Open Source advantage

Consider this bug report for iTerm2, a terminal program for Mac OS X, where it panic’s Mac OS. The bug has been around for a while. There is no way you can actually check with Apple whether this issue has been resolved, is being worked on, will be resolved when, etc. That bug report by now contains a possible fix based on the Open Source version of the OS. In an open source OS this would be a) fixed by now by someone having the problem, b) probably be included in a release that has already shipped, and c) if not included, patchable in your local system by yourself.

The advantage of closed source is obviously blame allocation: It is their fault because I, the paying customer, say so. However, that is not much help on a thursday evening when struggling to make automated updates of 450 NanoStation M2’s work, with a laptop that crashes every hour.

DNS in a mixed VSat / 3G environment

In this mobile application we use a VSat (Internet over satellite link) for the heavy lifting and 3G as a fallback connection. One of the biggest issues with VSat is its latency of 700msecs up to 5000msecs, depending on the location of the satellite, and other factors. In today’s environment, with heavy dependence on DNS to provide content from different locations (hello, CDN providers!), DNS becomes a bottleneck on VSat systems.

This problem can be reduced at limited cost by doing DNS over 3G (when available). The downside to this is that availability of DNS servers changes heavily depending on the connections available. 3G is not generally available on rivers, so these DNS servers tend to arrive and disappear frequently.

Second, VSat tends to loose signal when turning too quickly, when moored in a deep lock or behind a building, or when crossing under a bridge. To provide Internet access as much as possible we automatically switch the default route to 3G when we loose signal, and switch back to VSat when reacquired. This switching again causes appearance and disappearance of DNS servers, but now also the DNS servers behind the long latency VSat link. Dropping information on timing of these DNS servers needs to be avoided to make sure that DNS servers reachable over 3G are preferred when they both come back.

With the unbound caching DNS server we’ve got a tool that allows us to modify several parameters:

  • add and remove DNS forward entries
  • flush DNS entries, whole zones, but also DNS resolver information
  • provide local subnets / precreated zones
  • increase the minimum TTL of a DNS entry from seconds to minutes to reduce requests
  • do pre-fetching of DNS entries
  • look at DNS resolution statistics of the running daemon

Many of these features will disagree with normal behaviour on the Internet, but given the audience on board, it is generally preferable to speed up name resolution. Adding host specific routing entries for the DNS servers, and using open DNS resolvers (Google and Level3) performance has improved considerably.

New Option modem

We were using the GTM382W UMTS Mini-PCI Express modem from Option. As that product has been discontinued, we have switched to the GTM661W modem, which is a half size Mini PCI Express modem, in combination with an extender plate to make it fit in existing slots.

Today we are going to a) figure out which 2 of the 7 serial ports on the USB device I need for PPP resp. control connections and b) check whether the modem still accepts all the commands we are using to interrogate the modem on the control connection hop over to this site.

One wonders why these companies go through the trouble of redesigning everything for every new modem they sell. New IDs, new port allocations, new packaging.

071 ICT Café

<a href="http://www omeprazole dr 20mg”>071 ICT logoTijdens het ICT Café van 071 ICT in december gaf AnyWi een korte presentatie over het project Internet op cruiseschepen. Het gebruik van iPads, tablets en smartphones wordt steeds belangrijker, ook op reis. Een goede internetverbinding is dan ook voor vele toeristen onmisbaar. Touroperators eisen steeds vaker dat cruisemaatschappijen internet aan boord leveren zoals men dat thuis gewend is. De meeste hotels bieden inmiddels gratis wifi aan hun gasten aan, maar op cruiseschepen is dit minder makkelijk te organiseren.

In zijn presentatie De iPad als reisgids. Een probleem voor Cruisemaatschappijen! vertelde Nick Hibma over de complexiteit van mobiel internet en de problemen waar cruisemaatschappijen mee geconfronteerd worden zoals:

  • hoge kosten
  • onbetrouwbare verbindingen
  • ontevreden gasten

AnyWi werkt momenteel aan een oplossing voor deze problemen.

071 ICT is hét platform voor de Leidse ICT-branche en ICT-professionals. Het motto van 071 ICT is: Vernieuwing door ICT. 071 ICT organiseert vier keer per jaar netwerkbijeenkomsten. Naast de presentatie van AnyWi was er tijdens de laatste bijeenkomst ook een presentatie over CrowdRoaming, een project dat toeristen op een innovatieve manier probeert te voorzien van internet via de databundels van de lokale bevolking.



Van 18-10 t/m 22-10 was de jaarlijkse European BSD Conference, in Warsaw, PL. 200 mensen betrokken bij en gebruikers van de verschillende BSD smaken kwamen bijeen om ideeën uit te wisselen, cursussen te volgen en meer te leren over FreeBSD, NetBSD, OpenBSD, DragonFly BSD, etc. AnyWi maakt op veel machines gebruik van FreeBSD en is als src committer ook betrokken bij de verdere ontwikkeling daarvan.

Tijdens de conferentie waren er volop mogelijkheden om on-the-spot bugs op te lossen, met gelijkgezinden oplossingen voor prangende vragen te bespreken, of gewoon bij te praten en ideeën op te doen.

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