Following configuration causes ssh to spawn endless copies of itself when user tries to connect to the specified host. Host foo ProxyJump foo # or more generic Host * ProxyJump %h I have reproduced this on 7.9p1 on Suse Linux Enterprise Server 15 and on 7.4p1 on Debian Stretch (currently oldstable). Depending on limits configured on the server, this, like any other forkbomb, can cause all kinds of fun behavior on the local server. Perhaps the client could check for this edge case and avoid trying to make an impossible proxy connection.
*** Bug 3107 has been marked as a duplicate of this bug. ***
Created attachment 3356 [details] Detect simple proxyjump loops We have just committed the follow patch which should address this issue (at least for the simple case) and will be in the 8.3 release. Thanks for the report.
Shouldn't this check also verify it is not the same user? I often use -J <un-privileged-user>@<same host> <privileged-user>@<same host>.
Created attachment 3436 [details] Also check jumphost user I hadn't considered that use case but we could do that too.
Patch applied, thanks. It will be in the 8.4 release.
closing resolved bugs as of 8.6p1 release
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