sshpoke/patch/ssh_fakehost.patch

--- cryptolib/ssh/tcpip.go	2023-11-18 22:20:50.609146922 +0300
+++ pkg/proto/ssh/tcpip.go	2023-11-18 22:19:08.891684669 +0300
@@ -101,14 +101,18 @@
 // ListenTCP requests the remote peer open a listening socket
 // on laddr. Incoming connections will be available by calling
 // Accept on the returned net.Listener.
-func (c *Client) ListenTCP(laddr *net.TCPAddr) (net.Listener, error) {
+func (c *Client) ListenTCP(laddr *net.TCPAddr, fakeHost ...string) (net.Listener, error) {
 	c.handleForwardsOnce.Do(c.handleForwards)
 	if laddr.Port == 0 && isBrokenOpenSSHVersion(string(c.ServerVersion())) {
 		return c.autoPortListenWorkaround(laddr)
 	}
 
+	host := laddr.IP.String()
+	if len(fakeHost) > 0 {
+		host = fakeHost[0]
+	}
 	m := channelForwardMsg{
-		laddr.IP.String(),
+		host,
 		uint32(laddr.Port),
 	}
 	// send message
@@ -133,7 +137,12 @@
 	}
 
 	// Register this forward, using the port number we obtained.
-	ch := c.forwards.add(laddr)
+	var ch chan forward
+	if len(fakeHost) > 0 {
+		ch = c.forwards.add(laddr, fakeHost[0])
+	} else {
+		ch = c.forwards.add(laddr)
+	}
 
 	return &tcpListener{laddr, c, ch}, nil
 }
@@ -142,7 +151,9 @@
 // forward requests and the tcpListeners.
 type forwardList struct {
 	sync.Mutex
-	entries []forwardEntry
+	fdm            sync.RWMutex
+	fakeDomainsMap map[string]string
+	entries        []forwardEntry
 }
 
 // forwardEntry represents an established mapping of a laddr on a
@@ -160,17 +171,30 @@
 	raddr net.Addr   // the raddr of the incoming connection
 }
 
-func (l *forwardList) add(addr net.Addr) chan forward {
+func (l *forwardList) add(addr net.Addr, fakeHost ...string) chan forward {
 	l.Lock()
 	defer l.Unlock()
 	f := forwardEntry{
 		laddr: addr,
 		c:     make(chan forward, 1),
 	}
+	if len(fakeHost) > 0 {
+		if l.fakeDomainsMap == nil {
+			l.fakeDomainsMap = make(map[string]string)
+		}
+		defer l.fdm.Unlock()
+		l.fdm.Lock()
+		l.fakeDomainsMap[fakeHost[0]] = l.ipFromAddr(addr)
+	}
 	l.entries = append(l.entries, f)
 	return f.c
 }
 
+func (l *forwardList) ipFromAddr(addr net.Addr) string {
+	host, _, _ := net.SplitHostPort(addr.String())
+	return host
+}
+
 // See RFC 4254, section 7.2
 type forwardedTCPPayload struct {
 	Addr       string
@@ -206,6 +230,15 @@
 				continue
 			}
 
+			l.fdm.RLock()
+			if addr, ok := l.fakeDomainsMap[payload.Addr]; ok {
+				payload.Addr = addr
+			}
+			if addr, ok := l.fakeDomainsMap[payload.OriginAddr]; ok {
+				payload.OriginAddr = addr
+			}
+			l.fdm.RUnlock()
+
 			// RFC 4254 section 7.2 specifies that incoming
 			// addresses should list the address, in string
 			// format. It is implied that this should be an IP