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Virtual DNS

A project log for Phone tethering via proxy server

Access the internet without a tethering plan

lion-mclionheadlion mclionhead 11/07/2025 at 08:500 Comments

DNS entailed handling A, AAAA, MX, & PTR requests.  The only real data it returns is the IPv4 address in the A request.  All the other bits are hard coded to dummy values.  The DNS server address is ignored.  It just handles all UDP sent to port 53.  Linux won't forward DNS requests to the phone unless the DNS server is outside the virtual ethernet device so lions simply use the global Comca$t server 75.75.75.75 as a dummy.

root@truckcam:/root% host -v cnn.com
Trying "cnn.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56858
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

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

;; ANSWER SECTION:
cnn.com.                3600    IN      A       151.101.67.5

Received 41 bytes from 75.75.75.75#53 in 89 ms
Trying "cnn.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19994
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;cnn.com.                       IN      AAAA

;; AUTHORITY SECTION:
cnn.com.                3600    IN      SOA     x. x. 4294967295 86400 7200 2419200 3600

Received 63 bytes from 75.75.75.75#53 in 0 ms
Trying "cnn.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49886
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;cnn.com.                       IN      MX

;; ANSWER SECTION:
cnn.com.                3600    IN      MX      10 x.

Received 42 bytes from 75.75.75.75#53 in 9 ms
root@truckcam:/root% host hackaday.com
hackaday.com has address 192.0.66.96
hackaday.com mail is handled by 10 x.


root@truckcam:/root% host cnn.com
cnn.com has address 151.101.67.5
cnn.com mail is handled by 10 x.

root@truckcam:/root% host cnn.com
cnn.com has address 151.101.67.5
cnn.com mail is handled by 10 x.

root@truckcam:/root% ping heroinewarrior.com
PING heroinewarrior.com (216.105.38.10) 56(84) bytes of data.
64 bytes from x (216.105.38.10): icmp_seq=1 ttl=63 time=38.7 ms
64 bytes from x (216.105.38.10): icmp_seq=2 ttl=63 time=248 ms
64 bytes from x (216.105.38.10): icmp_seq=3 ttl=63 time=60.4 ms
64 bytes from x (216.105.38.10): icmp_seq=4 ttl=63 time=86.8 ms
64 bytes from x (216.105.38.10): icmp_seq=5 ttl=63 time=116 ms
64 bytes from x (216.105.38.10): icmp_seq=6 ttl=63 time=206 ms
64 bytes from x (216.105.38.10): icmp_seq=7 ttl=63 time=59.4 ms
^C
--- heroinewarrior.com ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 6003ms
rtt min/avg/max/mdev = 38.713/116.423/247.540/74.151 ms
root@truckcam:/root%


Some programs might malfunction if the reverse DNS name is always x & the authoritative name server is always x.  These bits could always be forwarded to the real DNS, with a lot of effort.  It might need a cache for reverse DNS.

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