We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you two Citrix podcasts. Learn about 2020 trends and get answers to your biggest Citrix questions!Listen Now

x

Masquerading and diald

wilt
wilt asked
on
Medium Priority
304 Views
Last Modified: 2010-03-17
I have a local ethernet network with ip masquerading and diald. My problem is that when I try to gain access to a local machine diald brings up my ISP. I think that my problem is in my routing setup. My ip address's are 192.168.1.1 for the server and 192.168.1.2 for the host. My ISP account is dynamic ppp. Any help would be greatly appreciated !!!!!
Comment
Watch Question

Commented:
I had exactly the same problem as this. In 99% of cases, I have found that it's DNS traffic that causes the problem. Make sure your hosts files list all you local machines. The make sure you don't have hosts.allow or hosts.deny files clogging things up.

Many protocols do something like the following

Client quieries DNS for servers address
Client connects to server
Server does revers lookup on client to ensure that clients claimed IP address is the same as the DNS's IP address for client's hostname.

This is a security enhancement and is usually transparent, but with diald.....

the r utilities are affected by this behaviour, among other things. f you have hosts.allow and hosts.deny files containing hostnames, it does this for everything.

What you can do is run tcpdump -i ppp0 on your masquerading machine, then try something which shouldn't bring the linl up, but does. This will show you the packet traffic across the link, which should help you pinpoint it. Be aware that tcpdump itself will do DNS lookups to be able to show you hostnames not IP addresses, so you'll have some extra packets originating from the masquerading machine. There's an option to tcpdump that will tell it to show numerical IP's, and will stop this behaviour.

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.