[Dnsmasq-discuss] problem with loopback and 2.77test5

Simon Kelley simon at thekelleys.org.uk
Wed May 10 21:48:41 BST 2017

On 10/05/17 14:11, Bastian Bittorf wrote:
> * Simon Kelley <simon at thekelleys.org.uk> [10.05.2017 15:05]:
>> I wonder if this is to do with the extension of the ping-test to more
>> cases. Please could you try adding
>> no-ping
>> to the config, and see if that improves things?
> thank you - yes, that works...now the log shows:
> dnsmasq-dhcp[28815]: DHCPREQUEST(lo) 00:00:00:00:00:00
> dnsmasq-dhcp[28815]: DHCPACK(lo) 00:00:00:00:00:00 lo-alias
> dnsmasq-dhcp[28815]: ARP-cache injection failed: Invalid argument
> could it be, because 'loopback' is not arp-able?

Actually, its the sort-of opposite. loopback seems to respond to any
address in so you get a reply to an ICMP echo request from
any address, even if the loopback interface doesn't
explicitly have that address

srk at holly:~/dnsmasq/dnsmasq$ ifconfig lo
lo        Link encap:Local Loopback
          inet addr:  Mask:
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:2194 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2194 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:164612 (164.6 KB)  TX bytes:164612 (164.6 KB)

srk at holly:~/dnsmasq/dnsmasq$ ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=0.068 ms
64 bytes from icmp_seq=2 ttl=64 time=0.065 ms
--- ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms

I'll patch it to suppress ping-checks for the loopback interface.



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