Secure and Dependable Clock Synchronization on Next-Generation Networks

Secure and dependable clock synchronization is an essential prerequisite for many industries with applications in finance, telecommunication, electric power production and distribution, or environmental monitoring.

Current best practice to achieve large-scale clock synchronization relies on global navigation satellite systems (GNSSes) at the considerable risk of being exposed to outages, malfunction, or attacks against availability and accuracy. Natural disasters like solar superstorms also have the potential to hit and severely impact GNSSes.

It is therefore all too apparent that clock synchronization solely based on GNSSes as global reference clocks does not fulfill fundamental dependability requirements for systems that serve indispensable functionalities in our society. Facing these concerns, governments have issued mandates to protect critical infrastructure services from disruption to GNSS services, including a 2020 US Executive Order. Operators and equipment manufacturers are encouraged to intensify research and development of alternative technologies in this space.

Aiming to join these efforts, we are proposing G-SINC: a novel global, Byzantine fault-tolerant clock synchronization approach that does not place trust in any single entity and is able to tolerate a fraction of faulty entities while still maintaining accurate synchronization on a global scale among otherwise sovereign network topologies. G-SINC can be implemented as a fully backward compatible active standby solution for existing time synchronization deployments.

This is achieved by building on the solid body of fault-tolerant clock synchronization research dating all the way back to the 1980s and the SCION Internet architecture providing required resilience and security properties at the network level as an intrinsic consequence of its underlying design principles. Besides the possibility to use multiple distinct network paths in parallel for significantly improved fault-tolerance, we highlight the fact that SCION paths are reversible and therefore symmetric. Hence, they help to increase time synchronization precision compared to clock offset measurements over the often asymmetric paths in today’s Internet.

We are currently building out the first end-to-end implementation of G-SINC which is contained in this repository.

Publication

G-SINC: Global Synchronization Infrastructure for Network Clocks. Marc Frei, Jonghoon Kwon, Seyedali Tabaeiaghdaei, Marc Wyss, Christoph Lenzen, and Adrian Perrig. In Proceedings of the Symposium on Reliable Distributed Systems (SRDS) 2022. [pdf], [doi], [arXiv]

Running a simple IP-based server

Reference platform: Ubuntu 22.04 LTS, Go 1.23.1; see below.

cd ~
git clone https://github.com/marcfrei/scion-time.git

cd ~/scion-time
go build timeservice.go timeservicex.go

sudo ~/scion-time/timeservice server -verbose -config testnet/test-server.toml

Querying an IP-based server

In an additional session:

~/scion-time/timeservice tool -verbose -local 0-0,0.0.0.0 -remote 0-0,127.0.0.1:123

Querying an IP-based server with Network Time Security (NTS)

In an additional session:

~/scion-time/timeservice tool -verbose -local 0-0,0.0.0.0 -remote 0-0,127.0.0.1:4460 -auth nts -ntske-insecure-skip-verify

Installing prerequisites for a SCION test environment

Reference platform: Ubuntu 22.04 LTS, Go 1.23.1

sudo apt-get update
sudo apt-get install -y build-essential python3-pip supervisor
pip3 install plumbum toml supervisor-wildcards

On x86-64:

sudo rm -rf /usr/local/go
curl -LO https://golang.org/dl/go1.23.1.linux-amd64.tar.gz
echo "49bbb517cfa9eee677e1e7897f7cf9cfdbcf49e05f61984a2789136de359f9bd go1.23.1.linux-amd64.tar.gz" | sha256sum -c
sudo tar -C /usr/local -xzf go1.23.1.linux-amd64.tar.gz
rm go1.23.1.linux-amd64.tar.gz
echo >> .bash_profile
echo 'export PATH=$PATH:/usr/local/go/bin' >> .bash_profile
source ~/.bash_profile
go version

On ARM64:

sudo rm -rf /usr/local/go
curl -LO https://golang.org/dl/go1.23.1.linux-arm64.tar.gz
echo "faec7f7f8ae53fda0f3d408f52182d942cc89ef5b7d3d9f23ff117437d4b2d2f go1.23.1.linux-arm64.tar.gz" | sha256sum -c
sudo tar -C /usr/local -xzf go1.23.1.linux-arm64.tar.gz
rm go1.23.1.linux-arm64.tar.gz
echo >> .bash_profile
echo 'export PATH=$PATH:/usr/local/go/bin' >> .bash_profile
source ~/.bash_profile
go version

Setting up a SCION test environment

cd ~
git clone https://github.com/scionproto/scion.git

cd ~/scion
git checkout v0.11.0
go build -o ./bin/ ./control/cmd/control
go build -o ./bin/ ./daemon/cmd/daemon
go build -o ./bin/ ./dispatcher/cmd/dispatcher
go build -o ./bin/ ./router/cmd/router
go build -o ./bin/ ./scion/cmd/scion
go build -o ./bin/ ./scion-pki/cmd/scion-pki

cd ~
git clone https://github.com/marcfrei/scion-time.git

cd ~/scion-time
go build timeservice.go timeservicex.go

Starting the SCION test network

export SCION_BIN=~/scion/bin
cd ~/scion-time/testnet

rm -rf logs
./scion-topo-gen-crypto.sh
./testnet-up.sh

./supervisor/supervisor.sh reload && sleep 1
./supervisor/supervisor.sh start all

Running the servers

In session no. 1, run server at 1-ff00:0:111,10.1.1.11:10123:

cd ~/scion-time
sudo ip netns exec netns0 ./timeservice server -verbose -config testnet/gen-eh/ASff00_0_111/ts1-ff00_0_111-1.toml

In session no. 2, run server at 1-ff00:0:112,10.1.1.12:10123:

cd ~/scion-time
sudo ip netns exec netns1 ./timeservice server -verbose -config testnet/gen-eh/ASff00_0_112/ts1-ff00_0_112-1.toml

Querying SCION-based servers

In an additional session, query server at 1-ff00:0:111,10.1.1.11:10123 from 1-ff00:0:112,10.1.1.12:

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -daemon 10.1.1.12:30255 -local 1-ff00:0:112,10.1.1.12 -remote 1-ff00:0:111,10.1.1.11:10123

Or query server at 1-ff00:0:112,10.1.1.12:10123 from 1-ff00:0:111,10.1.1.11:

sudo ip netns exec netns0 ~/scion-time/timeservice tool -verbose -daemon 10.1.1.11:30255 -local 1-ff00:0:111,10.1.1.11 -remote 1-ff00:0:112,10.1.1.12:10123

Querying a SCION-based server with SCION Packet Authenticator Option (SPAO)

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -daemon 10.1.1.12:30255 -local 1-ff00:0:112,10.1.1.12 -remote 1-ff00:0:111,10.1.1.11:10123 -auth spao

Querying a SCION-based server with Network Time Security (NTS)

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -daemon 10.1.1.12:30255 -local 1-ff00:0:112,10.1.1.12 -remote 1-ff00:0:111,10.1.1.11:14460 -auth nts -ntske-insecure-skip-verify

Querying a SCION-based server with SPAO and NTS

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -daemon 10.1.1.12:30255 -local 1-ff00:0:112,10.1.1.12 -remote 1-ff00:0:111,10.1.1.11:14460 -auth spao,nts -ntske-insecure-skip-verify

Querying a SCION-based server via IP

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -local 0-0,10.1.1.12 -remote 0-0,10.1.1.11:123

Querying a SCION-based server via IP with NTS

sudo ip netns exec netns1 ~/scion-time/timeservice tool -verbose -local 0-0,10.1.1.12 -remote 0-0,10.1.1.11:4460 -auth nts -ntske-insecure-skip-verify

Synchronizing with a SCION-based server

In session no. 1, run server at 1-ff00:0:111,10.1.1.11:10123:

cd ~/scion-time
sudo ip netns exec netns0 ./timeservice server -verbose -config testnet/gen-eh/ASff00_0_111/ts1-ff00_0_111-1.toml

And in session no. 2, synchronize node 1-ff00:0:112,10.1.1.12 with server at 1-ff00:0:111,10.1.1.11:10123:

cd ~/scion-time
sudo ip netns exec netns1 ./timeservice client -verbose -config testnet/gen-eh/ASff00_0_112/test-client.toml

Stopping the SCION test network

export SCION_BIN=~/scion/bin
cd ~/scion-time/testnet

./supervisor/supervisor.sh stop all