DHCP ?


 

JKalchik

TVWBB Guru
<scratches head> I'm wondering if I've fallen into an opportunity. Yes, I've been ears deep in my home network over the last 10 days or so, but everything else seems to be behaving with regards to DHCP. In particular, getting the local domain name assigned as well as an entry in the search order. Odd, with the current HeaterMeter load (LEDE Reboot v15 Release,) my HM is getting assigned an address, but isn't getting the name lookup search, or actually, the configured name server isn't loaded.

/etc/resolv.conf:
search lan
nameserver 127.0.0.1

I'd really like to use symbolic names for fairly obvious reasons. As it stands, all symbolic name lookups are failing. Anything else requesting a DHCP address gets the name server and search entries configured appropriately.

Any suggestions on what I need to look at?
 

DanHoo

TVWBB Wizard
If your nameserver is 127.0.0.1 that's the loop back address of that device.

I'm guessing you'd want that to be something else.
 

Brett-EDH

TVWBB All-Star
Sounds like you’re device isn’t connecting to your network to receive a valid IP address

Most home networks will assign 192.168.x.x as that’s often the LAN default address.

Check to see if your device is actually connected by listing/viewing current connected devices on your router. You can see this in the router admin panel/settings of your router.

If you see your device with an assigned address (per your LAN’s defined address range) then you know the device is on the network.
 

JKalchik

TVWBB Guru
127.0.0.1 is a loop back address. No, my nameserver is not hosted at 127.0.0.1.
It's connecting to the house network just fine, the contents of /etc/resolv.conf were copied directly from an ssh session to it. DHCP also sends the record over to DNS resolver, so I can even refer to it symbolically, i.e. "ssh root@HeaterMeter".

Right now, the only DHCP parameters that don't seem to be used as sent out are the search list, and the name server address. Everything else, including IP address, subnet mask, gateway, time zone, NTP server, all seem to be implemented in the device.
 

JKalchik

TVWBB Guru
Doing a little port sniffing..... I do see all 4 of the DHCP packets headed for the HM (okay, actually to the WiFi access point port.)

Wait a minute.... I may be sunk..... the rPi may not be requesting the parameters that I'm expecting it to use. Looks like I may end up having to hard code the SMTP service address.
 

Bryan Mayland

TVWBB Hall of Fame
The resolv.conf on the HeaterMeter points to the local DNS server on the device (dnsmasq). That has its own resolve.conf file it uses to resolve names in /var/etc/resolv.conf.something. The DNS support on the device I am not sure what the heck happens (despite having a really strong background in networking) because on my HeaterMeter I can't resolve any local addresses even using nslookup, with or without a domain suffix, even supplying the server IP, and I don't even see the query on the DNS server. The HeaterMeter's name resolves from another client on the LAN with or without the suffix. OpenWrt isn't really super-featured when it comes to being a client on a network instead of being a router, in fact it doesn't even supply the hostname when doing DHCP requests, I had to patch that in.

The SMTP service is never going to work, because udhcpc doesn't know anything about how to configure the SMTP client (msmtp). I don't think msmtp will even resolve MX records for the the supplied host.
 

JKalchik

TVWBB Guru
AFAIC, I don't have a strong networking background...... it keeps getting shown to me otherwise. :)

Thanks for the info, Bryan. I think I'm going to move mail from a DHCP address to a fixed address and move on.
 

 

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