diff --git a/p2p/node_info.go b/p2p/node_info.go
index a468443d..7c31aaf7 100644
--- a/p2p/node_info.go
+++ b/p2p/node_info.go
@@ -6,6 +6,8 @@ import (
 	"strings"
 
 	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/tendermint/tendermint/version"
 )
 
 const (
@@ -132,10 +134,10 @@ func (info DefaultNodeInfo) ValidateBasic() error {
 // CompatibleWith checks if two DefaultNodeInfo are compatible with eachother.
 // CONTRACT: two nodes are compatible if the major version matches and network match
 // and they have at least one channel in common.
-func (info DefaultNodeInfo) CompatibleWith(other_ NodeInfo) error {
-	other, ok := other_.(DefaultNodeInfo)
+func (info DefaultNodeInfo) CompatibleWith(otherInfo NodeInfo) error {
+	other, ok := otherInfo.(DefaultNodeInfo)
 	if !ok {
-		return fmt.Errorf("wrong NodeInfo type. Expected DefaultNodeInfo, got %v", reflect.TypeOf(other_))
+		return fmt.Errorf("wrong NodeInfo type. Expected DefaultNodeInfo, got %v", reflect.TypeOf(otherInfo))
 	}
 
 	iMajor, _, _, iErr := splitVersion(info.Version)
@@ -209,3 +211,252 @@ func splitVersion(version string) (string, string, string, error) {
 	}
 	return spl[0], spl[1], spl[2], nil
 }
+
+//--------------------------------------------------------------------------------------
+
+// NodeInfoV5 is the basic node information exchanged
+// between two peers during the Tendermint P2P handshake.
+type NodeInfoV5 struct {
+	Version  VersionInfo `json:"version"`
+	Address  AddressInfo `json:"id"`
+	Network  NetworkInfo `json:"network"`
+	Services ServiceInfo `json:"services"`
+}
+
+// VersionInfo contains all protocol and software version information for the node.
+type VersionInfo struct {
+	Protocol ProtocolVersion  `json:"protocol"`
+	Software version.Software `json:"software"`
+}
+
+// ProtocolVersion contains the p2p, block, and app protocol versions.
+type ProtocolVersion struct {
+	P2P   version.Protocol `json:"p2p"`
+	Block version.Protocol `json:"block"`
+
+	// Don't bother with App for now until we can update it live
+	// App   version.Protocol `json:"app"`
+}
+
+// AddressInfo contains info about the peers ID and network address.
+type AddressInfo struct {
+	// Authenticate
+	// TODO: replace with NetAddress ?
+	// Note NetAddress currently only has IP,
+	// but we may want DNS name here.
+	ID         ID     `json:"id"`          // authenticated identifier
+	ListenAddr string `json:"listen_addr"` // accepting incoming
+
+	// ASCIIText fields
+	Moniker string `json:"moniker"` // arbitrary moniker
+}
+
+// NetworkInfo contains info about the network this peer is operating on.
+// Currently, the only identifier is the ChainID, known here as the Name.
+type NetworkInfo struct {
+	Name string `json:"name"`
+}
+
+// ServiceInfo describes the services this peer offers to other peers and to users.
+type ServiceInfo struct {
+	Peers PeerServices `json:"peers`
+	Users UserServices `json:"users"`
+}
+
+// PeerServices describes the services this peer offers to other peers,
+// in terms of active Reactor channels.
+type PeerServices struct {
+	// Channels are HexBytes so easier to read as JSON
+	Channels cmn.HexBytes `json:"channels"` // channels this node knows about
+}
+
+// UserServices describes the set of services exposed to the user.
+type UserServices struct {
+	TxIndex    string `json:"tx_index"`
+	RPCAddress string `json:"rpc_address"`
+}
+
+//--------------------------------------------------------------------------
+
+func (info NodeInfoV5) ID() ID {
+	return info.Address.ID
+}
+
+func (info NodeInfoV5) ValidateBasic() error {
+
+	if err := info.Version.Validate(); err != nil {
+		return err
+	}
+
+	if err := info.Address.Validate(); err != nil {
+		return err
+	}
+
+	if err := info.Network.Validate(); err != nil {
+		return err
+	}
+
+	if err := info.Services.Validate(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Validate checks that the protocol versions are non-zero and that the software versions are ASCII.
+func (info VersionInfo) Validate() error {
+	//  TODO
+	//	ProtocolVersion - {P2P, Block} greater than 0
+	//	SoftwareVersion - ASCII
+	return nil
+}
+
+// Validate checks that the ListenAddr is well formed and that the moniker is ASCII.
+// The ID should have already been checked.
+func (info AddressInfo) Validate() error {
+	if _, err := sanitizeASCII(info.Moniker); err != nil {
+		return fmt.Errorf("Moniker %v", err)
+	}
+
+	// ensure ListenAddr is good
+	_, err := NewNetAddressString(IDAddressString(info.ID, info.ListenAddr))
+	return err
+
+}
+
+// Validate checks that the NetworkInfo.Name is ASCII.
+func (info NetworkInfo) Validate() error {
+	if _, err := sanitizeASCII(info.Name); err != nil {
+		return fmt.Errorf("Name %v", err)
+	}
+	return nil
+}
+
+// Validate validates the PeerServices and UserServices
+func (info ServiceInfo) Validate() error {
+
+	if err := info.Peers.Validate(); err != nil {
+		return err
+	}
+
+	if err := info.Users.Validate(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Validate checks that there are not too many channels or any duplicate channels.
+func (services PeerServices) Validate() error {
+	channelBytes := services.Channels
+	if len(channelBytes) > maxNumChannels {
+		return fmt.Errorf("Channels is too long (%v). Max is %v", len(channelBytes), maxNumChannels)
+	}
+
+	channels := make(map[byte]struct{})
+	for _, ch := range channelBytes {
+		_, ok := channels[ch]
+		if ok {
+			return fmt.Errorf("Channels contains duplicate channel id %v", ch)
+		}
+		channels[ch] = struct{}{}
+	}
+	return nil
+}
+
+func (services UserServices) Validate() error {
+	txIndex, err := sanitizeASCII(services.TxIndex)
+	if err != nil {
+		return fmt.Errorf("TxIndex %v", err)
+	}
+
+	if _, err := sanitizeASCII(services.RPCAddress); err != nil {
+		return fmt.Errorf("RPCAddress %v", err)
+	}
+
+	switch cmn.ASCIITrim(txIndex) {
+	case "on", "off":
+		// do nothing
+	default:
+		return fmt.Errorf("TxIndex should be either 'on' or 'off', got '%v'", txIndex)
+	}
+	return nil
+}
+
+func sanitizeASCII(input string) (string, error) {
+	if !cmn.IsASCIIText(input) || cmn.ASCIITrim(input) == "" {
+		return "", fmt.Errorf("must be valid non-empty ASCII text without tabs, but got %v", input)
+	}
+	return cmn.ASCIITrim(input), nil
+}
+
+// CompatibleWith checks if two NodeInfoV5 are compatible with eachother.
+// CONTRACT: two nodes are compatible if the major version matches and network match
+// and they have at least one channel in common.
+func (info NodeInfoV5) CompatibleWith(otherInfo NodeInfo) error {
+	other, ok := otherInfo.(NodeInfoV5)
+	if !ok {
+		return fmt.Errorf("wrong NodeInfo type. Expected DefaultNodeInfo, got %v", reflect.TypeOf(otherInfo))
+	}
+
+	// if we have no channels, we're just testing
+	ourChannels := info.Services.Peers.Channels
+	otherChannels := other.Services.Peers.Channels
+	if len(ourChannels) == 0 {
+		return nil
+	}
+
+	// nodes must have the same block version
+	if info.Version.Protocol.Block != other.Version.Protocol.Block {
+		return fmt.Errorf(
+			"Peer is running a different block protocol. Got %v, expected %v",
+			other.Version.Protocol.Block,
+			info.Version.Protocol.Block,
+		)
+	}
+
+	// nodes must be on the same network
+	if info.Network.Name != other.Network.Name {
+		return fmt.Errorf("Peer is on a different network. Got %v, expected %v", other.Network.Name, info.Network.Name)
+	}
+
+	// for each of our channels, check if they have it
+	found := false
+OUTER_LOOP:
+	for _, ch1 := range ourChannels {
+		for _, ch2 := range otherChannels {
+			if ch1 == ch2 {
+				found = true
+				break OUTER_LOOP // only need one
+			}
+		}
+	}
+	if !found {
+		return fmt.Errorf("Peer has no common channels. Our channels: %v ; Peer channels: %v", ourChannels, otherChannels)
+	}
+	return nil
+}
+
+// NetAddress returns a NetAddress derived from the NodeInfoV5 -
+// it includes the authenticated peer ID and the self-reported
+// ListenAddr. Note that the ListenAddr is not authenticated and
+// may not match that address actually dialed if its an outbound peer.
+func (info NodeInfoV5) NetAddress() *NetAddress {
+	netAddr, err := NewNetAddressString(IDAddressString(info.Address.ID, info.Address.ListenAddr))
+	if err != nil {
+		switch err.(type) {
+		case ErrNetAddressLookup:
+			// XXX If the peer provided a host name  and the lookup fails here
+			// we're out of luck.
+			// TODO: use a NetAddress in NodeInfoV5
+		default:
+			panic(err) // everything should be well formed by now
+		}
+	}
+	return netAddr
+}
+
+func (info NodeInfoV5) String() string {
+	return "TODO" // fmt.Sprintf("NodeInfoV5{id: %v, moniker: %v, network: %v [listen %v], version: %v (%v)}",
+	// info.ID, info.Moniker, info.Network, info.ListenAddr, info.Version, info.Other)
+}
diff --git a/version/version.go b/version/version.go
index 5a089141..0f3099ef 100644
--- a/version/version.go
+++ b/version/version.go
@@ -25,6 +25,11 @@ const (
 	ABCIVersion = ABCISemVer
 )
 
+type Software struct {
+	Tendermint string `json:"tendermint"`
+	App        string `json:"app"`
+}
+
 // Protocol is used for implementation agnostic versioning.
 type Protocol uint64