ProxyCommand ssh -aY bastion 'nc -w 900 `echo %h | sed s/\\.bast$//` %p'
Don’t do this. Instead, do
ProxyCommand ssh -W `echo %h:%p | sed s/\\/bast:/:/` bast
-W is “netcat mode” which was added back in 5.4.
Don’t do this. Instead, do
-W is “netcat mode” which was added back in 5.4.