Re: qemu+ssh connections to a remote libvirt fail as ssh banner configured

On Thu, Feb 10, 2022 at 09:33:38AM +0100, Michal Prívozník wrote: > On 2/10/22 09:02, Daniel P. Berrangé wrote: > > On Thu, Feb 10, 2022 at 09:52:52AM +0800, Yalan Zhang wrote: > >> Hi there, > >> > >> I have a system configured with ssh login banner like as below: > >> # cat ~/.bashrc > >> ... > >> echo > >> "=================================================================================" > >> echo "====== This machine is occupied by xxx for testing now. If you are > >> about to use it, contact xxx first ======" > >> echo > >> "=================================================================================" > >> > >> It works as expected that whenever someone logs into this system by ssh, > >> he/she will see this warning message. > >> But it seems such settings will impact a virsh client connection with ssh, > >> when I try to connect the libvirt daemon on this system, it will error out : > >> # virsh -c qemu+ssh://${my_host}/system list --all > >> root@${my_host}'s password: > >> error: failed to connect to the hypervisor > >> error: packet 1027423545 bytes received from server too large, want 33554432 > > > > Libvirt is tunnelling an RPC protocol over the SSH connection. > > Your bashrc is printing this text onto the SSH conmnection and > > that corrupts the libvirt RPC protocol. > > > > If you want to print something whjen people login use the > > /etc/motd file which is designed for this pupose, don't > > print stuff from a .bashrc. Libvirt gives the options to > > SSH that prevent display of /etc/motd contents, so that > > its RPC protocol doesn't get corrupted. > > One more thing, I wasn't able to reproduce when virt-ssh-helper was > used. But maybe I wasn't trying hard enough. That should be affected in exactly the same way. It still relies on stdout/stdin being clean data channels. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|