The DHCP client, dhclient, in 11.2 was changed to support server-side MTU ( https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206721 ), but this MTU feature being enabled by default causes an unexpected change in behavior on upgrade, which to me is a POLA violation.
My ISP sends a bogus MTU of 576, and I've seen reports of others that do the same. Previously this was ignored since the client didn't support processing the MTU, but now it's respected and breaks connectivity since the MTU should really be 1500.
There doesn't appear to be any way to override the client behavior either. Using a request line that doesn't include interface-mtu doesn't help since if the server always sends it, it is still read and respected. Any supersede value in dhclient.conf appears to be ignored in favor of the server-supplied value.
The link bounces when the MTU is set as well, at least on e1000. I see dhclient was changed to help cope with that but it also affects other things that key off link up/down events and can lead to a loop depending on what those scripts do.
Can this feature be changed so that it's optional and disabled by default? Either a command-line option or a dhclient.conf directive would work. As-is, it's making the stock dhclient unusable here without patching out that feature. I can see people wanting to use that, but it shouldn't be on for everyone out of the box.
Jim P. _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
