Results tagged “/etc/resolv.conf” from CLICK

I don't begin to fully understand how computer networking works, but I can pretty much hack my way through it. (My networking "goal" is to set up VNC over the Internet ... but that's light years ahead of where I am today.) And I'm sure I've had this very same problem before (and should probably just try to find an earlier blog entry with the very same problem/solution instead of reinventing a very squeaky, annoying wheel with all you dear readers.

But if I'm having this problem again, chances are some of you might have it, too. And I don't think it's confined to OpenBSD. This could potentially crop up in any number of Linux distributions.

Here's the problem: For the past few days, my OpenBSD laptop has been slow as sludge in the browser (Firefox and Opera are the same in this regard).

But a speed test or a download of a large file shows no connection problem or speed problem at all.

So what is making my Web browsing so slow?

The answer: A bad nameserver in my /etc/resolv.conf file.

You see, I don't use this laptop in a single location. I have it at home, at the office, at Starbucks, and any number of places in between where I connect either wirelessly or with wired Ethernet.

And I usually do it with dynamic IPs, meaning I have OpenBSD set to get a dynamic IP address from the router providing me with networking, be it my home router or any other.

And my home router, a recent Netgear model, doesn't just pass through the two nameservers from my ISP that I have programmed into it. Instead it gives my laptop the nameserver address 192.168.1.1 (the same IP address as the router itself). I assume that the router is making some kind of translation and pushing the nameserver data through the 192.168.1.1 IP address to my laptop.

For the most part this works. And forgive me if the following explanation is either totally wrong or just incomplete. I'm explaining it the way I understand it, and I welcome your clarification and correction:

Usually when a router sets up a dynamic connection, it sends the router's gateway IP to the local machine, assigns the machine its own IP address and provides nameserver data (i.e. the IP address of the nameserver) as well.

So the local machine now knows the router/gateway address (and subnet), local IP address and nameserver address.

But ... one of the networks to which I connect is a bit old school. The router gives me a dynamic IP but doesn't send nameserver data. It assumes that the local machine already has nameserver data entered into the system and doesn't modify /etc/resolv.conf at all. Hence my old nameserver IP address — 192.168.1.1 — is still at the top of /etc/resolv.conf, with my "real" DNS nameserver IPs below it.

And the reason it takes so long for Web pages to appear is that the system is trying to resolve every alphanumeric HTTP address through a DNS server that on this other local network doesn't even exist.

Once I deleted the nonexistent nameserver address from my /etc/resolv.conf and had two "good" nameservers at the top of the file, everything started flowing as fast as it should.

Analysis: This problem stems from using DHCP to connect at multiple physical sites, and the slight differences in the DHCP protocol at those various locations is what's making my Web browsing slow down when /etc/resolv.conf is not properly configured for a given location.

The best "solution" is to always connect with a static IP on the router that doesn't transmit new nameserver IPs to my client computer.

In OpenBSD as I have it configured, I do all my network "tweaking" with text files, principally /etc/resolv.conf and /etc/hostname. (in my case /etc/hostname.rl0 /etc/hostname.wi0 and /etc/hostname.rum0 for the three wireless interfaces I have, one wired and two wireless; yes, the BSDs deal with networking a bit differently than Linux, and I've learned a lot by doing all of this manually).

I generally have each "hostname" file filled with a few lines for the various routers I use (with appropriate DHCP or static IP info and any SSID names and WEP or WPA keys needed), and I "pound out" (or "comment out") the lines I don't need. The problem is that I don't keep as close of an eye on /etc/resolv.conf, which is being changed by some of these DHCP servers and not by others.

Without any GUI tools such as the NetworkManager in GNOME, which I've used in Ubuntu and Debian, I either need to be much more mindful of what my configuration files contain at any given time, or I need to write/beg/borrow/steal some shell scripts that allow both the /etc/hostname.X files and /etc/resolv.conf to be modified by me when I decide to connect to one network or another. For instance, I could have the script give me a menu of networks and then modify the configuration files appropriately.

As it is, in Debian and Ubuntu, I often had to go to the NetworkManager to pick a new "location," of which I had many set up just like in this script I envision.

If only there was such a tool already in OpenBSD that would do this for me without needing GNOME, KDE or .... It could already be there and I just don't know about it.

I fondly remember the netconfig script in Slackware, which is one of the simple but supremely useful things I love about that Linux distribution. I'd love something like that in OpenBSD, but hacking into the text files isn't that big of a deal.

And I'll probably avoid the one local network that has DHCP but doesn't send its own nameserver IPs to the client.