Hurricane Electric’s Looking Glass and Route Server Utility

Hurricane Electric is proud to offer a number of free services.  We provide a dual-stack DNS management tool with dynamic DNS support, an IPv6 certification program used worldwide in 101 countries, an IPv6 Tunnel Broker currently supporting 75,000 user-created tunnels, and a newly released interactive programming service which has already delivered nearly 500,000 exercises since its inception.

One other service that you may have seen mentioned is Hurricane Electric’s Network Looking Glass.  In general, the looking glass allows you to examine network behavior like connectivity, path, and routing information from various vantage points in Hurricane Electric’s (awesome) network.  Looking glasses are commonly used for verifying routing between providers.

There are two ways to access Hurricane Electric’s looking glass.  The first is to telnet to our public route server at and the second option is to use the web interface available at  Our web-based looking glass utility is a unique PHP/Perl blend which was created in-house in Fremont, California.

Upon visiting, you’ll find a list of some of our routers at core locations and commands that you can run to a specified destination.  The “ping” command displays roundtrip time between the selected Hurricane Electric node and the specified IP address.  “Traceroute,” on the other hand, shows all router hops encountered in the path between the specified router and IP address. Also available through is the BGP Route command and IPv4/IPv6 BGP summaries which display Border Gateway Protocol route propagation information.

What reasons are there for using Hurricane Electric’s looking glass?  Besides offering transparency in how we operate our backbone infrastructure, you can evaluate to some degree how our network stacks up to your current provider.  Feel free to check out how well-connected Hurricane Electric is and how you might benefit from buying transit with us or by peering (write to and for more info).

In truth, a looking glass is more for network operators and ‘Net geeks who love everything about “pushing bits.”  The ping command allows us to see that a device is up and capable of returning packets and traceroute can help diagnose network routing issues while following a packet to its destination.  The BGP commands are a bit of a different story.

Border Gateway Protocol is a routing protocol similar to RIP, EIGRP, OSPF, and IS-IS, but is instead an exterior gateway protocol used to connect all the different autonomous systems (AS) across the Internet.  This allows ISPs to connect to each other and end-users to connect to more than one ISP, something known as multi-homing.

BGP keeps a table of IP network prefixes which announce connectivity between those ASes; the protocol then makes decisions based on this reachability information and on path and network policies.  Using the BGP Route command shows matching routes with status details; the BGP Summary (IPv4 and IPv6) commands show a limited view of the BGP routing table used for a given route in Hurricane Electric’s network.

So the Hurricane Electric looking glass can be very useful. If you change routing announcements, it’s possible to check that your routing changes were correctly deployed and that the “world” is seeing your network the way you planned.  You can utilize looking glasses to verify that your routes are propagating correctly across the Internet and to see whether any are “flapping” (when a destination network is advertised via one route then another in quick succession).  If we’re one of your upstream providers, you can make sure that we’re seeing your announced prefixes.  Troubleshooting, like checking for consistency across networks or for a filter change that might be blocking your routes, is also possible on looking glasses.

Visit to try out the utility and all its functions for yourself.  If you have any questions (or you’ve decided to pull the trigger on buying transit), be sure to send us an email.