accepted Solution

by:
Jan Springer earned 500 total points
ID: 40231790
questions:

1) is vsftpd configured to allow passive ftp?  if yes, you will need to update iptables_config with the conntrack_ftp

2) is sshd_config configured to do DNS lookups?  if yes and they are not resolving, then that will also cause a delay
0
 
LVL 62

Expert Comment

by:gheist
ID: 40231798
You should stop checking reverse DNS, that will cure waits.
nobody ever will connect to your port 20
you need either to load nf_conntrack_ftp ur agree between iptables, ephemeral ports and ftp server which ports to use for incoming PASV connections
0
 
LVL 12

Expert Comment

by:Kent W
ID: 40231997
Do you have port 53 outgoing open so you can do recursive lookups?
See if you can resolve anything from within the machine while your iptables rules are in place, especially your OUTPUT rules.
0
 
LVL 2

Author Closing Comment

by:kendalltech
ID: 40233574
Thanks, both problems are solved now.
0

Featured Post

 Database Backup and Recovery Best Practices

Join Percona’s, Architect, Manjot Singh as he presents Database Backup and Recovery Best Practices (with a Focus on MySQL) on Thursday, July 27, 2017 at 11:00 am PDT / 2:00 pm EDT (UTC-7). In the case of a failure, do you know how long it will take to restore your database?

Question has a verified solution.

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

Over the last ten+ years I have seen Linux configuration tools come and go. In the early days there was the tried-and-true, all-powerful linuxconf that many thought would remain the one and only Linux configuration tool until the end of times. Well,…
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.
Learn how to navigate the file tree with the shell. Use pwd to print the current working directory: Use ls to list a directory's contents: Use cd to change to a new directory: Use wildcards instead of typing out long directory names: Use ../ to move…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
Suggested Courses

635 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