Update examples to use dynamic host IP instead of hardcoded localhost

examples/advanced/network_discover.py

@@ -17,9 +17,22 @@ try:
         get_wildcard_address,
     )
 except ImportError:
-    # Fallbacks if utilities are missing
+    # Fallbacks if utilities are missing - use minimal network discovery
+    import socket
     def get_available_interfaces(port: int, protocol: str = "tcp"):
-        return [Multiaddr(f"/ip4/127.0.0.1/{protocol}/{port}")]
+        # Try to get local network interfaces, fallback to loopback
+        addrs = []
+        try:
+            # Get hostname IP (better than hardcoded localhost)
+            hostname = socket.gethostname()
+            local_ip = socket.gethostbyname(hostname)
+            if local_ip != "127.0.0.1":
+                addrs.append(Multiaddr(f"/ip4/{local_ip}/{protocol}/{port}"))
+        except exception:
+            pass
+        # Always include loopback as fallback
+        addrs.append(Multiaddr(f"/ip4/127.0.0.1/{protocol}/{port}"))
+        return addrs
 
     def expand_wildcard_address(addr: Multiaddr, port: int | None = None):
         if port is None:
@@ -28,6 +41,12 @@ except ImportError:
         return [Multiaddr(addr_str + f"/{port}")]
 
     def get_optimal_binding_address(port: int, protocol: str = "tcp"):
+        # Try to get a non-loopback address first
+        interfaces = get_available_interfaces(port, protocol)
+        for addr in interfaces:
+            if "127.0.0.1" not in str(addr):
+                return addr
+        # Fallback to loopback if no other interfaces found
         return Multiaddr(f"/ip4/127.0.0.1/{protocol}/{port}")
 
     def get_wildcard_address(port: int, protocol: str = "tcp"):

examples/bootstrap/bootstrap.py

@@ -120,7 +120,7 @@ def main() -> None:
     Usage:
         python bootstrap.py -p 8000
         python bootstrap.py -p 8001 --custom-bootstrap \\
-            "/ip4/127.0.0.1/tcp/8000/p2p/QmYourPeerID"
+            "/ip4/[HOST_IP]/tcp/8000/p2p/QmYourPeerID"
     """
 
     parser = argparse.ArgumentParser(

examples/chat/chat.py

@@ -110,7 +110,7 @@ def main() -> None:
     where <DESTINATION> is the multiaddress of the previous listener host.
     """
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/[HOST_IP]/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
     parser = argparse.ArgumentParser(description=description)
     parser.add_argument("-p", "--port", default=0, type=int, help="source port number")

examples/doc-examples/example_encryption_insecure.py

@@ -1,6 +1,5 @@
 import secrets
 
-import multiaddr
 import trio
 
 from libp2p import (
@@ -9,9 +8,10 @@ from libp2p import (
 from libp2p.crypto.secp256k1 import (
     create_new_key_pair,
 )
-from libp2p.security.insecure.transport import (
+from libp2p.security.insecure.transport import PLAINTEXT_PROTOCOL_ID, Transport
-    PLAINTEXT_PROTOCOL_ID,
+from libp2p.utils.address_validation import (
-    InsecureTransport,
+    get_available_interfaces,
+    get_optimal_binding_address,
 )
 
 
@@ -21,7 +21,7 @@ async def main():
     key_pair = create_new_key_pair(secret)
 
     # Create an insecure transport (not recommended for production)
-    insecure_transport = InsecureTransport(
+    insecure_transport = Transport(
         # local_key_pair: The key pair used for libp2p identity
         local_key_pair=key_pair,
         # secure_bytes_provider: Optional function to generate secure random bytes
@@ -38,17 +38,19 @@ async def main():
     # Create a host with the key pair and insecure transport
     host = new_host(key_pair=key_pair, sec_opt=security_options)
 
-    # Configure the listening address
+    # Configure the listening address using the new paradigm
     port = 8000
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/tcp/{port}")
+    listen_addrs = get_available_interfaces(port)
+    optimal_addr = get_optimal_binding_address(port)
 
     # Start the host
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=listen_addrs):
         print(
             "libp2p has started with insecure transport "
             "(not recommended for production)"
         )
         print("libp2p is listening on:", host.get_addrs())
+        print(f"Optimal address: {optimal_addr}")
         # Keep the host running
         await trio.sleep_forever()
 

examples/doc-examples/example_encryption_noise.py

@@ -1,6 +1,5 @@
 import secrets
 
-import multiaddr
 import trio
 
 from libp2p import (
@@ -13,6 +12,10 @@ from libp2p.security.noise.transport import (
     PROTOCOL_ID as NOISE_PROTOCOL_ID,
     Transport as NoiseTransport,
 )
+from libp2p.utils.address_validation import (
+    get_available_interfaces,
+    get_optimal_binding_address,
+)
 
 
 async def main():
@@ -39,14 +42,16 @@ async def main():
     # Create a host with the key pair and Noise security
     host = new_host(key_pair=key_pair, sec_opt=security_options)
 
-    # Configure the listening address
+    # Configure the listening address using the new paradigm
     port = 8000
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/tcp/{port}")
+    listen_addrs = get_available_interfaces(port)
+    optimal_addr = get_optimal_binding_address(port)
 
     # Start the host
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=listen_addrs):
         print("libp2p has started with Noise encryption")
         print("libp2p is listening on:", host.get_addrs())
+        print(f"Optimal address: {optimal_addr}")
         # Keep the host running
         await trio.sleep_forever()
 

examples/doc-examples/example_encryption_secio.py

@@ -1,6 +1,5 @@
 import secrets
 
-import multiaddr
 import trio
 
 from libp2p import (
@@ -13,6 +12,10 @@ from libp2p.security.secio.transport import (
     ID as SECIO_PROTOCOL_ID,
     Transport as SecioTransport,
 )
+from libp2p.utils.address_validation import (
+    get_available_interfaces,
+    get_optimal_binding_address,
+)
 
 
 async def main():
@@ -32,14 +35,16 @@ async def main():
     # Create a host with the key pair and SECIO security
     host = new_host(key_pair=key_pair, sec_opt=security_options)
 
-    # Configure the listening address
+    # Configure the listening address using the new paradigm
     port = 8000
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/tcp/{port}")
+    listen_addrs = get_available_interfaces(port)
+    optimal_addr = get_optimal_binding_address(port)
 
     # Start the host
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=listen_addrs):
         print("libp2p has started with SECIO encryption")
         print("libp2p is listening on:", host.get_addrs())
+        print(f"Optimal address: {optimal_addr}")
         # Keep the host running
         await trio.sleep_forever()
 

examples/doc-examples/example_net_stream.py

@@ -234,7 +234,7 @@ async def run_enhanced_demo(
 
 def main() -> None:
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/[HOST_IP]/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
 
     parser = argparse.ArgumentParser(

examples/doc-examples/example_peer_discovery.py

@@ -1,6 +1,5 @@
 import secrets
 
-import multiaddr
 import trio
 
 from libp2p import (
@@ -16,6 +15,10 @@ from libp2p.security.noise.transport import (
     PROTOCOL_ID as NOISE_PROTOCOL_ID,
     Transport as NoiseTransport,
 )
+from libp2p.utils.address_validation import (
+    get_available_interfaces,
+    get_optimal_binding_address,
+)
 
 
 async def main():
@@ -42,14 +45,16 @@ async def main():
     # Create a host with the key pair, Noise security, and mplex multiplexer
     host = new_host(key_pair=key_pair, sec_opt=security_options)
 
-    # Configure the listening address
+    # Configure the listening address using the new paradigm
     port = 8000
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/tcp/{port}")
+    listen_addrs = get_available_interfaces(port)
+    optimal_addr = get_optimal_binding_address(port)
 
     # Start the host
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=listen_addrs):
         print("libp2p has started")
         print("libp2p is listening on:", host.get_addrs())
+        print(f"Optimal address: {optimal_addr}")
 
         # Connect to bootstrap peers manually
         bootstrap_list = [

examples/doc-examples/example_quic_transport.py

@@ -1,6 +1,5 @@
 import secrets
 
-import multiaddr
 import trio
 
 from libp2p import (
@@ -9,6 +8,10 @@ from libp2p import (
 from libp2p.crypto.secp256k1 import (
     create_new_key_pair,
 )
+from libp2p.utils.address_validation import (
+    get_available_interfaces,
+    get_optimal_binding_address,
+)
 
 
 async def main():
@@ -19,14 +22,24 @@ async def main():
     # Create a host with the key pair
     host = new_host(key_pair=key_pair, enable_quic=True)
 
-    # Configure the listening address
+    # Configure the listening address using the new paradigm
     port = 8000
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/udp/{port}/quic-v1")
+    listen_addrs = get_available_interfaces(port, protocol="udp")
+    # Convert TCP addresses to QUIC-v1 addresses
+    quic_addrs = []
+    for addr in listen_addrs:
+        addr_str = str(addr).replace("/tcp/", "/udp/") + "/quic-v1"
+        from multiaddr import Multiaddr
+        quic_addrs.append(Multiaddr(addr_str))
+
+    optimal_addr = get_optimal_binding_address(port, protocol="udp")
+    optimal_quic_str = str(optimal_addr).replace("/tcp/", "/udp/") + "/quic-v1"
 
     # Start the host
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=quic_addrs):
         print("libp2p has started with QUIC transport")
         print("libp2p is listening on:", host.get_addrs())
+        print(f"Optimal address: {optimal_quic_str}")
         # Keep the host running
         await trio.sleep_forever()
 

examples/echo/echo.py

@@ -125,7 +125,7 @@ def main() -> None:
     where <DESTINATION> is the multiaddress of the previous listener host.
     """
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/[HOST_IP]/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
     parser = argparse.ArgumentParser(description=description)
     parser.add_argument("-p", "--port", default=0, type=int, help="source port number")

examples/echo/echo_quic.py

@@ -43,13 +43,22 @@ async def _echo_stream_handler(stream: INetStream) -> None:
 
 async def run_server(port: int, seed: int | None = None) -> None:
     """Run echo server with QUIC transport."""
-    from libp2p.utils.address_validation import find_free_port
+    from libp2p.utils.address_validation import (
+        find_free_port,
+        get_available_interfaces,
+        get_optimal_binding_address,
+    )
 
     if port <= 0:
         port = find_free_port()
 
-    # For QUIC, we need to use UDP addresses - use loopback for security
+    # For QUIC, we need UDP addresses - use the new address paradigm
-    listen_addr = Multiaddr(f"/ip4/127.0.0.1/udp/{port}/quic")
+    tcp_addrs = get_available_interfaces(port)
+    # Convert TCP addresses to QUIC addresses
+    quic_addrs = []
+    for addr in tcp_addrs:
+        addr_str = str(addr).replace("/tcp/", "/udp/") + "/quic"
+        quic_addrs.append(Multiaddr(addr_str))
 
     if seed:
         import random
@@ -69,7 +78,7 @@ async def run_server(port: int, seed: int | None = None) -> None:
     )
 
     # Server mode: start listener
-    async with host.run(listen_addrs=[listen_addr]):
+    async with host.run(listen_addrs=quic_addrs):
         try:
             print(f"I am {host.get_id().to_string()}")
             host.set_stream_handler(PROTOCOL_ID, _echo_stream_handler)
@@ -81,11 +90,13 @@ async def run_server(port: int, seed: int | None = None) -> None:
             for addr in all_addrs:
                 print(f"{addr}")
 
-            # Use the first address as the default for the client command
+            # Use optimal address for the client command
-            default_addr = all_addrs[0]
+            optimal_tcp = get_optimal_binding_address(port)
+            optimal_quic_str = str(optimal_tcp).replace("/tcp/", "/udp/") + "/quic"
+            optimal_quic_with_peer = f"{optimal_quic_str}/p2p/{host.get_id().to_string()}"
             print(
                 f"\nRun this from the same folder in another console:\n\n"
-                f"python3 ./examples/echo/echo_quic.py -d {default_addr}\n"
+                f"python3 ./examples/echo/echo_quic.py -d {optimal_quic_with_peer}\n"
             )
             print("Waiting for incoming QUIC connections...")
             await trio.sleep_forever()
@@ -167,7 +178,7 @@ def main() -> None:
     where <DESTINATION> is the QUIC multiaddress of the previous listener host.
     """
 
-    example_maddr = "/ip4/127.0.0.1/udp/8000/quic/p2p/QmQn4SwGkDZKkUEpBRBv"
+    example_maddr = "/ip4/[HOST_IP]/udp/8000/quic/p2p/QmQn4SwGkDZKkUEpBRBv"
 
     parser = argparse.ArgumentParser(description=description)
     parser.add_argument("-p", "--port", default=0, type=int, help="UDP port number")

examples/identify/identify.py

@@ -262,7 +262,7 @@ def main() -> None:
     """
 
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8888/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/[HOST_IP]/tcp/8888/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
 
     parser = argparse.ArgumentParser(description=description)

examples/identify_push/identify_push_demo.py

@@ -36,6 +36,9 @@ from libp2p.identity.identify_push import (
 from libp2p.peer.peerinfo import (
     info_from_p2p_addr,
 )
+from libp2p.utils.address_validation import (
+    get_available_interfaces,
+)
 
 # Configure logging
 logger = logging.getLogger(__name__)
@@ -207,13 +210,13 @@ async def main() -> None:
         ID_PUSH, create_custom_identify_push_handler(host_2, "Host 2")
     )
 
-    # Start listening on random ports using the run context manager
+    # Start listening on available interfaces using random ports
-    listen_addr_1 = multiaddr.Multiaddr("/ip4/127.0.0.1/tcp/0")
+    listen_addrs_1 = get_available_interfaces(0)  # 0 for random port
-    listen_addr_2 = multiaddr.Multiaddr("/ip4/127.0.0.1/tcp/0")
+    listen_addrs_2 = get_available_interfaces(0)  # 0 for random port
 
     async with (
-        host_1.run([listen_addr_1]),
+        host_1.run(listen_addrs_1),
-        host_2.run([listen_addr_2]),
+        host_2.run(listen_addrs_2),
         trio.open_nursery() as nursery,
     ):
         # Start the peer-store cleanup task

examples/identify_push/identify_push_listener_dialer.py

@@ -14,7 +14,7 @@ Usage:
     python identify_push_listener_dialer.py
 
     # Then in another console, run as a dialer (default port 8889):
-    python identify_push_listener_dialer.py -d /ip4/127.0.0.1/tcp/8888/p2p/PEER_ID
+    python identify_push_listener_dialer.py -d /ip4/[HOST_IP]/tcp/8888/p2p/PEER_ID
     (where PEER_ID is the peer ID displayed by the listener)
 """
 
@@ -291,10 +291,12 @@ async def run_dialer(
         identify_push_handler_for(host, use_varint_format=use_varint_format),
     )
 
-    # Start listening on a different port
+    # Start listening on available interfaces
-    listen_addr = multiaddr.Multiaddr(f"/ip4/127.0.0.1/tcp/{port}")
+    from libp2p.utils.address_validation import get_available_interfaces
 
-    async with host.run([listen_addr]):
+    listen_addrs = get_available_interfaces(port)
+
+    async with host.run(listen_addrs):
         logger.info("Dialer host ready!")
         print("Dialer host ready!")
 

examples/ping/ping.py

@@ -118,7 +118,7 @@ def main() -> None:
     """
 
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/[HOST_IP]/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
 
     parser = argparse.ArgumentParser(description=description)