Transparent Encryption (stable/beta)¶

Generate & import the PSK¶

First create a Kubernetes secret for the IPsec keys to be stored. This will generate the necessary IPsec keys which will be distributed as a Kubernetes secret called cilium-ipsec-keys. In this example we use GMC-128-AES, but any of the supported Linux algorithms may be used. To generate use the following

$ kubectl create -n kube-system secret generic cilium-ipsec-keys \
    --from-literal=keys="3 rfc4106(gcm(aes)) $(echo $(dd if=/dev/urandom count=20 bs=1 2> /dev/null| xxd -p -c 64)) 128"

The secret can be displayed with kubectl -n kube-system get secret and will be listed as ‘cilium-ipsec-keys’.

$ kubectl -n kube-system get secrets cilium-ipsec-keys
NAME                TYPE     DATA   AGE
cilium-ipsec-keys   Opaque   1      176m

Enable Encryption in Cilium¶

Setup helm repository:

helm repo add cilium https://helm.cilium.io/

Deploy Cilium release via Helm:

helm install cilium cilium/cilium --version 1.7.4 \
  --namespace kube-system \
  --set global.encryption.enabled=true \
  --set global.encryption.nodeEncryption=false

At this point the Cilium managed nodes will be using IPsec for all traffic. For further information on Cilium’s transparent encryption, see Architecture.

--set global.encryption.interface=ethX

[...]
--set global.encryption.enabled=true \
--set global.encryption.nodeEncryption=true

Validate the Setup¶

Run a bash shell in one of the Cilium pods with kubectl -n kube-system exec -ti cilium-7cpsm -- bash and execute the following commands:

1. Install tcpdump

apt-get update
apt-get -y install tcpdump

2. Check that traffic is encrypted:

tcpdump -n -i cilium_vxlan
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on cilium_vxlan, link-type EN10MB (Ethernet), capture size 262144 bytes
15:16:21.626416 IP 10.60.1.1 > 10.60.0.1: ESP(spi=0x00000001,seq=0x57e2), length 180
15:16:21.626473 IP 10.60.1.1 > 10.60.0.1: ESP(spi=0x00000001,seq=0x57e3), length 180
15:16:21.627167 IP 10.60.0.1 > 10.60.1.1: ESP(spi=0x00000001,seq=0x579d), length 100
15:16:21.627296 IP 10.60.0.1 > 10.60.1.1: ESP(spi=0x00000001,seq=0x579e), length 100
15:16:21.627523 IP 10.60.0.1 > 10.60.1.1: ESP(spi=0x00000001,seq=0x579f), length 180
15:16:21.627699 IP 10.60.1.1 > 10.60.0.1: ESP(spi=0x00000001,seq=0x57e4), length 100
15:16:21.628408 IP 10.60.1.1 > 10.60.0.1: ESP(spi=0x00000001,seq=0x57e5), length 100

Key Rotation¶

To replace cilium-ipsec-keys secret with a new keys,

KEYID=$(kubectl get secret -n kube-system cilium-ipsec-keys -o yaml|grep keys: | awk '{print $2}' | base64 -d | awk '{print $1}')
if [[ $KEYID -gt 15 ]]; then KEYID=0; fi
data=$(echo "{\"stringData\":{\"keys\":\"$((($KEYID+1))) "rfc4106\(gcm\(aes\)\)" $(echo $(dd if=/dev/urandom count=20 bs=1 2> /dev/null| xxd -p -c 64)) 128\"}}")
kubectl patch secret -n kube-system cilium-ipsec-keys -p="${data}" -v=1

Then restart cilium agents to transition to the new key. During transition the new and old keys will be in use. The cilium agent keeps per endpoint data on which key is used by each endpoint and will use the correct key if either side has not yet been updated. In this way encryption will work as new keys are rolled out.

The KEYID environment variable in the above example stores the current key ID used by Cilium. The key variable is a uint8 with value between 0-16 and should be monotonically increasing every re-key with a rollover from 16 to 0. The cilium agent will default to KEYID of zero if its not specified in the secret.

Troubleshooting¶

• Make sure that the Cilium pods have kvstore connectivity:

  cilium status
  KVStore:                Ok   etcd: 1/1 connected: http://127.0.0.1:31079 - 3.3.2 (Leader)
  [...]
  

• Check for level=warning and level=error messages in the Cilium log files

• Run a bash in a Cilium and validate the following:

  • Routing rules matching on fwmark:

    ip rule list
    1:      from all fwmark 0xd00/0xf00 lookup 200
    1:      from all fwmark 0xe00/0xf00 lookup 200
    [...]
    

  • Content of routing table 200

    ip route list table 200
    local 10.60.0.0/24 dev cilium_vxlan proto 50 scope host
    10.60.1.0/24 via 10.60.0.1 dev cilium_host
    

  • XFRM policy:

    ip xfrm p
    src 10.60.1.1/24 dst 10.60.0.1/24
            dir fwd priority 0
            mark 0xd00/0xf00
            tmpl src 10.60.1.1 dst 10.60.0.1
                    proto esp spi 0x00000001 reqid 1 mode tunnel
    src 10.60.1.1/24 dst 10.60.0.1/24
            dir in priority 0
            mark 0xd00/0xf00
            tmpl src 10.60.1.1 dst 10.60.0.1
                    proto esp spi 0x00000001 reqid 1 mode tunnel
    src 10.60.0.1/24 dst 10.60.1.1/24
            dir out priority 0
            mark 0xe00/0xf00
            tmpl src 10.60.0.1 dst 10.60.1.1
                    proto esp spi 0x00000001 reqid 1 mode tunnel
    

  • XFRM state:

    ip xfrm s
    src 10.60.0.1 dst 10.60.1.1
            proto esp spi 0x00000001 reqid 1 mode tunnel
            replay-window 0
            auth-trunc hmac(sha256) 0x6162636465666768696a6b6c6d6e6f70717273747576777a797a414243444546 96
            enc cbc(aes) 0x6162636465666768696a6b6c6d6e6f70717273747576777a797a414243444546
            anti-replay context: seq 0x0, oseq 0xe0c0, bitmap 0x00000000
            sel src 0.0.0.0/0 dst 0.0.0.0/0
    src 10.60.1.1 dst 10.60.0.1
            proto esp spi 0x00000001 reqid 1 mode tunnel
            replay-window 0
            auth-trunc hmac(sha256) 0x6162636465666768696a6b6c6d6e6f70717273747576777a797a414243444546 96
            enc cbc(aes) 0x6162636465666768696a6b6c6d6e6f70717273747576777a797a414243444546
            anti-replay context: seq 0x0, oseq 0x0, bitmap 0x00000000
            sel src 0.0.0.0/0 dst 0.0.0.0/0
    

Disabling Encryption¶

To disable the encryption, regenerate the YAML with the option global.encryption.enabled=false