Red Hat Bugzilla – Bug 477976
MTU not set correctly for 6to4
Last modified: 2014-03-16 23:16:58 EDT
Created attachment 327863 [details]
Patch for /etc/sysconfig/network-scripts/network-functions-ipv6
Description of problem:
MTU of a 6to4 tunnel setup by /etc/ppp/ip-up.ipv6to4 has an incorrect value. The bug was tracked to a file provided by initscripts for IPv6. (See "Additional info" for discussion.)
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Configure 6to4 to use ppp connection (DSL) from /etc/ppp
2. Run /etc/ppp/ip-up.ipv6to4
3. Observe MTU with "ifconfig tun6to4"
MTU is 1480
MTU should be 1472, which 20 less than the MTU of ppp0
I tracked the bug to /etc/sysconfig/network-scripts/network-functions-ipv6.
The routine ipv6_set_mtu writes the correct value to /proc/sys/net/ipv6/conf/tun6to4/mtu using sysctl, so the MTU is calculated correctly, but set ineffectively.
The corresponding function for IPv4 uses /sbin/ip to set the MTU.
Changing the call to ipv6_exec_sysctl into a call to ipv6_exec_ip (and generally getting rid of all references to /proc in ipv6_set_mtu) produces the expected result and doesn't appear to break anything else, either.
Although this bug is filed against F9, the same bug probably exists in F10, although I haven't checked.
I verified that the bug does exist in F10, as well. I opened Bug 478441 with an F10-appropriate patch file attached.
*** This bug has been marked as a duplicate of bug 478441 ***
initscripts-8.86.1-1 has been submitted as an update for Fedora 10.
initscripts-8.86.2-1 has been submitted as an update for Fedora 10.
initscripts-8.86.3-1 has been pushed to the Fedora 10 stable repository. If problems still persist, please make note of it in this bug report.