5.3. Transport Modes
libvirtsupports the following transport modes:
Transport Layer Security TLS 1.0 (SSL 3.1) authenticated and encrypted TCP/IP socket, usually listening on a public port number. To use this you will need to generate client and server certificates. The standard port is 16514.
UNIX domain sockets are only accessible on the local machine. Sockets are not encrypted, and use UNIX permissions or SELinux for authentication. The standard socket names are
/var/run/libvirt/libvirt-sock-ro (for read-only connections).
Transported over a Secure Shell protocol (SSH) connection. Requires Netcat (the nc package) installed. The libvirt daemon (
libvirtd) must be running on the remote machine. Port 22 must be open for SSH access. You should use some sort of SSH key management (for example, the
ssh-agent utility) or you will be prompted for a password.
ext parameter is used for any external program which can make a connection to the remote machine by means outside the scope of libvirt. This parameter is unsupported.
Unencrypted TCP/IP socket. Not recommended for production use, this is normally disabled, but an administrator can enable it for testing or use over a trusted network. The default port is 16509.
A Uniform Resource Identifier (URI) is used by
virsh and libvirt to connect to a remote host. URIs can also be used with the
--connect parameter for the
virsh command to execute single commands or migrations on remote hosts. Remote URIs are formed by taking ordinary local URIs and adding a host name or transport name. As a special case, using a URI scheme of 'remote', will tell the remote libvirtd server to probe for the optimal hypervisor driver. This is equivalent to passing a NULL URI for a local connection
Examples of remote management parameters
- Connect to a remote KVM host named
host2, using SSH transport and the SSH user name
virtuser.The connect command for each is
connect [<name>] [--readonly], where
<name>is a valid URI as explained here. For more information about the
virsh connectcommand refer to Section 14.1.5, “connect”
- Connect to a remote KVM hypervisor on the host named
- Connect to the local KVM hypervisor with a non-standard UNIX socket. The full path to the UNIX socket is supplied explicitly in this case.
- Connect to the libvirt daemon with an unencrypted TCP/IP connection to the server with the IP address 10.1.1.10 on port 5000. This uses the test driver with default settings.
Extra parameters can be appended to remote URIs. The table below Table 5.1, “Extra URI parameters” covers the recognized parameters. All other parameters are ignored. Note that parameter values must be URI-escaped (that is, a question mark (?) is appended before the parameter and special characters are converted into the URI format).
Table 5.1. Extra URI parameters
|Name||Transport mode||Description||Example usage|
|name||all modes||The name passed to the remote virConnectOpen function. The name is normally formed by removing transport, host name, port number, user name and extra parameters from the remote URI, but in certain very complex cases it may be better to supply the name explicitly.||name=qemu:///system|
|command||ssh and ext||The external command. For ext transport this is required. For ssh the default is ssh. The PATH is searched for the command.||command=/opt/openssh/bin/ssh|
|socket||unix and ssh||The path to the UNIX domain socket, which overrides the default. For ssh transport, this is passed to the remote netcat command (see netcat).||socket=/opt/libvirt/run/libvirt/libvirt-sock|
|no_verify||tls||If set to a non-zero value, this disables client checks of the server's certificate. Note that to disable server checks of the client's certificate or IP address you must change the libvirtd configuration.||no_verify=1|
|no_tty||ssh||If set to a non-zero value, this stops ssh from asking for a password if it cannot log in to the remote machine automatically . Use this when you do not have access to a terminal .||no_tty=1|