From Computerworld

Wednesday, 21 April, 2004

Bogon filtering blocks some sites in NZ

Paul Brislen, Auckland

JetStream users around the country may be unable to access some of their favourite websites because the IP addresses they are assigned are being blocked.

Several users have reported being unable to access a number of sites, including CNN , Google and parts of Yahoo's portal among others. Newsgroups and mailing lists like nz.comp have been abuzz with speculation as to why and how this is happening.

"It seems that some ISP's are blocking traffic to user with IP addresses in that range", wrote one early poster.

Telecom spokeswoman Katrina King says the problem is related to the IP address block Telecom has been assigned. King says IP addresses in the 222.x.x.x range are still being treated as "bogon" by some website operators.

A bogon IP address is one that has not yet been assigned - many ISPs filter out all incoming traffic from bogon addresses because they are perceived to have no legitimate purpose. However, if an address block is assigned it is up to the individual ISPs to ensure their filters are updated as well. If they aren't, the result is end users who cannot access certain websites.

King says all Telecom can do is talk to those sites.

"If users notify us they're having problems, all we can do is notify those sites and open up access to those addresses."

King says the problem will affect JetStream customers in particular, regardless of which ISP they use.

Auckland-based ISP Orcon Internet says the problem has been going on for some time, and all customers can do is contact their ISP with the name of site they're unable to view. Managing director Seeby Woodhouse says there isn't much else anyone can do.

"The issue is not so much Telecom in that respect, it's these other sites have not sussed out that those addresses are now valid."

IP addresses are assigned by the Internet Assigned Numbers Authority (IANA)or one of its authorised registries, in this case the Asia Pacific Network Information Centre APNIC in Brisbane.

Telecom advises users to contact their ISP helpdesk with the name of the site they are unable to access and their IP address, if they know it.

Users with dynamically allocated IP addresses can reboot their connections to try to change their address. Telecom believes only the 222.x.x.x range is affected, however Computerworld has been contacted by at least one user whose IP address was in the 219.x.x.x range and they were also unable to access a number of websites. Rebooting the DSL modem gave them a new address and the sites were immediately available again.

APNIC was not immediately available for comment.

Related links

Bogon Filtering - Wikipedia definition

Team Cymru Bogon Reference Page