[lug] Fedora 19 Network Config Q

stimits at comcast.net stimits at comcast.net
Fri Nov 22 20:56:45 MST 2013


Just a quick not on actual hardware before I show something that was 
really odd, probably caused by saving a configuration at the moment 
comcast decided to do an unannounced firmware update while I was in the middle of reconfiguring unrelated NICs. All NICs had mysteriously stopped working...

machine has run quite a while with only the built in em1, running DHCP 
to a cable modem in bridging mode (only real world IP address). 
Distribution was fedora 16. I recently just added fedora 19 which has 
been very close to everything I need (I still have the f 16 install). 
DHCP was great. Now I need a private 192.168.x.x setup, and additionally
 a bridge. I've installed a PCI NIC, which has functioned great for a 
few days on the 192.168.x.x. I also installed a dual port PCIe x1 NIC 
which was inexpensive and shows support for linux on a realtek 
chipset...this worked great in windows, but can't be seen or found in 
linux. Even after installing the linux kernel driver from the 
manufacturer's site. So I've been ignoring it for a few days, as I don't
 need the bridge quite yet, and having it function as a regular NIC in 
windows tells me it isn't broken. After a few days, I start to 
investigate why this NIC does not show up with ifconfig -a nor even on 
lspci. I know that the network p2p1 applies to the PCI NIC that was working 
on my 192.168.x.x subnet.

So, I'm in the middle of looking at 
things, and trying to save a test configuration, one not involving em1 
nor p2p1. Comcast drops out with a firmware update to their cable modem.
 Things stop working in all ways, even em1. Now I come back, I'm finding
 that there are files in /etc/sysconfig/networking/ and 
/etc/sysconfig/network-scripts/ which are seemingly shadows of each 
other. It gets weird because it turns out that file ifcfg-em1 is only in
 ...networking/, and not in ...network-scripts/. My old f 16 install has
 no scripts with "Wiredconnection" names, but does have a 
network-scripts/ifcfg-em1. The new f 19 install now has no 
network-scripts/ifcfg-em1, but does have ifcfg-Wiredconnection_1 and 
ifcfg-Wiredconnection_2 in multiple locations. Turns out that the MAC 
address in _1 and _2 of the network-scripts are SWAPPED in the 
networking subdir _1 and _2...their idea of MAC address reverses between these 
two files. Then it gets even more odd...these files have multiple HARD 
links; I tried to temporarily deactivate one to see what happens on 
bringing up an interface, and it refuses to bzip2 because there are 
multiple hard links. ifcfg-Wiredconnection_1 in one directory is HARD 
linked to ifcfg-Wiredconnection_2 in another directory!

So after 
copying the network-scripts version of Wired 1 and 2, I forcibly removed
 the files. I copied over my fedora 16 network-scripts/ifcfg-em1, but 
deleted the UUID. em1 now works. Still working on p2p1, as I can bring 
it up and drop it, or ifconfig the 192.168.x.x address, and it only 
appears to work...the actual communication to the network is missing. 
Perhaps firewall? Perhaps some other setting? Another swap of hardware 
descriptions? Don't know yet.

So what is the difference in 
purpose between /etc/sysconfig/networking/ and 
/etc/sysconfig/network-scripts/ ? They seem to exist because of multiple
 software packages. /etc/sysconfig/ is provided by rpm "filesystem", the
 networking subdir is provided by "system-config-networking", and the 
network-scripts subdir is provided by "initscripts". Could these 
packages have intentionally created multiple hard links to the same 
file? This seems like a really really bad idea.

A related 
question to these different subdirectories, how is the UUID used? Is 
this used in firewall setup? Is this generated from something other than
 MAC address?

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