I want to use
dnsmasq when my Mac (Sierra) is not connected to a wifi network.
Configuring DNS servers in the Advanced Network Preferences dialogue box works fine for
nslookup, and I can see via
tcpdump that these tools hit the local
It does not work for
curl and Golang binaries like the Cloud Foundry CLI. These are unable to resolve hosts, and don't attempt to communicate with the local nameserver. When I use
dtruss for the
cf Golang binary, I can see it opening
/etc/hosts. I'm not sure how to spot it attempting to talk to name servers though.
If I stop the
curl take a little longer to fail with
cannot resolve api.local.pcfdev.io: Unknown host, but still fail nonetheless, and without trying to hit the local name server.
Any ideas how on Earth I can get macOS to use my local name server when I'm offline?
I think mDNSResponder - with a running PCF Dev VirtualBox VM but no LAN/WLAN - is missing a default gateway or gets the wrong one. If your interfaces aren't connected or all interfaces are inactive then no default gateway exists.
You can check this with:
netstat -r -f inet Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire 127 localhost UCS 1 0 lo0 localhost localhost UH 5 1380 lo0 192.168.11 link#7 UC 4 0 vboxnet 224.0.0 link#1 UmCS 2 0 lo0 18.104.22.168 link#1 UHmWI 1 0 lo0
To circumvent this you can do the following:
Requirement: a proper configuration of dnsmasq as published in your q & my a. You may have to deactivate all interfaces.
Duplicate a Location profile in System Preferences > Network and rename it to e.g. pcdev with VLAN.
Choose an interface (e.g. Wi-Fi) in the left pane and hit the gear at the bottom of the left pane > Manage Virtual Interfaces. Hit the ⊞-button and add a "New VLAN...". Rename it to VLAN, choose 1 as tag and an interface.
Configure the interface: Manually with an arbitrary but unused IP e.g. 10.228.8.226/Mask 255.255.0.0/Router 10.228.0.1 and DNS-server 127.0.0.1. Apply the settings with the button Apply. IP (+ Mask) and Router have to be in the same network.
Check the routing table again. First it will look like this:
netstat -r -f inet Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire 10.228/16 link#8 UC 2 0 vlan0 127 localhost UCS 1 0 lo0 localhost localhost UH 4 1380 lo0 192.168.11 link#7 UC 2 0 vboxnet 224.0.0 link#1 UmCS 2 0 lo0 22.214.171.124 link#1 UHmWI 1 0 lo0
but after a few seconds (up to 40 seconds in my environment) it should be populated:
netstat -r -f inet Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire default 10.228.0.1 UGSc 3 0 vlan0 10.228/16 link#8 UCS 2 0 vlan0 10.228.0.1/32 link#8 UCS 2 0 vlan0 10.228.0.1 link#8 UHRLWIir 4 0 vlan0 18 10.228.8.226/32 link#8 UCS 2 0 vlan0 10.228.255.255 ff.ff.ff.ff.ff.ff UHLWbI 1 3 vlan0 127 localhost UCS 1 0 lo0 localhost localhost UH 26 1494 lo0 192.168.11 link#7 UC 3 0 vboxnet 192.168.11.11 8:0:27:35:78:e2 UHLWIi 2 3 vboxnet 1192 192.168.11.255 ff:ff:ff:ff:ff:ff UHLWbI 1 3 vboxnet 224.0.0/4 link#8 UmCS 3 0 vlan0 126.96.36.199 1:0:5e:0:0:fb UHmLWI 1 0 vlan0 188.8.131.52 1:0:5e:7f:ff:fa UHmLWI 1 3 vlan0 255.255.255.255/32 link#8 UCS 1 0 vlan0
Now try again to ping api.local.pcfdev.io/tcp.local.pcfdev.io/local.pcfdev.io.
While testing I got the impression that some arbitrary IP pinging (
ping 127.0.0.1 accelerated the reconfiguration).
If you are within reach of a known WLAN switch back to your common Location profile.
This is tested (and working) in a VMwareFusion Sierra VM and the nested pcfdev-ubuntu VirtualBox VM. In this environment I can't really simulate a missing Wi-Fi connection, because there is no Wi-Fi interface available. Instead I deactivated all interfaces (2 x Ethernet) in the Sierra VM.