Add GLBP info

source/_posts/2015-03-05-bizarre-packet-filtering-on-ovh-kimsufi-server.markdown

@@ -18,9 +18,14 @@ Analysis of the issue
 =====================
 
 This machine is on a network whose default router
-is `5.39.82.254` (`vss-gw-6k.fr.eu`). This router
-appears to answer ARP requests with two different MAC
-addresses: `00:07:b4:00:01:01` and `00:07:b4:00:01:02`.
+is `5.39.82.254` (`vss-gw-6k.fr.eu`).
+
+As far as I was able to determine, this is a virtual
+router, load balanced using [GLBP](http://www.freeccnastudyguide.com/study-guides/ccna/ch14/vrrp-hsrp-glbp/) .
+The two actual routers are:
+
+  * `vss-9b-6k.fr.eu`, MAC address `00:07:b4:00:01:01`
+  * `vss-9a-6k.fr.eu`, MAC address `00:07:b4:00:01:02`
 
 When attempting to establish an SSH connection from the outside
 to that machine, the first data packet in the connection
@@ -63,3 +68,7 @@ and all analysis elements in my possession have been conveyed to them,
 to no avail so far: the machine has been essentially unusable for the
 past two months and counting.
 
+Acknowledgements
+================
+
+Thanks to Pierre Beyssac for hinting at GLBP.