#616610 openssh-client: ssh config does not like IPv6 link local address as hostname anymore (worked before today's update)

Package:
openssh-client
Source:
openssh
Description:
secure shell (SSH) client, for secure access to remote machines
Submitter:
Linus Lüssing
Date:
2025-08-17 17:47:40 UTC
Severity:
normal
Tags:
#616610#5
Date:
2011-03-05 22:59:21 UTC
From:
To:
Hi everyone,

I did an aptitude full-upgrade today and since then an IPv6
specific functionality does not work anymore. I'm having an IPv6 link
local address in my ssh config file for a hostname:

########## ~/.ssh/config ###########
[...]
Host vm1
	Hostname fe80::4:64ff:fea4:39b1%br0
	User mesh-node
	StrictHostKeyChecking no
	IdentityFile ~/.ssh/vm_rsa
[...]
####################################

Since 1:5.8p1-2 I get the following error message:
	$ ssh vm1
	percent_expand: unknown key %b


This worked fine with openssh-client 1:5.5p1-6 before.

Cheers, Linus
#616610#10
Date:
2011-07-09 09:37:05 UTC
From:
To:
I discovered that openssh-5.8 seems to support parameter expansion by
variables which breaks older configurations with IPv6 link-local
addresses as Linus Lüssing observed.

The good news:
Double %% instead of single % will work (observed on 1:5.8p1-1ubuntu3).
like
Hostname fe80::4:64ff:fea4:39b1%%br0
Hostname fe80::0dd:affe:fea4:3ea1%%wlan0 # (real address changed for privacy reasons)

The bad:
The %% syntax does not work in openssh-5.5

Ah, I found a note about that in http://www.openssh.org/txt/release-5.6
"Expand %h to the hostname in ssh_config Hostname options."

So I kindly ask the packet maintainer to add a warning to everyone
upgrading from openssh below 5.6. But as this upstream upgrade will
break some user configurations this might not be sufficient...


Olaf