Impossible to disable IPv4
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
openssh (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Hardy |
Fix Released
|
Medium
|
Colin Watson |
Bug Description
Stable release update justification:
Impact: IPv4 access to IPv6-only OpenSSH servers cannot be disabled in Ubuntu 8.04 LTS. On systems where IPv4 connectivity is present but IPv6 is primary (which is currently fairly rare, but seems likely to become much more common over the remaining lifetime of 8.04) this will have confusing effects on access control.
Development branch: Fixed upstream for OpenSSH 4.9p1 (http://
Patch: See "Development branch" - the patch applies cleanly.
TEST CASE: Either of the two sshd_config options in the original report below should disable IPv4 access (test with 'ssh -4') and leave IPv6 access intact (test with 'ssh -6').
Regression potential: The most likely problem is a socket that becomes IPv6-only but was somehow important for IPv4 access. I suggest testing that IPv4 access remains unimpaired, and in particular I think it would be worth testing X forwarding.
Original report:
Last week I changed our infrastructure so that our ~20 Ubuntu boxes can only be managed with SSH via IPv6.
To do this I added "ListenAddress ::1" to sshd_config.
This seems to work fine on our 10.04LTS boxes (OpenSSH_5.3p1 Debian-3ubuntu), but this configuration does not work on our 8.04LTS boxes: they are still reachable via IPv4.
The same thing goes for "AddressFamily inet6", that options works on 10.04, but not on 8.04.
Classified as security bug, although I realise that probably not many are affected by this.
security vulnerability: | yes → no |
visibility: | private → public |
tags: |
added: verification-done removed: verification-needed |
tags: |
added: verification-done removed: verification-needed |
tags: | added: testcase |
Fixed in newer releases, as you say. I suspect that this may be the upstream commit responsible for fixing it, which would mean that it was fixed in OpenSSH 4.9p1:
http:// bazaar. launchpad. net/~vcs- imports/ openssh/ main/revision/ 5290
I've applied this patch to version 1:4.7p1- 8ubuntu2~ ppa1 in this archive:
https:/ /launchpad. net/~cjwatson/ +archive/ openssh
Could you please try it out and report whether it fixes this problem?