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The monkeysphere isn't the only project intending to implement a PKI
problems.
While ultimately contributing a patch to
-[OpenSSH](http://openssh.com/) (or any
+[OpenSSH](http://openssh.com/) (or
+[any](http://mina.apache.org/sshd/)
[free](http://www.chiark.greenend.org.uk/~sgtatham/putty/)
[SSH](http://www.lysator.liu.se/~nisse/lsh/)
[implementation](http://matt.ucc.asn.au/dropbear/dropbear.html)) is
* This client won't help if you are connecting to machines behind
firewalls, on NAT'ed LANs, with source IP filtering, or otherwise
- in a restricted network state.
+ in a restricted network state, because the notaries won't be able
+ to reach it.
* There is still a question of why you should trust these particular
notaries during your verification. Who are the notaries? How
* It doesn't provide any mechanism for key rotation or revocation:
Perspectives won't help you if you need to re-key your machine.
+ * The most common threat which Perspectives protects against (a
+ narrow MITM attack, e.g. the attacker controls your gateway) often
+ coincides with the ability of the attacker to filter arbitrary
+ traffic to your node. But in this case, the attacker could filter
+ out your traffic to the notaries (or the responses from the
+ notaries). Such filtering (rejecting unknown UDP traffic, as
+ Perspectives appears to use UDP port 15217) is unfortunately
+ common, particuarly on public networks, even when the gateway is
+ not malicious. This reduces the utility of the Perspectives
+ approach.
+
## OpenSSH with X.509v3 certificates ##
Roumen Petrov [maintains a patch to OpenSSH that works with the X.509