Author Topic: DNS resolution...strange problem?  (Read 600 times)

Dariusz Piatkowski

  • Sr. Member
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 6
  • Posts: 266
    • View Profile
DNS resolution...strange problem?
« on: May 02, 2017, 06:22:13 am »
So I'm a little stumped by the behaviour I am seeing, granted, I am a stranger to the "belly" of the TCP/IP beast!

Alright...so I've got a dynamic IP address account at no-ip.org, specifically "darico.no-ip.org" which normally resolves to my OS/2 machine. The router has port 80 mapping to my local static IP address for my OS2 box. The update of the darcio.no-ip.org host is done by my router as soon as the ISP assigned IP address changes, so this is automated and works reliably.

Recently I upgraded my no-ip.org to an Enhanced account and registered a domain (skokconsulting.com), which now allows me to re-direct additional traffic to one of the machine on my home network. This is all controlled through the router's port mapping functionality.

Here is where things are going "strange"...LOL: in a firefox session on my OS2 box I can not resolve neither the darcio.no-ip.org nor www.skokconsulting.com to the real OS2 box IP address. Instead darcio.no-ip.org it gets mapped to a weird looking re-direct, that being: http://www.skokconsulting.com:81/. Of course there is nothing out there listening on port 81, so this never connects. The www.skokconsulting.com gets resolved to 98.143.71.19 IP address...again, no idea where this is coming from. I do not have any of these in my HOSTS file!

What I can not figure out is how this re-direct of "darcio.no-ip.org" to "http://www.skokconsulting.com:81/" happens? There is nothing on noip.org server that does this...in fact I can confirm that the correct re-direct is done when I access both of these hosts from one of my Wintel boxes, so this leads me to believe there is something specific to either the OS/2 tcp/ip config, or to firefox itself that is doing this...just no idea where to even look ???



ivan

  • Hero Member
  • *****
  • Thank You
  • -Given: 0
  • -Receive: 24
  • Posts: 627
    • View Profile
Re: DNS resolution...strange problem?
« Reply #1 on: May 02, 2017, 03:39:27 pm »
Why are you trying to connect two boxes that are both on the same network by going out to the web and back again?  That is asking for problems when all you need to do is use the local IP address for the box you want to contact.

An example of this is when I connect to one of our NAS units http servers by using, for example, http://192.168.0.100 in the firefox address bar.

Ian Manners

  • Global Moderator
  • Full Member
  • *****
  • Thank You
  • -Given: 29
  • -Receive: 17
  • Posts: 238
  • I am the computer, it is me.
    • View Profile
    • OS/2 Site
Re: DNS resolution...strange problem?
« Reply #2 on: May 02, 2017, 06:27:48 pm »
Hi Dariusz,

Been a long time since I used hosts as such, I use BIND with internet and external views but..

do you have "SET USE_HOSTS_FIRST=1" in your config.sys ?
Also what do you have in x:\mptn\etc\RESOLV2 ?

Cheers
Ian B Manners

roberto

  • Sr. Member
  • ****
  • Thank You
  • -Given: 13
  • -Receive: 6
  • Posts: 292
    • View Profile
Re: DNS resolution...strange problem?
« Reply #3 on: May 02, 2017, 08:30:35 pm »
I have not any problem now,
[E:\]host darcio.no-ip.org
darcio.no-ip.org =   216.8.135.50

[E:\]host www.skokconsulting.com
www.skokconsulting.com =   216.8.135.50
saludos
roberto

Dariusz Piatkowski

  • Sr. Member
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 6
  • Posts: 266
    • View Profile
Re: DNS resolution...strange problem?
« Reply #4 on: May 03, 2017, 03:01:13 am »
Hi Ivan,

Why are you trying to connect two boxes that are both on the same network by going out to the web and back again?...

If all I was trying to do is to access the machines locally you would be absolutely correct. In my case I am hosting some apps on my internal network and need to be able to get to them from outside of my LAN.

The fact that I am accessing them from a local machine in this case should make no difference, meaning, the DNS resolution should still happen and even though it is the "long way" around the connection should still come back to my internal network through the router.

Dariusz Piatkowski

  • Sr. Member
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 6
  • Posts: 266
    • View Profile
Re: DNS resolution...strange problem?
« Reply #5 on: May 03, 2017, 03:04:23 am »
Hi Roberto,

I have not any problem now,
[E:\]host darcio.no-ip.org
darcio.no-ip.org =   216.8.135.50

[E:\]host www.skokconsulting.com
www.skokconsulting.com =   216.8.135.50

Thank you for the check, you are seeing what I'm expecting to see as well.

In fact, from an OS/2 CLI I get the following:

=== START ===

[G:\]tracerte www.skokconsulting.com
traceroute to www.skokconsulting.com (216.8.135.50), 30 hops max, 38 byte packets

[G:\]tracerte darcio.no-ip.org
traceroute to darcio.no-ip.org (216.8.135.50), 30 hops max, 38 byte packets

=== STOP ===

So I have a successfull resolution at tcp/ip level, but it is FF that appears to have this screwed up somehow...LOL!

Dariusz Piatkowski

  • Sr. Member
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 6
  • Posts: 266
    • View Profile
Re: DNS resolution...strange problem?
« Reply #6 on: May 03, 2017, 03:06:39 am »
Hi Ian,

do you have "SET USE_HOSTS_FIRST=1" in your config.sys ?
Also what do you have in x:\mptn\etc\RESOLV2 ?

Yes, that SET is what I use in my CONFIG.SYS, there are no entries matching what I see FF resolving to in my HOSTS file either.

Here are the contents of my RESOLV2, they match what the TCP/IP Settings notebook shows:

=== START ===

[G:\mptn\etc]type resolv2
domain mnsi.net
nameserver 8.8.8.8
nameserver 216.8.137.203
nameserver 216.8.137.204

=== STOP ===

Dariusz Piatkowski

  • Sr. Member
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 6
  • Posts: 266
    • View Profile
Re: DNS resolution...strange problem?
« Reply #7 on: May 03, 2017, 03:15:31 am »
Whoa!!!! Found the problem...

I went through the process of purging the FF native DNS cache...that did not resolve my issue, so then it hit me "...hey, what if the page just keeps on re-loading the cached version...?". In hindsight it sort of seems almost too-obvious. Well, my cache was currently 340 MB in size, having purged it my problem went away...holy smokes!!!