app-virtualdns

Prerequisites

Allow Node to bind to port 53 without sudo

In UNIX-like systems, non-root users are unable to bind to ports lower than 1024. This is a nuisance when proxying adresses on port 80. Tipically, you end up sudoing all apps that must bind to such ports. However, since kernel 2.6.24, you can use the setcap command to set specific capabilities to a program. To enable all node programs to bind on any port lower than 1024, issue the following command:

$ sudo apt-get install -y libcap2-bin
$ sudo setcap 'cap_net_bind_service=+ep' $(readlink -f $(which node))

Command $(readlink -f $(which node)) usually returns /usr/bin/nodejs.

Usage

After service running, try to resolve the domains using the following command:

$ dig @127.0.0.1 demo.devebot.com

The result may be similar to below output:

; <<>> DiG 9.9.5-3ubuntu0.8-Ubuntu <<>> @127.0.0.1 demo.devebot.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24815
;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;demo.devebot.com.			IN	A

;; ANSWER SECTION:
demo.devebot.com.		1800	IN	A	127.0.0.127

;; Query time: 2 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Sep 15 16:28:08 ICT 2016
;; MSG SIZE  rcvd: 48

Try the forwarder (8.8.8.8) running:

$ dig @127.0.0.1 devebot.com

The output will be:

; <<>> DiG 9.9.5-3ubuntu0.8-Ubuntu <<>> @127.0.0.1 devebot.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 64979
;; flags: qr rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;devebot.com.			IN	A

;; ANSWER SECTION:
devebot.com.		299	IN	A	192.30.252.154
devebot.com.		299	IN	A	104.27.132.59
devebot.com.		299	IN	A	104.27.133.59

;; Query time: 88 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 16 10:39:04 ICT 2016
;; MSG SIZE  rcvd: 77