When configuring RADIUS to use IPv6 as connection to the server
```
set system login radius server 2001:db8::4 key '9LMVCtPYpG'
set system login radius source-address '2001:db8::1'
```
Will result in:
```
Jan 10 13:39:04 sshd[13552]: pam_radius_auth(sshd:auth): Failed looking up source IP address [2001:db8::1] for server [2001:db8::4]:1812 (error=System error)
Jan 10 13:39:04 sshd[13552]: pam_radius_auth(sshd:auth): Failed looking up source IP address [2001:db8::1] for server [2001:db8::5]:1812 (error=System error)
```
```
vyos@vyos# sudo cat /etc/pam_radius_auth.conf
### Automatically generated by system_login.py ###
# RADIUS configuration file
# server[:port] shared_secret timeout source_ip
[2001:db8::4]:1812 9LMVCtPYpG 2 [2001:db8::1]
priv-lvl 15
mapped_priv_user radius_priv_user
```
The source address is not allowed to be in `[]`