Local DNS

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Using ASUSWRT for Local DNS and DHCP

Posted by Ripdubski on 2015.05.26
Posted in: Router. Tagged: , , , , , , . 5 Comments

A little background on ASUSWRT.  ASUSWRT is the firmware ASUS ships on current routers.  It started as a fork of the Tomato firmware project.  Tomato is similar to DD-WRT.  ASUSWRT-Merlin is an enhanced, and fixed (some), version of the ASUS supplied ASUSWRT.

 

Post Switch Concerns

After switching to ASUSWRT from DD-WRT I thought I would be losing the ability to serve local DNS.    I was wrong.  I loaded ASUSWRT-Merlin on my ASUS RT-N66U.  After some trial and error configuration I discovered local DNS is alive and well in ASUSWRT-Merlin.

There is one minor caveat in that local DNS only works for DHCP served addresses, unless you further modify the dnsmasq configuration from the command line.  I spent a lot of time managing non-DHCP addresses in that fashion with DD-WRT, and want to make management as simple as possible.  The dnsmasq service used by ASUSWRT operates as a masquerading forwarding DNS server.

With DD-WRT I had non-DHCP addresses allocated in a certain range (0-99), and DHCP addresses from 100 to 255.  Within the DHCP addresses I reserved the first 20 (via DHCP reservations) for our devices.  Which let any guests pickup other addresses.  Why?

With DD-WRT I broke the DHCP range into two and had QOS rules in place for each group.  Guest addresses received tighter restrictions and lower bandwidth.   Managing these in DD-WRT was a pain. The ASUSWRT makes it a lot simpler to accomplish the same things.

 

Local DNS Setup

I couldn’t find any definitive guides on setting this up, only that it could be done.  So heres how.  Before proceeding, to make things easier, make sure all devices in the ASUS Client list have a name showing up.  If the name doesn’t show up, click it’s MAC address  (top one) and define it in the pop-up window that appears.

Open the LAN menu, and “DHCP Server” tab.  A few things to note:

a) “Enable the DHCP Server” should be Yes.

b) The routers Domain Name can be blank or you can set it to what you want, just don’t use one of the top level domains like com, net, org, etc.  I chose “home”.  This makes all hosts on my network resolvable as “hostname.home”.

c) Set the DHCP starting and ending range, for example 192.168.1.10 to 192.168.1.150.  The subnet and final address are blocked out in the image.  For the subnet, it should be the same as the routers defined subnet.  If you defined the routers address as 192.168.1.1 then the IP range should be on subnet 1.  I don’t use 1.

d) The “Default Gateway” is the gateway that clients will route through.

e) Now the DNS settings need special attention:

If you select Yes for “Advertise routers IP in addition to user specified DNS”, then the routers address will be appended to the DNS address list given to the clients when they lease an IP address.  I said “appended” meaning it will be LAST!

So if you want to be able to resolve names on your network without specifying the routers address as the name server to do the resolution (i.e.: nslookup – 192.168.1.1), then you should make sure the Advertise setting is set to No, and put the routers address in “DNS Server 1”.  This puts the router in the list FIRST!  Apply your secondary (if any) in “DNS Server 2”.

The last thing surrounding DNS, which ties into the router domain defined above, is the “Forward local domain queries to upstream DNS”.  This should be No.  You don’t want a query for “xbox.home” to be passed up to be resolved at the internet level.  You want it to stay on your network.

With DNS setup in this way, your hosts (blah.home) are answered first from the local DNS cache while external hosts (www.apple.com) are answered from your ISP (or OpenDNS, Google, etc) DNS servers.

 

ASUSWRT-LocalDNS

f) Click the Apply button when done.

DHCP

I typically assign a static address to devices that I want to always be at a certain address (like a printer, NAS drive, etc).  I typically setup appliances like streaming players and TV’s with static addresses too since they really don’t need to change.

I still wanted to resolve the problem where these non-DCHP devices (devices with static IP assignments) could be resolved on the network WITHOUT having to modify configuration from the command line.  Remember, simple, low maintenance.

To resolve this I changed all devices with static IP’s to DHCP.  Bonus that makes device setup simpler too.  I then setup DHCP reservations for them within the DHCP pool in a particular range (99 or less). This way I can easily identify “appliances” from computing devices.

a) Set the “Enable Manual Assignment” to Yes.

b) Use the dropdown to select a device, which will have the MAC address or device name (if it was given by the requesting client or defined manually on the ASUSWRT Client list).

 

c) Set the address (it will default to whatever it was assigned by the server).  If you want to change it, change it.

d) Click the + button.

e) Click the Apply button.

ASUSWRT-DHCPStatic

Traffic Control

With DD-WRT I had devices setup in ranges with guest range relegated to low bandwidth and peer to peer services blocked.  I want the same thing with ASUSWRT.  I also had my devices defined with particular classes of service.

The ASUSWRT firmware has defaults based on traffic type, mainly surrounding file transfer.

Once enabled you can delete the default ones, and add custom ones.

I added the peer to peer services using the service name drop down and selecting the common ones.  To add, select it, set the priority, and click the + sign icon.

I then added my devices, this time using the Source IP or Mac dropdown.  The name will show up if it was offered by the requesting client or was manually defined on the ASUS Client list.  This makes it a cinch to add, unlike DD-WRT where you add each device by MAC address only.

ASUSWRT-TrafficPriority

Once defined, click the Apply button.

So what about the lower priority guest traffic?  With ASUSWRT, any traffic not matching a rule gets routed to the “Low” setting.  I have my low and lowest settings set to use very little bandwidth.

I now have ASUSWRT doing everything DD-WRT was doing, and without command line management.

 

Oh, and now is a good time to backup the configuration using the Administration/Save feature.

 

DD-WRT Web Server for Viewing All Network IPs

Posted by Ripdubski on 2014.04.14
Posted in: DD-WRT. Tagged: , , , , , , , , , . Leave a comment

dd-wrtNOTE: I no longer use DD-WRT and am unable to answer any questions about it.

Expanding on my last post of setting up a static page, this post will create dynamic content (albeit at boot time) to be served statically using the embedded HTTP server in DD-WRT.

For small home networks with a mix of leased and non-leased IP addresses, it is sometimes useful to see all of the allocated addresses at one time.  Or maybe you can’t remember the name of a device in which name lookup does you no good.  You can use this method to create a static web page that has both hosts you define with static addresses, and hosts with dynamic addresses assigned by the DD-WRT DHCP server.  Of the latter, it will include DHCP addresses that have reservations.

Why separate the static addresses from the reserved DHCP addresses?

  • I assign hardware devices like printers, set top boxes, and game consoles with static addresses.  Set and forget, almost.  I use a range of address outside of the DHCP pool for this purpose and I keep track of it on a spreadsheet.  These devices should never have to change, ever, so I don’t need them managed by DHCP.
  • I have two ranges with a single DHCP pool for two different purposes.  The first is the equipment in our family; laptops, phones, etc.  I want these in the first range.  I want them to grab DNS and gateway information from the router as well as their address so I don’t have to maintain them at each device, but I also want them to have the same IP at each boot, so I set them up with reservations in DHCP (within the first range).  The second range is for guest equipment (visitors phones, etc).  I apply two different QOS (quality of service) settings to these ranges.  If you’re a guest, you get no P2P and your traffic has the lowest priority on my network.  Sorry.

 

End Result

What you’ll end up with is a web page that has two panes.  One pane shows all the static addresses you create, the other pane shows all the DHCP leases (at router boot time).  You will access it by entering the following URL into your device’s browser: “http://router_address/user/hosts.html”.  If you have setup the router so that DNSmasq resolves local DNS names, you can substitute the router address for its name on the network – I covered that in an earlier post here.  This is what the web page will look like when complete:

HostsPage

It’s simple, small, and fast.  You can customize the headers, footers, and titles to be as pleasing as you want.  Keep in mind the HTTP server doesn’t have all the bells and whistles you would normally have.

 

Setup, File Creation

First you need to create a hosts file containing the entries for the statically assigned (not reserved DHCP).  These are the printers, set top boxes, game consoles, etc.  Devices that don’t leave the house and have no reason to ever change.

  • Login to the router as the administrator.
  • Change directory to /jffs/www: “cd /jffs/www”
  • Create the hosts file with vi: “vi hosts”.  The syntax is IP address, tab, device name, device name alias.  The content will be similar to this:

192.168.56.20 dsnas nas
192.168.56.40 wii
192.168.56.41 xbox
192.168.56.60 zinohd bluray dvd
192.168.56.70 mg6120 printer

  •  Create the file that will be served by the HTTP server (hosts.html).  This will use a frame set, yes I know it can be done with CSS but I was keeping this pure HTML.  Still in the “/jffs/www” directory, using vi: “vi hosts.html”:

<!--DOCTYPE html>
<html>
<frameset cols="50%,50%">
<frame src="hoststat.html" />
<frame src="hostdhcp.html" />
</frameset>
</html>

  • Create a header stub file (“hosts_head.html”) which will be used in the dynamic creation of the pages contents.  In the same directory “/jffs/www”, again using vi: “vi hosts_head.html”:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html" />
<title>DNS Hosts - home</title>
</head>
<body>

  • Create a footer stub file (“hosts_foot.html”) which will be used in the dynamic creation of the pages contents.  In the same directory “/jffs/www”, again using vi: “vi hosts_foot.html”:

</code>
</body>
</html>

  • Create the Static pane’s title file (“hosts_title_stat.html”).  In the same directory “/jffs/www”, again using vi: “vi hosts_title_stat.html”:

<h3>DNS Hosts (Static) - home</h3>
<code>

  • Create the DHCP (leased) pane’s title file (“hosts_title_dhcp.html”).  In the same directory “/jffs/www”, again using vi: “vi hosts_title_dhcp.html”:

<h3>DNS Hosts (Leased) - home</h3>
<code>

 

Setup, Activation

  • Now the router has to be told to create the pages at boot. You will utilize the boot script to do it. If you already have one, append this to it. If you don’t have one, create it.  In the directory “/jffs/bin”, again using vi: “vi boot_set.sh”:

# Setup DNS Host web page
# Copy the hosts.html file from /jffs/www to the serving location /tmp/www
cp /jffs/www/hosts.html /tmp/www/hosts.html
# Setup DNS Static web page frame
# Copy the header to a new file in /tmp/www as hoststat.html.
cp /jffs/www/hosts_head.html /tmp/www/hoststat.html
# Concatenate the title stub onto the new file.
cat /jffs/www/hosts_title_stat.html >> /tmp/www/hoststat.html
# Parse the contents of the hosts file you created above into the new file.
while read line; do
echo "${line}
" >> /tmp/www/hoststat.html
done < /jffs/etc/hosts
# Concatenate the footer stub onto the new file
cat /jffs/www/hosts_foot.html >> /tmp/www/hoststat.html
# Setup DNS Leased web page frame
# Copy the header to a new file in /tmp/www as hostdhcp.html.
cp /jffs/www/hosts_head.html /tmp/www/hostdhcp.html
# Concatenate the title stub onto the new file.
cat /jffs/www/hosts_title_dhcp.html >> /tmp/www/hostdhcp.html
# Parse the contents of the hosts file generated by DNSmasq into the new file.
while read line; do
echo "${line}
" >> /tmp/www/hostdhcp.html
done < /tmp/hosts
# Concatenate the footer stub onto the new file
cat /jffs/www/hosts_foot.html >> /tmp/www/hostdhcp.html

  • If you have just created the boot script, you need to tell DD-WRT to use it. I showed you how in a previous post here.
  • Reboot the router so it will go through the file generation steps.

 

That’s all there is to it. Enjoy!

Using DD-WRT for Local DNS and DHCP

Posted by Ripdubski on 2013.03.26
Posted in: DD-WRT. Tagged: , , , , . 24 Comments
English: Screenshot of DD-WRT v24 SP2 mini bui...

English: Screenshot of DD-WRT v24 SP2 mini build running on a Linksys WRT160N. MAC address and WAN IP blanked out. (Photo credit: Wikipedia)

NOTE: I no longer use DD-WRT and am unable to answer any questions about it.

I’ve been slowly feeding you information on how to get the most out of the open-source DD-WRT router firmware.

In this article I’ll show you how to setup DD-WRT to act as a local name server on your home network and as a forwarder for external requests.  This will let you lookup names on your internal network (like xbox360, bluray, printer, etc) and continue to lookup names for external sites (like http://www.bing.com, http://www.opendns.com, http://www.apple.com, etc).

Before you begin you should have already enabled JFFS.  I showed you how here: Enable JFFS on DD-WRT

Enable DNS and DHCP

First you need to enable Local DNS and DHCP.  This turns on DNSMasq (built into DD-WRT) to do local network name resolution and distribute IP addresses via DHCP.  Pooled addresses get used and released via timed leases (devices using a pooled address may not always get the same IP address).  Static Addresses entered in the DHCP options are respected by DNSMasq and issued to the devices when they connect and request an IP address (devices using static addresses always get the same IP address).  Use a static address for devices that will never need to change, like your printer or a desktop computer.

  • Open a browser and point it to your router running DD-WRT.  Authenticate with the admin ID and password when needed.
  • Go to the “Setup > Basic Setup” tab.
  • In the “Network Setup > Router IP” section, enter the following details:
Local DNS = 0.0.0.0
  • In the “Setup > Basic” tab, in the “Network Address Server Settings (DHCP)” section, set the following options:
DHCP Type = DHCP Server
DHCP Server = Enable
Start IP Address = Whatever you want
Maximum DHCP Users = However big a pool you want. Do not overrun subnet!
Client Lease Time = 1440
Static DNS Addresses: 192.168.64.1, 208.67.220.220, 208.67.222.123
WINS = 0.0.0.0
Use DNSMasq for DHCP = Enable
Use DNSMasq for DNS = Enable
DHCP Authoritative = Enable

Note:  The Static DNS Addresses will be different for your network.  In this case I have set the address of the router itself (192.168.64.1) – fill in your routers address here (not the WAN one), and two OpenDNS name servers (208.67.220.220 and 208.67.222.123).  I’ll talk about OpenDNS in another post, but what these do is filter websites based on my custom criteria (*.220.220).  In the event that server does not respond in a timely manner, the request then goes to a more restrictive pre-configured filter supplied by OpenDNS FamilyShield (*.222.123).  The filtering effectively blocks access to sites deemed inappropriate.

  • In the “Services Management > DHCP Server” section, set the following options.  In this example I use “home.net” as the home network identifier.   You can replace “home” with whatever your like.  You can replace “.net” with a few different choices.  Home networks are most closely categorized into “.net” or “.info”.  If you are not registering a domain name to point to your WAN IP address, you can use whatever you want including “.com” or “.mil”.  You can, but don’t – home networks are not commercial or military.  Further, don’t use “.example”, “.test”, “.invalid”, or “.localhost” – these are reserved.  See the following link for a list you can choose from: top level domains.
Used Domain: LAN & WLAN
LAN Domain: home
Add any static leases you want or need.
  • In the “Services Management > DNSMasq” section, set the following options:
DNSMasq = Enable
Local DNS = Enable
  • There is a field for “Addition DNSMasq Options” in the DNSMasq section.  Set it as follows:
local=/home/
expand-hosts
domain-needed
bogus-priv
addn-hosts=/jffs/etc/hosts.home
strict-order

You may find these options useful as well:
no-poll : (may be useful to reduce system load on non embedded as well)
no-hosts : (we’re not going to read from any system generated hosts file on a ram disk) (for this configuration DO NOT set this!)

  • Click “Apply Settings”, then “Save”.

Create Static Hosts File

Now you need to create a hosts file that will be persistent across reboots for those devices which are you want using static IP addresses (like printers, routers, etc).

  • ssh into the router and login as root.
  • Change directory to jffs/etc: “cd /jffs/etc”
  • Create and edit the file “hosts.home” using vi (vi hosts.home).
  • Add the entries and save the file (with “ESC Z Z” or “:w!:q!”.  Entry formats are “xxx.xxx.xxx.xxx name” where xxx.xxx.xxx.xxx is the IP address you want to reserve and name is the device name you want referenced as.  Multiple names can be given, just enter them all on the same line separated by a space (xxx.xxx.xxx.xxx name1 name2 etc).

Reboot

Reboot the router by going to the “Administration > Management” tab in the browser interface.  Scroll to the bottom and click the “Reboot Router” button.

If all goes well, you should be able to lookup names on your network like “xbox360” or “xbox360.home” and get a result, as well as normal internet name resolution for external sites like “www.apple.com”.

If you can not resolve local names, you may need to release and re-acquire the IP and DNS information on the host your trying to resolve from.  The easiest way is to just reboot it as well.

Note: Netflix on iOS devices causes DNSMasq to think a DNS rebind attack is occurring and by default an option in DNSMasq is forcibly set that you can not override in the GUI. A special workaround is needed to remove that option when DNSMasq starts.  I showed you how to fix rebind here: Fixing DNS Rebind on DD-WRT