Re: experimental support for IPv4 unicast extensions
> I have been corresponding with the authors of Internet-Drafts that relax > restrictions on parts of the IPv4 address space to allow normal unicast > use, and I have FreeBSD changes to allow experimentation with these > updates. This message summarizes my changes, and solicits input. > > The changes are all controlled by sysctl, and default to "off". > The parts of the address space in question and the relevant changes: > > 0/8 (network 0) [1]: Restrictions on network 0 are lifted if the sysctl > net.inet.ip.allow_zeronet is set to 1. This applies to packet forwarding > and ICMP echo. > > 224/4 (Experimental/"Class E") [2]: Restrictions on the Experimental > address class are lifted if the sysctl net.inet.ip.allow_experimental > is set to 1. This applies to packet forwarding and ICMP echo. > > 127/8 (loopback net) [3]: The size of the reservation for the loopback > network can be reduced from 127/8 to 127.0/16 using the sysctl > net.int.ip.loopback_mask. My current sysctl sets the mask, but that > is a little cumbersome; I should probably change the sysctl to allow > a mask length to be set. This change is limited to the kernel; the > IN_LOOPBACK macro uses the current mask in the kernel, but the default > mask at user level. Also, some user programs use IN_LOOPBACKNET along > with a Class A shift to crack this by hand. The kernel change affects > IP packet input and output as well as forwarding. > > The changes described above are all included in a single review for now, > although I would probably separate them before pushing them. (They > necessarily collide though.) The review is intended for comments only, > and is https://reviews.freebsd.org/D35741. I think it makes sense to > put these changes in -current in order to enable experimentation, but > I wanted to open the subject for discussion first. Mike, My first cut at this is in review: https://reviews.freebsd.org/D19316 Regards, Rod > > Changes are also being made in Linux, although I don't know their state. > > Note that there is a related proposal and change to allow use of the > lowest host on a network/subnet [4]. This change was essentially a bug > fix for FreeBSD, and is already in -current and 13.1-RELEASE. > > Mike > > [1] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0/01/ > > [2] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240/ > > [3] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/ > > [4] > https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-lowest-address/ > > > -- Rod Grimes rgri...@freebsd.org
Re: experimental support for IPv4 unicast extensions
In my opinion, these changes are definitely worth accepting. Removing barriers to deployment of 240/4 is a good thing. The changes are really simple, easy to understand and gated by sysctl which is sensible. I really hope we can move from 'default off' to 'default on' in a reasonably short period of time. Disclaimer: I work in a regional registry so I am probably biassed. While I might personally prefer people move to v6, I think this is a good body of code change to deploy. Coincidentally I was a co-author on an expired draft to un-reserve 240/4 many years ago, but it (foolishly perhaps) proposed private use, not global unicast. The kernel changes would however have been much the same. Thanks for doing this Mike. -George On Thu, Jul 7, 2022 at 8:07 AM Mike Karels wrote: > > I have been corresponding with the authors of Internet-Drafts that relax > restrictions on parts of the IPv4 address space to allow normal unicast > use, and I have FreeBSD changes to allow experimentation with these > updates. This message summarizes my changes, and solicits input. > > The changes are all controlled by sysctl, and default to "off". > The parts of the address space in question and the relevant changes: > > 0/8 (network 0) [1]: Restrictions on network 0 are lifted if the sysctl > net.inet.ip.allow_zeronet is set to 1. This applies to packet forwarding > and ICMP echo. > > 224/4 (Experimental/"Class E") [2]: Restrictions on the Experimental > address class are lifted if the sysctl net.inet.ip.allow_experimental > is set to 1. This applies to packet forwarding and ICMP echo. > > 127/8 (loopback net) [3]: The size of the reservation for the loopback > network can be reduced from 127/8 to 127.0/16 using the sysctl > net.int.ip.loopback_mask. My current sysctl sets the mask, but that > is a little cumbersome; I should probably change the sysctl to allow > a mask length to be set. This change is limited to the kernel; the > IN_LOOPBACK macro uses the current mask in the kernel, but the default > mask at user level. Also, some user programs use IN_LOOPBACKNET along > with a Class A shift to crack this by hand. The kernel change affects > IP packet input and output as well as forwarding. > > The changes described above are all included in a single review for now, > although I would probably separate them before pushing them. (They > necessarily collide though.) The review is intended for comments only, > and is https://reviews.freebsd.org/D35741. I think it makes sense to > put these changes in -current in order to enable experimentation, but > I wanted to open the subject for discussion first. > > Changes are also being made in Linux, although I don't know their state. > > Note that there is a related proposal and change to allow use of the > lowest host on a network/subnet [4]. This change was essentially a bug > fix for FreeBSD, and is already in -current and 13.1-RELEASE. > > Mike > > [1] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0/01/ > > [2] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240/ > > [3] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/ > > [4] > https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-lowest-address/ >
experimental support for IPv4 unicast extensions
I have been corresponding with the authors of Internet-Drafts that relax restrictions on parts of the IPv4 address space to allow normal unicast use, and I have FreeBSD changes to allow experimentation with these updates. This message summarizes my changes, and solicits input. The changes are all controlled by sysctl, and default to "off". The parts of the address space in question and the relevant changes: 0/8 (network 0) [1]: Restrictions on network 0 are lifted if the sysctl net.inet.ip.allow_zeronet is set to 1. This applies to packet forwarding and ICMP echo. 224/4 (Experimental/"Class E") [2]: Restrictions on the Experimental address class are lifted if the sysctl net.inet.ip.allow_experimental is set to 1. This applies to packet forwarding and ICMP echo. 127/8 (loopback net) [3]: The size of the reservation for the loopback network can be reduced from 127/8 to 127.0/16 using the sysctl net.int.ip.loopback_mask. My current sysctl sets the mask, but that is a little cumbersome; I should probably change the sysctl to allow a mask length to be set. This change is limited to the kernel; the IN_LOOPBACK macro uses the current mask in the kernel, but the default mask at user level. Also, some user programs use IN_LOOPBACKNET along with a Class A shift to crack this by hand. The kernel change affects IP packet input and output as well as forwarding. The changes described above are all included in a single review for now, although I would probably separate them before pushing them. (They necessarily collide though.) The review is intended for comments only, and is https://reviews.freebsd.org/D35741. I think it makes sense to put these changes in -current in order to enable experimentation, but I wanted to open the subject for discussion first. Changes are also being made in Linux, although I don't know their state. Note that there is a related proposal and change to allow use of the lowest host on a network/subnet [4]. This change was essentially a bug fix for FreeBSD, and is already in -current and 13.1-RELEASE. Mike [1] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0/01/ [2] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240/ [3] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/ [4] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-lowest-address/
