Wednesday, May 14, 2008

Network devices that lie

Do some network devices lie about their config, or are they just talking past each other?

One of my tasks recently has been to start integrating the networks of two companies, because one of the companies bought the other.

At my end you would have guessed already that anything exposed to the Internet would be running OpenBSD, while at the other end they were strangely attached to products from a certain software marketer based in the north-western part of the USA. But for the IPSEC part, they had decided that a certain proprietary "Internet Security Appliance" would fill their needs, and at each of their locations they had identical appliances running for "VPN" purposes.

Therein lies a story. After a few working days of debugging my way to an almost working configuration, my main conclusion is, that it is quite likely that proprietary security appliance lies. That is, it will let its administrator choose a wide range of very specific configuation options, but will actually override them, at least if the device at the other end does not do the "I'm one of your kind" secret handshake.

Here's what it looks like in the logs on the OpenBSD end, the part that is supposed to be a negotiation but actually isn't and the options on the OpenBSD side matched the options given in the screendumps of the other side's GUI that I had to work with:
May 13 14:00:28 delilah isakmpd[13547]: attribute_unacceptable: 
May 13 14:00:28 delilah isakmpd[13547]: attribute_unacceptable: 
HASH_ALGORITHM: got MD5, expected SHA

and so on, through the various options, each time expecting what matched the screendumps, getting something else entirely, up until the inevitable
May 13 14:00:28 delilah isakmpd[13547]: 
message_negotiate_sa: no compatible proposal found

or as they say elsewhere, Do not pass GO.

Moving on from there to actual tunnel setup reveals troublesome vendor IDs and other strangeness. This could very well be an attempt at vendor lock-in, but then the conventional wisdom anyway seems to be that the only way to set up a VPN is to have identical devices at every endpoint. There is no good reason why it should be like that, but I may be discovering the less good ones.

The main reason I'm not naming names or stating flat-out that "this device lies about its configuration" is that my analysis is not complete yet. If you have data you want to share with me on this or similar experiences, I would love to hear from you, at It's likely I'll write a followup based on what I hear and what happens.

During my silent period blogging wise, some notable events did occur, and I may return to them in later posts.

UKUUG Spring 2008
In late March I went to Birmingham to attend the UKUUG Sping 2008 conference - with a PF tutorial much like the one in Riga in February and a refreshed malware talk. A number of very good talks, and a number of Perl Mongers there, notably Barbie, who told me about his "Understanding Malware" talk that actually overlaps quite a bit with my paper. The social parts were good too, and yes, in Birmingham it is possible to find Real Ale.

BSD Magazine #1 is out
Not too long after the UKUUG Spring Conference, the first issue of BSD Magazine was published. Readers of this blog may find one article to be slightly familiar, but there's a nice selection of articles and reviews, covering all the BSD systems and a wide range of topics. And I should mention, they are looking for articles for upcoming issues.

OpenBSD 4.3 is out
OpenBSD 4.3 was released on schedule on May 1st, and as usual those who pre-ordered got their copies early. As always, exciting new stuff as well as a number of incremental improvements. There's interesting stuff happening post-4.3 as well, watch undeadly for updates.

Next up: FOSS Aalborg, June 4th
Our Danish friends are kind enough to give us yet another excuse to come visit. A group of BSD and Linux people have been hosting good conferences in Copenhagen for years, last year's EuroBSDCon being one.

This time it's Aalborg's turn, with a one day conference on June 4th. Yours truly will be on the speaker list. I hope to see you there, I will be bringing a small stack of books.

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