MPTCP Proxies & Anchors

Georg Hampel & Thierry KleinBell Labs – Alcatel-Lucent

draft_hampel_mptcp_proxies_anchors_00

Host

Proxy Anchor

• Incremental deployment • Protocol NAT• Some BBM mobility scenarios

MPTCP Network Functions on MPTCP Network Nodes

Host

Host

MPTCP

MPTCP

TCP

MPTCP

Host

MPTCP

MPTCP

MPTCP

Host

Host

MPTCP

Host

Host

Anchor

MPTCP

Host

Host

MPTCP

Host

Anchor

MPTCP

Examples for MPTCP Anchor

Simultaneous Mobility Mobility + Firewall

MPTCP NN

MPTCP NN

MPTCP NN

Femto

Where will MPTCP NNs reside?

Carrier Carrier

AP ISP

eNodeB

LTE

Wi-Fi

• In 3G/4G carrier networks for traffic offload• Multiple MPTCP NNs may lie in a chain

Issues:

• MPTCP-related signaling with Proxies/Anchors

• Authentication between hosts and Proxies/Anchors

• Security

• Implementation

Implicit vs. Explicit Proxy/Anchor

Implicit Proxy Implicit Anchor

Host Host

Host Host

Host Host

Host Host

Explicit Proxy Explicit Anchor

Deployment: Proxy/Anchor resides on 3G/4G access networkAuthentication: Implicit with access authentication

Deployment: AnywhereAuthentication: Explicitly needed

TCPMPTCP

MPTCP TCPMPTCP

MPTCP MPTCP MPTCP

MPTCPMPTCP

MPTCP

MPTCP

MPTCP PROXY TCP

MPTCP Host MPTCP Host

SYN + MP_CAP

SYN-ACK

+ MP_CAP+ PROXY = 1

ACK + MP_CAP

MPTCP NN

SEEK_ADDR

ADD_ADDR+JOIN = 0

SYN + MP_JOIN

SYN-ACK + MP_JOIN

ACK + MP_JOIN

Implicit Proxy MPTCP-capable Session Initiator

MPTCP ANCHOR MPTCP

MPTCP Host MPTCP Host

SYN + MP_CAP

SYN-ACK + MP_CAP

ACK + MP_CAP

MPTCP NN

SEEK_ADDR

ADD_ADDR +JOIN = 0+ Addr_ID = 255

SYN + MP_JOIN, Addr_ID=X

SYN-ACK+MP_JOIN, Addr_ID=Y

ACK + MP_JOIN

Implicit Anchor MPTCP-capable Session Initiator

SEEK_ADDR

ADD_ADDR +JOIN = 0+ Addr_ID = 255

SYN + MP_JOIN, Addr_ID=X+ ANCHOR = 1

SYN-ACK+MP_JOIN, Addr_ID=Y

ACK + MP_JOIN

ANCHOR ?

ANCHOR ?

PROXY ?

PROXY

MPTCP Host MPTCP Host

SYN + MP_CAP

SYN-ACK

+MP_CAP +PROXY=1

ACK + MP_CAP

MPTCP NN

Implicit Proxy Chains MPTCP NN

PROXY

MPTCP Host MPTCP Host

SYN

SYN-ACK + MP_CAP

ACK

MPTCP NN MPTCP NN+ MP_CAP

+ PROXY=1

+ MP_CAP

PROXY ?

MPTCP Host MPTCP Host

SYN

SYN-ACK

ACK

MPTCP NN MPTCP NN+ MP_CAP

+ PROXY=1 +MP_CAP

+PROXY=1

Explicit signaling: Authentication + Peer’s IP address/PortNo

1. In-band MPTCP signaling: No extensible authentication possible dismissed

2. Out-of-band MPTCP signaling: HTTPS? IPsec? Beyond scope of MPTCP? not

considered

3. Authentication via pre-shared keys:32-bit host ID ++ MPTCP key derived from pre-shared keys ++ Peer’s IP/Port = ~40B (IPv6)

4. External signaling protocol:Host + NN establish MPTCP key, host sends peer’s

IP/port

5. External protocol for signaling & traffic: Transparent to MPTCP not considered

Explicit Proxy/Anchor

MPTCP PROXY TCP

MPTCP Host MPTCP Host

SYN + MP_CAP (keyA)

ACK + FWD_ADDR(IP, Prt)

MPTCP NN

SYN + MP_JOIN

SYN-ACK + MP_JOIN

ACK + MP_JOIN

Explicit Proxy Authentication via Pre-Shared Keys

SYN-ACK + MP_CAP (keyN)

SYN + MP_CAP(keyA) + ANCHOR = 1

SYN-ACK

ACK + MP_CAP() + PROXY = 1 ACK

4-wayhandshake

3-wayhandshake

MPTCP ANCHOR MPTCP

MPTCP Host MPTCP Host

SYN + MP_CAP (keyA)

ACK + FWD_ADDR(IP, Prt)

MPTCP NN

Explicit Anchor Authentication via Pre-Shared Keys

SYN-ACK + MP_CAP (keyN)

SYN + MP_CAP(keyA) + ANCHOR = 1

SYN-ACK + MP_CAP(keyB)

ACK + MP_CAP(keyB) + ANCHOR = 1ACK + MP_CAP(keyA, keyB)

SYN + MP_JOIN, Addr_ID=X

SYN-ACK+MP_JOIN, Addr_ID=Y

ACK + MP_JOIN

SYN + MP_JOIN, Addr_ID=X+ ANCHOR = 1

SYN-ACK+MP_JOIN, Addr_ID=Y

ACK + MP_JOIN

4-wayhandshake

3-wayhandshake

PROXY

Chain of Explicit Anchor/Proxy + Implicit ProxyAuthentication via Pre-Shared Keys

ANCHOR

MPTCP Host MPTCP Host

SYN + MP_CAP (keyA)

ACK + FWD_ADDR(IP, Prt)

ExplicitMPTCP NN

SYN-ACK + MP_CAP (keyEN)

SYN + MP_CAP(keyA) + ANCHOR = 1

+ MP_CAP(keyIN)+ PROXY = 1

ACK + MP_CAP(keyIN)+ PROXY = 1 + ANCHOR = 1 ACK + MP_CAP(keyA, keyIN)

ImplicitMPTCP NN

SYN-ACK

SEEK_ADDR

ADD_ADDR, Addr_ID = X+JOIN = 0

ADD_ADDR, Addr_ID = 255+JOIN = 0

4-wayhand

shake3-wayhandshake

Security - Explicit Proxy/Anchor

Security problem in absence of proper authentication: Distributed-DoS attacker uses proxy to hide its IP address

Attacker Victim

IP_SRC = ATTACKIP_DST = Proxy

IP_SRC = ProxyIP_DST = VICTIM

MPTCP NN

MPTCP Host MPTCP HostMPTCP Anchor

Simultaneous Mobility with (Implicit) Anchor

Traffic

SYN + MP_JOIN

TCP RST

SYN + MP_JOIN

TCP RST

SYN + MP_JOIN

SYN + MP_JOIN

Caches SRC IP

TCP RSTCaches SRC

IP

TCP RST

SYN + MP_JOIN

SYN-ACK + MP_JOIN SYN-ACK + MP_JOIN

Proxy Realization

Proxy creates logical MPTCP – TCP split connection

Large number of connections: Minimize cost-per-connection

• Minimize cost if only one path Design implications !

• Minimize buffer for multipath Design implications !

Cost-vs-Feature Tradeoff

• Mobility only Simple, low-cost implementation

• Multipath Higher performance at higher price

MPTCP Re-Charter Proposal

1. Proxies & Anchors

2. Mobility