Bug 3179

Summary: sshd bind function and IPv6 neighbor discovery
Product: Portable OpenSSH Reporter: kircher <kircherlike>
Component: sshdAssignee: Assigned to nobody <unassigned-bugs>
Status: CLOSED WONTFIX    
Severity: normal CC: djm
Priority: P5    
Version: 8.2p1   
Hardware: ARM64   
OS: Linux   

Description kircher 2020-06-08 22:02:21 AEST 
When I configure a service file in systemd for my /usr/sbin/sshd file, 
I write a dependency statement such as After=network-online.target. 

...
[Unit]
Description=OpenSSH server daemon
Documentation=man:sshd(8) man:sshd_config(5)
After=network-online.target sshd-keygen.target
Wants=sshd-keygen.target
...

However, when I configured some special IPv6 addresses for my network adapter,
 I restarted the machine and found that the bind function of sshd failed to 
 bind such IP addresses. The reason is that when the bind function is called, 
 the IPv6 address is not in the neighbor discovery state 
 and does not take effect completely. 
 
 Therefore, I wonder whether the bind function policy in sshd can be modified accordingly.
 For example, the network address status can be detected first.
Comment 1 Damien Miller 2020-06-26 14:03:52 AEST 
Enforcing the external preconditions are met is the job of systemd and/or NetworkManager, not sshd.

I think they already offer a knob that allows this, e.g. this bug report from a similar situation https://bugzilla.redhat.com/show_bug.cgi?id=1713478#c11
Comment 2 Damien Miller 2021-03-04 09:52:50 AEDT 
close bugs that were resolved in OpenSSH 8.5 release cycle