This describes how to configure an ipsec VPN in an AWS VPC with a customer who does not allow RFC-1918 (private) IP addresses in the VPC subnet.
The basic idea is to expose a single host in the VPN using a /32
subnet of the VPN public IP. We can restrict each client peer to a specific port on that host and use port forwarding to connect them to internal hosts on private subnets in the VPC. So we can support multiple clients, and each client sees only a single host (with a public IP) and can access a single client specific port on that host.
The following applies to Ubuntu 14.04 and Strongswan 5.1.2. For purposes of discussion we have two clients. All public IPs are invalid examples. First, clientA with peer public IP 165.{A}.22.101 and an internal host with public IP 165.{A}.22.102. We will restrict clientA to port 2575. Second, clientB with peer public IP 180.{B}.89.101 and an internal host with public IP 180.{B}.89.102. We will restrict clientB to port 2576.
We create an EC2 instance in a VPC with CIDR 10.0.0.0/16
and place it in a public subnet with CIDR
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Sometimes you want to secure local traffic in a private subnet for compliance reasons, e.g. HIPAA requires data in-transit to be encrypted. This can be done at the application level if the application supports SSL, but it can also be done independent of the application using IPsec transport layer encryption.
In this example we have an AWS VPC with three Ubuntu 14.04 database instances in a private subnet running a mongodb replicaset with three members. We want to encrypt all mongodb traffic between replicaset members and between other client instances in the VPC and the mongodb instances - and we won’t use mongodb SSL support.
The mad-hacking site has a good discussion of IPsec, racoon and setkey.
First install ipsec-tools and racoon on each instance: sudo apt-get install ipsec-tools racoon
.
Create a pre-shared key file for use with ISAKMP. We are using the wildcard *
to match all hosts, so all instances are using the same key. Generate this file once and install the same file on all instances:
Generate the file with a random key:
user@host$ echo "* " $(openssl rand -base64 48
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This is an Swift class to allow KVO observing using Swift closures, useable from a Swift class that does not subclass NSObject
.
From Swift, create a KeyValueObserver
instance with the object being observed, the key path to observe and a closure to be called. As long as this instance remains alive, observations will be reported to the closure. To remove the observer, release the KeyValueObserver
instance (so assign it to an optional so you can assign that to nil
to release it).
let button = UIButton() var kvo: KeyValueObserver? = KeyValueObserver(source: button, keyPath: "selected", options: .New) { (kvo, change) in NSLog("observing %@ %@", kvo.keyPath, change) } button.selected = true button.selected = false kvo = nil button.selected = true
You can save the observer in an...
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