[SOLVED] Recent peculiar connectivity behavior

[upnort]

I don't know when this interesting bug appeared. I first noticed the bug about two weeks ago when trying to update a Fedora 21 system to Fedora 22. I can trigger the bug in F22 but not in F21. While I thought the bug was in Fedora, I can trigger the same bug in CentOS 7. My CentOS 7 system is fully updated, running kernel 3.10-229-11.1

Any connectivity change triggers running rc.local. That is, toggling the wireless hardware switch or pulling/inserting the network cable.

I have horrible connectivity if both wired and wireless are enabled. With only one enabled my connectivity is solid.

I do not need to log in. I can boot to a command line, change the cable or wireless switch and watch rc.local stdout appear.

Changing kernels makes no difference. I tried the last five kernels back to 3.10.0.123.20.1. My guess is something new in NetworkManager or systemd. I can stop the new behavior with chmod -x rc.local.

Any ideas where to start debugging?

[AlanBartlett]

Any ideas where to start debugging?

Yes.

Look at what is in your rc.local file, as that is not used in a default CentOS 7 installation.

[Thread moved to CentOS 7 - Networking Support.]

[upnort]

Reducing rc.local to a single echo statement changed nothing. Same results.

By blind guess, disabling sendmail stops the problem. I have not yet found anything on the web to reveal the connection.

[upnort]

I found the problem and solution:

http://forums.fedoraforum.org/showpost. ... ostcount=6

chmod -x /etc/NetworkManager/dispatcher.d/10-sendmail

I have no idea why the problem appears in F22 and CentOS 7 but not in F21. I do not pretend to know the reason for reexecuting rc.local but I am sure the dots connect somehow.