NetworkManager/SOURCES/70-nm-connectivity.conf

# The Strict mode of RFC3704 Reverse Path filtering breaks some pretty
# common and reasonable use cases.
#
# Notably, it makes it impossible for NetworkManager to do connectivity
# check on a newly arriving default route (it starts with a higher metric
# and is bumped lower if there's connectivity).
#
# Kernel's default is 0 (no filter), systemd configures a Loose filter since
# commit 230450d4e4f1 ('sysctl.d: switch net.ipv4.conf.all.rp_filter from 1
# to 2'). However, RHEL systemd package happens to default to Strict mode
# for historic reasons. Let's override it if we're doing connectivity
# checking.

# Source route verification
net.ipv4.conf.all.rp_filter = 0