static routes on CentOS 7 with udev inferface renames

scottmusician · 09-09-2018, 10:01 PM

Hi all,

I am currently studying for my LFCS, and I have a question about static routes.
I've currently been trying to set these up via the 'new file in /etc/sysconfig/network-scripts/route-interface ' method, but the routes don't seem to be taking.

More specifically:
- my udev seems to be pretty overreative, and almost always renames my interfaces (and external disks etc) on reboots - ie. /dev/sdb becomes /dev/sdc, and wlo0 becomes wlo1. I could create a route file called route-wlo0 , but what happens when udev drops this after a reboot because the interface has a new name?

is there another way of specifying the device name?

---

Also, will the route files be read and listed with $ip route ?

Honest Abe · 09-10-2018, 01:04 AM

Hi scottmusician,

Quote:

I've currently been trying to set these up via the 'new file in /etc/sysconfig/network-scripts/route-interface ' method, but the routes don't seem to be taking.

So you add a static route in the file and it doesn't show up in 'ip route show' or 'route -nee' outputs ? Does it remain same for a on-the-fly added dynamic route ? Please show examples of what you are doing and what is expected.

Quote:

- my udev seems to be pretty overreative, and almost always renames my interfaces (and external disks etc) on reboots - ie. /dev/sdb becomes /dev/sdc, and wlo0 becomes wlo1. I could create a route file called route-wlo0 , but what happens when udev drops this after a reboot because the interface has a new name?

Please post the udev rules for the following [Applicable for CentOS 7]

Code:

/usr/lib/udev/rules.d/80-net-name-slot.rules 
/usr/lib/udev/rules.d/71-biosdevname.rules
/usr/lib/udev/rules.d/60-net.rules

And any udev rule you might have created or identified.

To understand the NIC interface naming convention & related troubleshooting - here

scottmusician · 09-10-2018, 01:54 AM

thanks for the reply!

contents of /etc/sysconfig/network-scripts/route-wlo1 (which I created):

Code:

192.168.123.0/24 via 10.4.22.1 dev wlo1

output of #ip route:

Code:

default via 10.4.22.1 dev wlo1 proto static metric 600 
10.4.22.0/19 dev wlo1 proto kernel scope link src 10.4.22.76 metric 600

I can add additional non-persistent routes when using ip route add:

Quote:

#ip route add 192.168.122.0/24 via 10.4.22.1
#ip route
default via 10.4.22.1 dev wlo1 proto static metric 600
10.4.22.0/19 dev wlo1 proto kernel scope link src 10.4.22.76 metric 600
192.168.122.0/24 via 10.4.22.1 dev wlo1

there's just no reporting of the (at least not in $ip route ). I have disabled/re-enabled my network adapter (

Code:

ifdown wlo1 ; ifup *

), and rebooted, but neither have made any difference.

---
output of /usr/lib/udev/rules.d/80-net-name-slot.rules:

Code:

# do not edit this file, it will be overwritten on update

ACTION!="add", GOTO="net_name_slot_end"
SUBSYSTEM!="net", GOTO="net_name_slot_end"
NAME!="", GOTO="net_name_slot_end"

IMPORT{cmdline}="net.ifnames"
ENV{net.ifnames}=="0", GOTO="net_name_slot_end"

NAME=="", ENV{ID_NET_NAME_ONBOARD}!="", NAME="$env{ID_NET_NAME_ONBOARD}"
NAME=="", ENV{ID_NET_NAME_SLOT}!="", NAME="$env{ID_NET_NAME_SLOT}"
NAME=="", ENV{ID_NET_NAME_PATH}!="", NAME="$env{ID_NET_NAME_PATH}"

LABEL="net_name_slot_end"

output of /usr/lib/udev/rules.d/71-biosdevname.rules:

Code:

# do not edit this file, it will be overwritten on update

ACTION!="add", GOTO="net_name_slot_end"
SUBSYSTEM!="net", GOTO="net_name_slot_end"
NAME!="", GOTO="net_name_slot_end"

IMPORT{cmdline}="net.ifnames"
ENV{net.ifnames}=="0", GOTO="net_name_slot_end"

NAME=="", ENV{ID_NET_NAME_ONBOARD}!="", NAME="$env{ID_NET_NAME_ONBOARD}"
NAME=="", ENV{ID_NET_NAME_SLOT}!="", NAME="$env{ID_NET_NAME_SLOT}"
NAME=="", ENV{ID_NET_NAME_PATH}!="", NAME="$env{ID_NET_NAME_PATH}"

LABEL="net_name_slot_end"
[root@centosia network-scripts]# cat /usr/lib/udev/rules.d/71-biosdevname.rules
SUBSYSTEM!="net", GOTO="netdevicename_end"
ACTION!="add",    GOTO="netdevicename_end"
NAME=="?*",       GOTO="netdevicename_end"
ATTR{type}!="1",  GOTO="netdevicename_end"
ENV{DEVTYPE}=="?*", GOTO="netdevicename_end"

# whitelist all Dell systems
ATTR{[dmi/id]sys_vendor}=="Dell*", ENV{UDEV_BIOSDEVNAME}="1"

# kernel command line "biosdevname={0|1}" can turn off/on biosdevname
IMPORT{cmdline}="biosdevname"
ENV{biosdevname}=="?*", ENV{UDEV_BIOSDEVNAME}="$env{biosdevname}"
# ENV{UDEV_BIOSDEVNAME} can be used for blacklist/whitelist
# but will be overwritten by the kernel command line argument
ENV{UDEV_BIOSDEVNAME}=="0", GOTO="netdevicename_end"
ENV{UDEV_BIOSDEVNAME}=="1", GOTO="netdevicename_start"

# off by default
GOTO="netdevicename_end"

LABEL="netdevicename_start"

# using NAME= instead of setting INTERFACE_NAME, so that persistent
# names aren't generated for these devices, they are "named" on each boot.
SUBSYSTEMS=="pci", PROGRAM="/sbin/biosdevname --smbios 2.6 --nopirq --policy physical -i %k", NAME="%c"  OPTIONS+="string_escape=replace"

LABEL="netdevicename_end"
[root@centosia network-scripts]# 
[root@centosia network-scripts]# cat /usr/lib/udev/rules.d/71-biosdevname.rules
SUBSYSTEM!="net", GOTO="netdevicename_end"
ACTION!="add",    GOTO="netdevicename_end"
NAME=="?*",       GOTO="netdevicename_end"
ATTR{type}!="1",  GOTO="netdevicename_end"
ENV{DEVTYPE}=="?*", GOTO="netdevicename_end"

# whitelist all Dell systems
ATTR{[dmi/id]sys_vendor}=="Dell*", ENV{UDEV_BIOSDEVNAME}="1"

# kernel command line "biosdevname={0|1}" can turn off/on biosdevname
IMPORT{cmdline}="biosdevname"
ENV{biosdevname}=="?*", ENV{UDEV_BIOSDEVNAME}="$env{biosdevname}"
# ENV{UDEV_BIOSDEVNAME} can be used for blacklist/whitelist
# but will be overwritten by the kernel command line argument
ENV{UDEV_BIOSDEVNAME}=="0", GOTO="netdevicename_end"
ENV{UDEV_BIOSDEVNAME}=="1", GOTO="netdevicename_start"

# off by default
GOTO="netdevicename_end"

LABEL="netdevicename_start"

# using NAME= instead of setting INTERFACE_NAME, so that persistent
# names aren't generated for these devices, they are "named" on each boot.
SUBSYSTEMS=="pci", PROGRAM="/sbin/biosdevname --smbios 2.6 --nopirq --policy physical -i %k", NAME="%c"  OPTIONS+="string_escape=replace"

LABEL="netdevicename_end"

output of /usr/lib/udev/rules.d/60-net.rules:

Code:

ACTION=="add", SUBSYSTEM=="net", DRIVERS=="?*", ATTR{type}=="1", PROGRAM="/lib/udev/rename_device", RESULT=="?*", NAME="$result"

Hope that makes sense!

Honest Abe · 09-10-2018, 03:03 AM

Code:

# using NAME= instead of setting INTERFACE_NAME, so that persistent
# names aren't generated for these devices, they are "named" on each boot.
SUBSYSTEMS=="pci", PROGRAM="/sbin/biosdevname --smbios 2.6 --nopirq --policy physical -i %k", NAME="%c"  OPTIONS+="string_escape=replace"

Looks suspicious..

So please follow this to resolve.

A simpler example is here, if you are unsure on how to pass arguments at boot time.

scottmusician · 09-10-2018, 07:31 AM

so that might solve the device rename issue

but shouldn't I be able to see the route-wlo1 file's contents in the output listed from $ip route?

Honest Abe · 09-11-2018, 04:35 AM

yes, baby steps

Once the device rename stops, static route should work with route-NIC files.

Also, the steps you are taking (create file -> add route -> ifdown/ifup NICs) are what we used to do with network services. CentOS7 uses NetworkManager, so please try nmcli con down /nmcli con up for your connection too.

I'll admit that I still use ifdown-ifup and never saw this, but just ticking all boxes.