Blackhole route


I've just built an image of the master trunk for my Asus RT-N16, as I did tens of times before.

But this time, I decided to include the ROOter package to test an LTE modem that I just got. I wonder this is the reason of my problem.

So, what it is about is that I'm getting this blackhole looping route that doesn't let any traffic go out:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         hopenwrt.lan         UG    0      0        0 lo
default         UG    1      0        0 eth0.1     *        U     1      0        0 eth0.1     *        U     5      0        0 br-lan

If I delete the first route, everything is working again, but where is it coming from? Lede or Rooter?

Of course I can try to build an image without Rooter but going through all the configurantion again is a lot of time. So, does anyone have an hunch to help me? I wouldn't like to resort to the brute force of placing a route del at rc.local.


Why don't you use standard OpenWRT and install the package?

If you're asking if there's a blackhole route installed in default OpenWRT, the answer is no.

Thank you for helping.

Why don’t you use standard OpenWRT and install the package?

Simply because this router has many, many, packages that wouldn't fit installed, it must be built in the image. Not to mention the trouble of installing the whole chunk everytime an upgrade is done

Just FYI, it has asterisk, openvpn, vsftp, it's a workhorse. Only asterisk deals with more than a hundred calls a day.

So, in your opinion, there's no setting in Openwrt that could cause that default route, as I understood. Well, to prove it, I'll have to build an image without Rooter and check.

Thank you again,

Why do you have to build an image just to check????

I just told you that OpenWRT does not create a blackhole route by default...and there's a pre-built firmware for your device already.

You could be compiling a bad config into your firmware...using the firmware on the OpenWRT site to test would check for that as well.

I think I don't have to waste that time because the image I had working before, without Rooter, was a snapshot about one month old and didn't have this problem.

But, one month has past and ***** happens, sorry, bugs happen, you know, sometimes in much less than a month, at least in my own code. So, I'll better test against the current snapshot.

Thanks again.

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I definitely understand the challenges of packing everything into 16 MB of flash. Downloading the "Image Builder" might be a good intermediate step as it should have been built with "default" config, both for your device as well as the packages.

./scripts/ will also show what's "different" in your top-level config from "stock".

Thank you for replying.

Actually it's more the trouble of installing everything each time because my RTN-16 has 32MB of flash. So, first reason is not space. Also, I have the whole toolchain in my Gentoo system, and it doesn't bother me to take half an hour to build it.

Anyway, I thought I would just ask this before going into more wasted, or spent, time because I thought most of you would know the answer without thinking much. For me, I'm a bit out of my league.

Thank you again.

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Just for the record of future viewers, I took out ROOter and built the same snapshot, although applying the backup configuration I had before ROOter and the Blackhole route is gone:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         a79-168-87-254.         UG    20     0        0 eth0.2        *      UH    0      0        0 tun0     *        U     20     0        0 eth0.2     *        U     10     0        0 br-lan

I wanted ROOter, most of all, because it would give me fast and precious indications of the modem status, namely signal strenght and signal-to-noise ratio. I don't need it to get the modem connected because, after all, it only takes one line of script.

Well, I guess I'll have to live without it because I don't have the time to go through the ROOter scripts.

By the way, thank you all that have been contributing to OpenWrt and enabled me to use this wonderful tool for, I don't know, maybe a decade?

[EDIT] A few days after, as I badly wanted ROOter, I discovered that it was the culprit but through mwan3 which was teaking the routing table. Took out mwan3 and ROOter is giving me all I want, which is modem connection at twice the speed of native OpenWrt NCM protocol, status and supervision.

Keep well,