[FS#781] nslookup - cant optionally use a specified DNS server

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - FreifunkUFO (FreifunkUFO) 

Attached to Project - LEDE Project
Summary - nslookup - cant optionally use a specified DNS server
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - lede-17.01
Due in Version - Undecided
Due Date - Undecided
Details - the optional dns-server parameter for nslookup doesnt work.

the system only makes a reverse-lookup for that dns-server-adress (to the server mentioned in /etc/resolv.conf) and then makes the dns query to the same server (mentioned in /etc/resolv.conf)

my reproducable test (freifunk-firmware, with lede 17.01.0 on nanostation m5):
device 10.61.211.54: i changed /etc/resolv.conf to server 10.61.71.52
device 10.61.211.53: tcpdump the nodes traffic
device 10.61.71.52: dns-server mentioned in /etc/resolv.conf of first device

---
root at 211-54:~# nslookup
BusyBox v1.25.1 () multi-call binary.

Usage: nslookup [HOST] [SERVER]

Query the nameserver for the IP address of the given HOST
optionally using a specified DNS server



root at 211-54:~# nslookup freifunk.net 10.61.72.45
Server:    10.61.72.45
Address 1: 10.61.72.45

nslookup: can't resolve 'freifunk.net': Try again


---




21:35:49.136570 IP (tos 0x0, ttl 64, id 52659, offset 0, flags [DF], proto UDP (17), length 70)
    mid2.211-54.olsr.leipzig.freifunk.net.37064 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 3998+ PTR? 45.72.61.10.in-addr.arpa. (42)
21:35:51.637006 IP (tos 0x0, ttl 64, id 52893, offset 0, flags [DF], proto UDP (17), length 70)
    mid2.211-54.olsr.leipzig.freifunk.net.37064 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 3998+ PTR? 45.72.61.10.in-addr.arpa. (42)
21:35:54.140237 IP (tos 0x0, ttl 64, id 53000, offset 0, flags [DF], proto UDP (17), length 58)
    mid2.211-54.olsr.leipzig.freifunk.net.59626 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 48702+ A? freifunk.net. (30)
21:35:54.140893 IP (tos 0x0, ttl 64, id 53001, offset 0, flags [DF], proto UDP (17), length 58)
    mid2.211-54.olsr.leipzig.freifunk.net.59626 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 53547+ AAAA? freifunk.net. (30)
21:35:56.643070 IP (tos 0x0, ttl 64, id 53236, offset 0, flags [DF], proto UDP (17), length 58)
    mid2.211-54.olsr.leipzig.freifunk.net.59626 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 48702+ A? freifunk.net. (30)
21:35:56.643599 IP (tos 0x0, ttl 64, id 53237, offset 0, flags [DF], proto UDP (17), length 58)
    mid2.211-54.olsr.leipzig.freifunk.net.59626 > 71-52.olsr.leipzig.freifunk.net.53: [udp sum ok] 53547+ AAAA? freifunk.net. (30)




More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=781