Skip to content
cathrynmataga's profile

New Member


1 Message

Saturday, June 29th, 2019 4:00 PM

I'm seeing ipip traffic getting dropped by a comcast router,

My IPIP, portocol 4 packets are going out fine. But ipip packets coming back into comcast are getting blocked at  This has been happening for a few months or so, it used to work. But it broke, and it's taken until now to figure out what's really going on.   IPIP is used like a VPN, to connect to another network using different IP addresses.  This is the message I got from the guys I work with on the other end of the connection.

Thank you!


This suggests that something is filtering out protocol 4 (IPIP)
between and

A traceroute from to using ordinary
UDP works, completing after 18 hops.  The last few hops in that
path look like this:

14  12.097 ms  12.315 ms  12.088 ms
15  12.735 ms  12.744 ms  12.773 ms
16  13.080 ms  12.983 ms  12.920 ms
17  * * *
18  37.676 ms  42.664 ms  33.084 ms

A traceroute from to using protocol 4
(IPIP) does not complete, and there are no responses beyond hop
15.  The last few hops are:

12  11.117 ms  12.601 ms  12.734 ms
13  11.761 ms  11.743 ms  11.340 ms
14  12.469 ms  12.162 ms  12.392 ms
15  12.757 ms  12.800 ms  12.797 ms
16  * * *
17  * * *
18  * * *

This suggests that hop 16,, is not accepting/passing
protocol 4 packets.  The hostname for that host is


Official Employee


526 Messages

5 years ago

Thank you for taking the time to reach out us through our business forums. I am happy to assist with the connectivity issues. Can you please reach out through private message with your first and last name, the service address and the account number or phone number?