Red Hat Bugzilla – Bug 71505
configuring rp_filter for an interface that is added after boot
Last modified: 2014-03-16 22:30:01 EDT
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Description of problem:
/proc/sys/net/ipv4/conf/eth0/rp_filter controls the (poorly documented) reverse
path filter feature for eth0. The user can control this through
/etc/sysctl.conf, but sysctl(8) is only run automatically at boot time. Since
interfaces are brought up at other times, the right control would be a new
variable within /etc/sysctl/network-scripts/ifcfg-*. ifup should implement this.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
On a notebook with eth0 on a PCMCIA card
On a notebook where eth0 is a PCMCIA card:
1.in /etc/sysctl.conf, place "net.ipv4.conf.eth0.rp_filter = 0"
but leave net.ipv4.conf.default.rp_filter = 1
4.examine /proc/sys/net/ipv4/conf/eth0/rp_filter. It will be 1 but should be 0.
Actual Results: /proc/sys/net/ipv4/conf/eth0/rp_filter is 1
Expected Results: /proc/sys/net/ipv4/conf/eth0/rp_filter is 0
rp_filter should be better documented. It does not seem to be mentioned in the
man pages. It is described in the kernel source files:
Closing bugs on older, no longer supported, releases. Apologies for any lack of
Realistically, the best way to support this is probably via a udev rule on
device creation in current releases.