Some IP addresses are being blocked when I try to access them from my Linode under Ubuntu 14.04.1. I discovered this when these sites were blocked via my VPN on Linode. I soon found out that this is VPN-independent, since I cannot access them directly from my Linode shell as well.

I CAN access these sites from other shells at other accounts I have, e.g., directly from a Caltech account as well as from my local Charter ISP (turning VPN off). E.g., I can test this under ssh-X with a browser like Firefox/Chrome, or with elinks, lynx, etc.

Out of 100's of sites I connect to via 2 PCs and 2 phones, there are less than half a dozen with this blocking problem, but these are pretty public sites, e.g.,
http://researchgate.net
https://www.aarpmedicareplans.com

I have checked numerous sites that test for blacklisted IPs, and I am on none of these 100 or so sites. These sites are not listed in any of my iptables, etc.

I have had this Linode at Fremont for over 4 years, with the same static IPv4 address.

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http://www.ingber.com

First check your IP(s) against the known black lists, assuming you're not in a spammers database, then contact the sites that are blocking your Linode IP and ask them why they are blocking it, then go from there.

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Either provide enough details for people to help, or sit back and listen to the crickets chirp.
Security thru obscurity is a myth - and really really annoying.

Hi. As I said, I have checked against balcklist sites, some that themselves check for 70-100 blacklists, and I got through just fine with none having my IP address. In the process, I also corrected one site that had an outdated blacklist site, for which I got a nice "thank you".

i did contact the sites -- the only way I could was to use email addresses in the whois database. I'll see where that goes ...

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http://www.ingber.com

Linode support is pretty busy, but they followed up a statement of that, followed with a request for more info. After looking at all the info, they too are surprised at this problem. I'll report back if there is any resolution.

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http://www.ingber.com

I tried the first one and can confirm it's blocked from my Linodes in 2 different data centers.

wget --spider http://researchgate.net
Spider mode enabled. Check if remote file exists.
--2014-12-30 19:40:14-- http://researchgate.net/
Resolving researchgate.net (researchgate.net)... 69.174.243.184
Connecting to researchgate.net (researchgate.net)|69.174.243.184|:80... failed: No route to host.

Then I tried the wget from my Desktop and it attempted 20 different 301 redirects before wget stopped. Oddly, it worked when I hit the site from my desktop in my Chrome browser.

The site's IP is clean here:
http://www.tcpiputils.com/browse/ip-add ... 74.243.184

diltonm:

Thanks. That's obviously a big help. I've flushed (and saved) my iptables to prove the problem is not there. Your comments should help support look elsewhere.

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http://www.ingber.com

Yeah, clearly a firewall issue somewhere...

From my linode

$ telnet researchgate.net 22
Trying 69.174.243.184...
Connected to researchgate.net.
Escape character is '^]'.
SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2

Protocol mismatch.
Connection closed by foreign host.
$ telnet researchgate.net 80
Trying 69.174.243.184...
telnet: connect to address 69.174.243.184: Connection refused

So something is blocking port 80 traffic but letting port 22 traffic through.

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Rgds
Stephen
(Linux user since kernel version 0.11)

Someone in Linode Support wrote me that he too has this problem on his Linode, but not other PCs, and he concludes that researchgate.net is blocking some Linode IPs.

I'm not too surprised. In the past I've caught a few Linode users trying to hack into my VPS. It's bound to come home to us ...

If I'm correct, I still have to explain why my Linode IP is not blacklisted. Perhaps some sites getting hacked do what a lot of us under similar circumstances -- we block ranges of IPs, and don't bother trying to get specific hackers' IPs blacklisted. In many cases, blacklisting hackers' IPs is a waste of time as they just change IP addresses.

It would be nice if some of the blocking sites I've contacted would reply back with their reasons, but I'm not holding my breath.

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http://www.ingber.com