Sometimes Verizon FiOS customers have problems browsing certain websites. Perhaps the sites are being blocked? Here are some ideas about diagnosing the problem that I've found working as a sysadmin. I hope they help...
On the website/sysadmin end, if I want to check if my servers are blocking a user at a particular IP, I run through this checklist: I check that my load balancers and web servers are up, have network connectivity, have sane routing tables, are running their web server listening on port 80. I ping them from an external IP, like from the open wifi next door. I try browsing web content on port 80 (HTTP) and on port 443 (HTTPS). I check the domain's DNS record global propagation using some external sites. On the Linux servers hosting the site, I check that no iptables firewall rules and PAM configuration are set to block anyone. I'm pretty sure that kernel bogon packet filtering was no longer an issue after 2011. When all those things check out okay, I'm pretty sure the site is available to most of the planet for browsing.
So what about the Verizon FiOS end of the connection? If a site seems blocked, here are some things users can check:
Do a hostname lookup for the website. You should receive one or more IP addresses. Do the same lookup on a public DNS server. Do the IP addresses match? Are all the IP addresses pingable? If the website servers respond, then they are at least answering ICMP echo request packets. See if typing the site's URL in your browser results in either the site webpage or a timeout message. If the page doesn't show up, try browsing the site's port 443 SSL service by typing "https" in the site's URL. If Verizon has given you some sort of content filtering software to run on your computer, check to see if it is blocking either the site or a keyword. If you can log in to your Verizon FiOS router, check to see if it has a content or keyword filtering feature enabled. Sometimes these things are updated remotely by the ISP. Some routers may offer logs of the sites blocked. If you have an online Verizon FiOS customer account that offers some sort of control panel, check that for any filtering options enabled.
If you are more of a power user, you might use a TCP traceroute tool (lft) to reveal where along the path your port 80 packets are getting dropped. There are scanning tools (nmap) to see if ports 80 and 443 on the website are seen as open. There are commandline browsing tools (wget) to examine any response on port 80.
The most useful thing I've found is to do web searches for the problems I'm having; If I confront a problem, often it turns out dozens of others have already encountered it as well.
regards,
Peter
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