Check compromised key blacklist in ssh or ssh-add, as well as in the

server (LP: #232391). To override the blacklist check in ssh
temporarily, use 'ssh -o UseBlacklistedKeys=yes'; there is no override
for the blacklist check in ssh-add.

1 files changed, 17 insertions, 0 deletions

diff --git a/ssh_config.5 b/ssh_config.5
index b048a54f5..411e9fd34 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -1056,6 +1056,23 @@ is not specified, it defaults to
 .Dq any .
 The default is
 .Dq any:any .
+.It Cm UseBlacklistedKeys
+Specifies whether
+.Xr ssh 1
+should use keys recorded in its blacklist of known-compromised keys (see
+.Xr ssh-vulnkey 1 )
+for authentication.
+If
+.Dq yes ,
+then attempts to use compromised keys for authentication will be logged but
+accepted.
+It is strongly recommended that this be used only to install new authorized
+keys on the remote system, and even then only with the utmost care.
+If
+.Dq no ,
+then attempts to use compromised keys for authentication will be prevented.
+The default is
+.Dq no .
 .It Cm UsePrivilegedPort
 Specifies whether to use a privileged port for outgoing connections.
 The argument must be