func (beacon *Beacon) keepAlive(conn ssh.Conn) (<-chan error, chan<- struct{}) {
logger := beacon.Logger.Session("keepalive")
errs := make(chan error, 1)
kas := time.NewTicker(5 * time.Second)
cancel := make(chan struct{})
go func() {
for {
// ignore reply; server may just not have handled it, since there's no
// standard keepalive request name
_, _, err := conn.SendRequest("keepalive", true, []byte("sup"))
if err != nil {
logger.Error("failed", err)
errs <- err
return
}
logger.Debug("ok")
select {
case <-kas.C:
case <-cancel:
errs <- nil
return
}
}
}()
return errs, cancel
}
//DialClient returns two channels where one returns a ssh.Client and the other and error
func DialClient(dial, expire time.Duration, ip string, conf *ssh.ClientConfig, retry <-chan struct{}) (*ssh.Client, error) {
flux.Report(nil, fmt.Sprintf("MakeDial for %s for dailing at %+s and expiring in %+s", conf.User, dial, expire))
cons := make(chan *ssh.Client)
errs := make(chan error)
var con net.Conn
var sc ssh.Conn
var chans <-chan ssh.NewChannel
var req <-chan *ssh.Request
var err error
flux.GoDefer("MakeDial", func() {
con, err = net.DialTimeout("tcp", ip, dial)
if err != nil {
flux.Report(err, fmt.Sprintf("MakeDial:Before for %s net.DailTimeout", ip))
errs <- err
return
}
sc, chans, req, err = ssh.NewClientConn(con, ip, conf)
if err != nil {
flux.Report(err, fmt.Sprintf("MakeDial:After for %s ssh.NewClientConn", ip))
errs <- err
return
}
flux.Report(nil, fmt.Sprintf("MakeDial initiating NewClient for %s", ip))
cons <- ssh.NewClient(sc, chans, req)
return
})
expiration := threshold(expire)
go func() {
for _ = range retry {
expiration = threshold(expire)
}
}()
select {
case err := <-errs:
flux.Report(err, fmt.Sprintf("NewClient Ending!"))
return nil, err
case som := <-cons:
flux.Report(nil, fmt.Sprintf("NewClient Created!"))
expiration = nil
return som, nil
case <-expiration:
flux.Report(nil, fmt.Sprintf("MakeDial Expired for %s!", ip))
defer con.Close()
if sc != nil {
sc.Close()
}
return nil, ErrTimeout
}
}
func OpenStream(conn ssh.Conn, remote string) (io.ReadWriteCloser, error) {
stream, reqs, err := conn.OpenChannel("chisel", []byte(remote))
if err != nil {
return nil, err
}
go ssh.DiscardRequests(reqs)
return stream, nil
}
func keepalive(conn ssh.Conn, ticker *time.Ticker, stopCh chan struct{}) {
for {
select {
case <-ticker.C:
_, _, _ = conn.SendRequest("*****@*****.**", true, nil)
case <-stopCh:
ticker.Stop()
return
}
}
}
func ProxyChannels(logger lager.Logger, conn ssh.Conn, channels <-chan ssh.NewChannel) {
logger = logger.Session("proxy-channels")
logger.Info("started")
defer logger.Info("completed")
defer conn.Close()
for newChannel := range channels {
logger.Info("new-channel", lager.Data{
"channelType": newChannel.ChannelType(),
"extraData": newChannel.ExtraData(),
})
targetChan, targetReqs, err := conn.OpenChannel(newChannel.ChannelType(), newChannel.ExtraData())
if err != nil {
logger.Error("failed-to-open-channel", err)
if openErr, ok := err.(*ssh.OpenChannelError); ok {
newChannel.Reject(openErr.Reason, openErr.Message)
} else {
newChannel.Reject(ssh.ConnectionFailed, err.Error())
}
continue
}
sourceChan, sourceReqs, err := newChannel.Accept()
if err != nil {
targetChan.Close()
continue
}
toTargetLogger := logger.Session("to-target")
toSourceLogger := logger.Session("to-source")
go func() {
helpers.Copy(toTargetLogger, nil, targetChan, sourceChan)
targetChan.CloseWrite()
}()
go func() {
helpers.Copy(toSourceLogger, nil, sourceChan, targetChan)
sourceChan.CloseWrite()
}()
go ProxyRequests(toTargetLogger, newChannel.ChannelType(), sourceReqs, targetChan)
go ProxyRequests(toSourceLogger, newChannel.ChannelType(), targetReqs, sourceChan)
}
}
/* handleConnRequests handles proxying requests read from reqs to the SSH
connection sc. info is used for logging */
func handleConnRequests(
reqs <-chan *ssh.Request,
c ssh.Conn,
info string,
) {
for r := range reqs {
go handleRequest(
r,
func(
name string,
wantReply bool,
payload []byte,
) (bool, []byte, error) {
return c.SendRequest(name, wantReply, payload)
},
func() error { return c.Close() },
info,
)
}
}
func ProxyGlobalRequests(logger lager.Logger, conn ssh.Conn, reqs <-chan *ssh.Request) {
logger = logger.Session("proxy-global-requests")
logger.Info("started")
defer logger.Info("completed")
for req := range reqs {
logger.Info("request", lager.Data{
"type": req.Type,
"wantReply": req.WantReply,
"payload": req.Payload,
})
success, reply, err := conn.SendRequest(req.Type, req.WantReply, req.Payload)
if err != nil {
logger.Error("send-request-failed", err)
continue
}
if req.WantReply {
req.Reply(success, reply)
}
}
}
func (c *comm) reconnect() (err error) {
if c.conn != nil {
c.conn.Close()
}
// Set the conn and client to nil since we'll recreate it
c.conn = nil
c.client = nil
log.Printf("reconnecting to TCP connection for SSH")
c.conn, err = c.config.Connection()
if err != nil {
// Explicitly set this to the REAL nil. Connection() can return
// a nil implementation of net.Conn which will make the
// "if c.conn == nil" check fail above. Read here for more information
// on this psychotic language feature:
//
// http://golang.org/doc/faq#nil_error
c.conn = nil
log.Printf("reconnection error: %s", err)
return
}
log.Printf("handshaking with SSH")
// Default timeout to 1 minute if it wasn't specified (zero value). For
// when you need to handshake from low orbit.
var duration time.Duration
if c.config.HandshakeTimeout == 0 {
duration = 1 * time.Minute
} else {
duration = c.config.HandshakeTimeout
}
connectionEstablished := make(chan struct{}, 1)
var sshConn ssh.Conn
var sshChan <-chan ssh.NewChannel
var req <-chan *ssh.Request
go func() {
sshConn, sshChan, req, err = ssh.NewClientConn(c.conn, c.address, c.config.SSHConfig)
close(connectionEstablished)
}()
select {
case <-connectionEstablished:
// We don't need to do anything here. We just want select to block until
// we connect or timeout.
case <-time.After(duration):
if c.conn != nil {
c.conn.Close()
}
if sshConn != nil {
sshConn.Close()
}
return ErrHandshakeTimeout
}
if err != nil {
log.Printf("handshake error: %s", err)
return
}
log.Printf("handshake complete!")
if sshConn != nil {
c.client = ssh.NewClient(sshConn, sshChan, req)
}
c.connectToAgent()
return
}
/* handleChan handles a single channel request from sc, proxying it to the
client. General logging messages will be written to lg, and channel-specific
data and messages will be written to a new file in ldir. */
func handleChan(
nc ssh.NewChannel,
client ssh.Conn,
ldir string,
lg *log.Logger,
direction string,
) {
/* Log the channel request */
crl := fmt.Sprintf(
"Type:%q Data:%q Direction:%q",
nc.ChannelType(),
nc.ExtraData(),
direction,
)
/* Pass to server */
cc, creqs, err := client.OpenChannel(
nc.ChannelType(),
nc.ExtraData(),
)
if nil != err {
go rejectChannel(err, crl, nc, lg)
return
}
defer cc.Close()
/* Make channel to attacker, defer close */
ac, areqs, err := nc.Accept()
if nil != err {
lg.Printf(
"Unable to accept channel request of type %q: %v",
nc.ChannelType(),
err,
)
return
}
defer ac.Close()
/* Channel worked, make a logger for it */
clg, lf, clgn, err := logChannel(ldir, nc)
if nil != err {
lg.Printf(
"Unable to open log file for channel of type %q:%v",
nc.ChannelType(),
err,
)
return
}
defer lf.Close()
clg.Printf("Start of log")
/* Proxy requests on channels */
go handleReqs(areqs, Channel{oc: cc}, clg, "attacker->server")
go handleReqs(creqs, Channel{oc: ac}, clg, "server->attacker")
/* Log the channel */
lg.Printf("Channel %s Log:%q", crl, clgn)
/* Proxy comms */
wg := make(chan int, 4)
go ProxyChannel(
ac,
cc,
clg,
"server->attacker",
wg,
1,
)
go ProxyChannel(
cc,
ac,
clg,
"attacker->server",
wg,
1,
)
go ProxyChannel(
cc.Stderr(),
ac.Stderr(),
clg,
"attacker-(err)->server",
wg,
0,
)
go ProxyChannel(
ac.Stderr(),
cc.Stderr(),
clg,
"server-(err)->attacker",
wg,
0,
)
sum := 0
for i := range wg {
sum += i
if 2 <= sum {
break
}
}
/* TODO: Proxy comms */
}
/* handleChannel proxies a channel request command or shell to the ssh
connection sc. */
func handleNewChannel(cr ssh.NewChannel, sc ssh.Conn, info string) {
log.Printf(
"%v Type:%q Data:%q NewChannel",
info,
cr.ChannelType(),
cr.ExtraData(),
)
/* Make the same request to the other side */
och, oreqs, err := sc.OpenChannel(cr.ChannelType(), cr.ExtraData())
if nil != err {
/* If we can't log it, and reject the client */
oe, ok := err.(*ssh.OpenChannelError)
var (
reason ssh.RejectionReason
message string
)
if !ok {
log.Printf(
"%v Type:%q Data:%q Unable to open channel: "+
"%v",
info,
cr.ChannelType(),
cr.ExtraData(),
err,
)
reason = ssh.ConnectionFailed
message = "Fail"
message = err.Error()
} else {
log.Printf(
"%v Type:%q Data:%q Reason:%q Message:%q "+
"Unable to open channel",
info,
cr.ChannelType(),
cr.ExtraData(),
oe.Reason.String(),
oe.Message,
)
reason = oe.Reason
message = oe.Message
}
if err := cr.Reject(reason, message); nil != err {
log.Printf(
"%v Unable to pass on channel rejecton "+
"request: %v",
info,
err,
)
}
return
}
defer och.Close()
/* Accept the channel request from the requestor */
rch, rreqs, err := cr.Accept()
if nil != err {
log.Printf(
"%v Unable to accept request for a channel of type "+
"%q: %v",
cr.ChannelType(),
info,
err,
)
return
}
defer rch.Close()
/* Handle passing requests between channels */
hcrinfo := fmt.Sprintf(" %v ChannelType:%q", info, cr.ChannelType())
go handleChannelRequests(
rreqs,
och,
hcrinfo+" ReqDir:AsDirection",
)
go handleChannelRequests(
oreqs,
rch,
hcrinfo+" ReqDir:AgainstDirection",
)
log.Printf(
"%v Type:%q Data:%q Opened",
info,
cr.ChannelType(),
cr.ExtraData(),
)
/* For now, print out read data */
done := make(chan struct{}, 4)
go copyOut(och, rch, done)
go copyOut(rch, och, done)
go copyOut(och.Stderr(), rch.Stderr(), done)
go copyOut(rch.Stderr(), och.Stderr(), done)
/* Wait for a pipe to break */
<-done
fmt.Printf("\nDone.\n")
}
/* waitChan puts an empty struct in wc when c's Wait method returns. */
func waitChan(c ssh.Conn, wc chan<- struct{}) {
c.Wait()
wc <- struct{}{}
}
