some time ago i’ve written a post about displaying live traffic that is going throught the router. also, i covered how it can be split based on autonomous system (with some sorting capabilities built in), thanks to Flexible NetFlow. recently, Flexible NetFlow was extended to use NBAR capabilities, and with that we have new options to sort traffic by application. with slightly modified flow record snippet, we can collect also the application name: ...
…hit me again (in a positive way). i was experimenting in my lab and wanted to define a lot of queues (and i mean a lot of them) in ALTQ. unfortunately, very quickly during parsing of pf.conf pfctl barked out following information: pfctl: DIOCADDALTQ: Cannot allocate memory to overcome the problem, you only need to modify those three files: /usr/include/altq/altq_hfsc.h /usr/src/sbin/pfctl/missing/altq/altq_hfsc.h /usr/src/sys/contrib/altq/altq/altq_hfsc.h where #define HFSC_MAX_CLASSES 64 is defined - to requested value. then rebuild the kernel and everything should work as expected. ...
working remotely on Windows via Remote Desktop if you’re hanging off GRPS or 3G connectivity somewhere in the mountains (for example) isn’t optimal. as I had to access some such servers remotely. you can find cygwin useful (there’s also VanDyke V-Shell, a bit pricey and for non-commercial use). cygwin package installs UNIX environment, and that - yes - may include OpenSSH plus some tools (like scp for example) you just need to download, and then run installation, selecting cygrunsrv and openssh. if you’re done - you just need to bootstrap SSH server and then start service responsible for SSH. ...
long, long time ago, playing with BGP was reserved for secret group of people, that somewhat alike Lems Trurl and Klapaucjusz were laughing from mere mortals but didn’t share the knowledge. then, a lot of things changed, trainings, certifications appeared, and then bootcamps and finally massive, open-for-all intro courses. and now, BGP is everywhere and is configured by anyone - you’ll find typical home wives running it as well, as without it they couldn’t upload new contact via bluetooth it seems. ...
i was stubborn - and while from the very first moment we’ve had a lot of challenges with the hotel infrastructure, i was able to run xTR routers during last PLNOG for LISP. no, it’s not about programming Cisco routers with LISP, but about new concept of Location/ID Split, that is new concept enabling you to treat traffic engineering in internet differently. in short - we still serve traffic like we always did (backward compatibility), but by assigning users and companies IPv4 and IPv6 addressing from special pools, we can treat this traffic in a different manner. LISP is de facto overlay network concept. this itself is nothing revolutionary, but on the other hand - it’s first such network that got wide adoption in world-wide internet. why would you like to use LISP? apart from ability to conserve IP addresses, LISP gives you ability to do traffic engineering without use of BGP or involving third parties. and in effect, adopting it may mean less FIB space needed on core internet routers. ...
if you’re peering with somebody else using one of available IXPs, prediction of traffic flow changes and optimization of paid services is crucial for proper traffic engineering. one of the more popular and easier tools, that is able to visualize traffic exchanged between ASes is AS-Stats. to properly doing its work, AS-Stats needs proper link definition in knownlinks file. NetFlow probes exported to collector will contain only the id and AS-Stats needs to match it. example file itself for my installation is simple: ...
it seems that more and more things are landing in our homes. couple of people that created nTop project with cooperation with Intel, built a device driver for Linux that can forward traffic using Intel X520 directly with 32 thousands of rules applied. 32 thousands is quite a number to serve real-life aggregation or core router, but at the same time it’s more than needed to serve as home firewall. similar things were done in the past in NVidia nForce chipset. ...
those of you frequently visiting my home site noticed that it wasn’t available for some time. unfortunately, that’s because of interesting RAID 5 failure in my server that hosts also my web page. FreeBSD relentlessly tried to serve web traffic from filesystem that was failing apart because of hardware problems, but then, 30 minutes after first failure, second hard disk failed in the same array! temperature was finely tuned, but it seems that after 5 years of continous work they had to fail. if anyone’s interested those were identical Seagate HDDs. ...
if you haven’t seen my practical demonstration at SecureCON 2007, you can see extended version on this thursday - i’ll be visiting AGH in Cracow at 7:45pm to do “show & tell” session as part of netWork sessions. session will be extended as we’ll have more time. photos can be found here and more information about the session itself can be found here.
i came back yesterday from Brussels and today at 5:30am the verdict came in - definitely “PASS” :) so… let me share some advice and tips for those of you preparing to take CCIE SP practical exam (without breaking NDA of course). first of all - if you have that luxury of training on any software version - please try to check with the current Cisco page and align. software is quite “specific”, and you may be hit with interesting behavior that may be a little bit different from mainline versions. in the era of simulators and emulators building your own lab replica should be easy. but you may be kicked in the ass by making wrong assumptions about specific software versions. ...