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Why can I only access protected resources over VPN on some networks?

Location          | SSH to GitHub | SSH to private IP 
------------------|---------------|-------------------
On-campus Wi-Fi   | Yes           | Yes
Coffee shop A     | Yes           | Only on VPN
Coffee shop B     | Only on VPN   | No

Here is the output when I try to SSH while connected to the University VPN (Cisco/IPSec) at coffee shop B:

$ ssh -T git@github.com
Hi RinkAttendant6! You've successfully authenticated, but GitHub does not provide shell access.

$ ssh 10.X.X.X
ssh: connect to host 10.X.X.X port 22: No route to host

Is the coffee shop able to inspect the VPN traffic to determine whether I'm connecting to GitHub or an internal network, or is there another explanation for these results?

Everything works as expected at coffee shop A, if I understand this answer correctly: https://networkengineering.stackexchange.com/a/23976

  • 3
    The coffee shop b may be assigning you a local IP address in the 10.X.X.X range, (which is in the range of the host your attempting to SSH to through the VPN) and that may be your conflict. – Daisetsu Oct 8 '18 at 3:34
  • @Daisetsu I think this is the case. Feel free to add an answer (and if you know how to resolve the issue on Linux and/or Windows that would be even better :D) – rink.attendant.6 Oct 8 '18 at 23:06
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From my comment: The coffee shop B may be assigning you a local IP address in the 10.X.X.X range, (which is in the range of the host your attempting to SSH to through the VPN) and that may be your conflict.

Resolution: After a bit of searching I found a similar question and answer over on server fault. The easy solution is to change your internal IPs to a range that's not allocated by most coffee shops, hotels, etc 10.123.0.* maybe. The complicated solution that's more reliable is not tricks as mentioned in the accepted and we're.

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