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Overview ¶
Package reversetunnel sets up persistent reverse tunnel between remote site and teleport proxy, when site agents dial to teleport proxy's socket and teleport proxy can connect to any server through this tunnel.
package reversetunnel provides interfaces for accessing remote clusters
via reverse tunnels and directly.
Reverse Tunnels
Proxy server Proxy agent
Reverse tunnel
+----------+ +---------+
| <----------------------+ |
| | | |
+-----+----------+ +---------+-----+ | | | | | | | | +----------------+ +---------------+
Proxy Cluster "A" Proxy Cluster "B"
Reverse tunnel is established from a cluster "B" Proxy to the a cluster "A" proxy, and clients of the cluster "A" can access servers of the cluster "B" via reverse tunnel connection, even if the cluster "B" is behind the firewall.
Multiple Proxies and Revese Tunnels ¶
With multiple proxies behind the load balancer, proxy agents will eventually discover and establish connections to all proxies in cluster.
* Initially Proxy Agent connects to Proxy 1. * Proxy 1 starts sending information about all available proxies that have not received connection from the Proxy Agent yet. This process is called "sending discovery request".
+----------+ | <--------+ | | | +----------+ | +-----------+ +----------+
Proxy 1 +-------------------------------+ |
| | | |
+-----------+ +----------+
Load Balancer Proxy Agent
+----------+ | | | | +----------+
Proxy 2
* Agent will use the discovery request to establish new connections and check if it has connected and "discovered" all the proxies specified
in the discovery request.
* Assuming that load balancer uses fair load balancing algorithm, agent will eventually discover and connect back to all the proxies.
+----------+ | <--------+ | | | +----------+ | +-----------+ +----------+
Proxy 1 +-------------------------------+ |
| | | | |
| +-----------+ +----------+
| Load Balancer Proxy Agent
+----------+ | | <--------+ | | +----------+
Proxy 2
Index ¶
Constants ¶
const ( // RemoteSiteStatusOffline indicates that site is considered as // offline, since it has missed a series of heartbeats RemoteSiteStatusOffline = "offline" // RemoteSiteStatusOnline indicates that site is sending heartbeats // at expected interval RemoteSiteStatusOnline = "online" )
const ConnectedEvent = "connected"
ConnectedEvent is used to indicate that reverse tunnel has connected
const RemoteAuthServer = "@remote-auth-server"
RemoteAuthServer is a special non-resolvable address that indicates we want a connection to the remote auth server.
Variables ¶
This section is empty.
Functions ¶
func NewHostCertificateCache ¶
NewHostCertificateCache creates a shared host certificate cache that is used by the forwarding server.
Types ¶
type Agent ¶
type Agent struct {
sync.RWMutex
*log.Entry
AgentConfig
// contains filtered or unexported fields
}
Agent is a reverse tunnel agent running as a part of teleport Proxies to establish outbound reverse tunnels to remote proxies.
There are two operation modes for agents: * Standard agent attempts to establish connection to any available proxy. Standard agent transitions between "connecting" -> "connected states. * Discovering agent attempts to establish connection to a subset of remote proxies (specified in the config via DiscoverProxies parameter.) Discovering agent transitions between "discovering" -> "discovered" states.
func NewAgent ¶
func NewAgent(cfg AgentConfig) (*Agent, error)
NewAgent returns a new reverse tunnel agent
type AgentConfig ¶
type AgentConfig struct {
// Addr is target address to dial
Addr utils.NetAddr
// RemoteCluster is a remote cluster name to connect to
RemoteCluster string
// Signers contains authentication signers
Signers []ssh.Signer
// Client is a client to the local auth servers
Client *auth.TunClient
// AccessPoint is a caching access point to the local auth servers
AccessPoint auth.AccessPoint
// Context is a parent context
Context context.Context
// DiscoveryC is a channel that receives discovery requests
// from reverse tunnel server
DiscoveryC chan *discoveryRequest
// Username is the name of this client used to authenticate on SSH
Username string
// DiscoverProxies is set when the agent is created in discovery mode
// and is set to connect to one of the target proxies from the list
DiscoverProxies []services.Server
// Clock is a clock passed in tests, if not set wall clock
// will be used
Clock clockwork.Clock
// EventsC is an optional events channel, used for testing purposes
EventsC chan string
}
AgentConfig holds configuration for agent
func (*AgentConfig) CheckAndSetDefaults ¶
func (a *AgentConfig) CheckAndSetDefaults() error
CheckAndSetDefaults checks parameters and sets default values
type AgentPool ¶ added in v1.0.0
AgentPool manages the pool of outbound reverse tunnel agents. The agent pool watches the reverse tunnel entries created by the admin and connects/disconnects to added/deleted tunnels.
func NewAgentPool ¶ added in v1.0.0
func NewAgentPool(cfg AgentPoolConfig) (*AgentPool, error)
NewAgentPool returns new isntance of the agent pool
func (*AgentPool) FetchAndSyncAgents ¶ added in v1.0.0
FetchAndSyncAgents executes one time fetch and sync request (used in tests instead of polling)
type AgentPoolConfig ¶ added in v1.0.0
type AgentPoolConfig struct {
// Client is client to the auth server this agent connects to receive
// a list of pools
Client *auth.TunClient
// AccessPoint is a lightweight access point
// that can optionally cache some values
AccessPoint auth.AccessPoint
// HostSigners is a list of host signers this agent presents itself as
HostSigners []ssh.Signer
// HostUUID is a unique ID of this host
HostUUID string
// Context is an optional context
Context context.Context
// Cluster is a cluster name
Cluster string
// Clock is a clock used to get time, if not set,
// system clock is used
Clock clockwork.Clock
}
AgentPoolConfig holds configuration parameters for the agent pool
func (*AgentPoolConfig) CheckAndSetDefaults ¶
func (cfg *AgentPoolConfig) CheckAndSetDefaults() error
CheckAndSetDefaults checks and sets defaults
type Config ¶
type Config struct {
// ID is the ID of this server proxy
ID string
// ListenAddr is a listening address for reverse tunnel server
ListenAddr utils.NetAddr
// HostSigners is a list of host signers
HostSigners []ssh.Signer
// HostKeyCallback
// Limiter is optional request limiter
Limiter *limiter.Limiter
// LocalAuthClient provides access to a full AuthClient for the local cluster.
LocalAuthClient auth.ClientI
// AccessPoint provides access to a subset of AuthClient of the cluster.
// AccessPoint caches values and can still return results during connection
// problems.
LocalAccessPoint auth.AccessPoint
// NewCachingAccessPoint returns new caching access points
// per remote cluster
NewCachingAccessPoint state.NewCachingAccessPoint
// DirectClusters is a list of clusters accessed directly
DirectClusters []DirectCluster
// Context is a signalling context
Context context.Context
// Clock is a clock used in the server, set up to
// wall clock if not set
Clock clockwork.Clock
}
Config is a reverse tunnel server configuration
func (*Config) CheckAndSetDefaults ¶
CheckAndSetDefaults checks parameters and sets default values
type DirectCluster ¶
type DirectCluster struct {
// Name is a cluster name
Name string
// Client is a client to the cluster
Client auth.ClientI
}
DirectCluster is used to access cluster directly
type RemoteSite ¶
type RemoteSite interface {
// DialAuthServer returns a net.Conn to the Auth Server of a site.
DialAuthServer() (net.Conn, error)
// Dial dials any address within the site network.
Dial(fromAddr, toAddr net.Addr, userAgent agent.Agent) (net.Conn, error)
// GetLastConnected returns last time the remote site was seen connected
GetLastConnected() time.Time
// GetName returns site name (identified by authority domain's name)
GetName() string
// GetStatus returns status of this site (either offline or connected)
GetStatus() string
// GetClient returns client connected to remote auth server
GetClient() (auth.ClientI, error)
// CachingAccessPoint returns access point that is lightweight
// but is resilient to auth server crashes
CachingAccessPoint() (auth.AccessPoint, error)
}
RemoteSite represents remote teleport site that can be accessed via teleport tunnel or directly by proxy
There are two implementations of this interface: local and remote sites.
type Server ¶
type Server interface {
// GetSites returns a list of connected remote sites
GetSites() []RemoteSite
// GetSite returns remote site this node belongs to
GetSite(domainName string) (RemoteSite, error)
// RemoveSite removes the site with the specified name from the list of connected sites
RemoveSite(domainName string) error
// Start starts server
Start() error
// CLose closes server's socket
Close() error
// Wait waits for server to close all outstanding operations
Wait()
}
Server is a TCP/IP SSH server which listens on an SSH endpoint and remote/local sites connect and register with it.
Source Files