IP blocking issue
Posted: 24 Feb 2021, 10:15
Hi there,
Recently we've started getting refused connections to other hosts from multiple servers, nothing is set to block these on the outbound server and a traceroute will follow the whole route bar the destination machine itself. As soon as CSF is turned off, connection can be established and traceroute completes; which would imply the server is blocking something this end thats necessary for a handshake. Destination hosts confirm that nothing is being blocked their end. Do you have any idea what could be causing this?
You can not ping the said IP's from the server either until CSF is disabled. All ports are set as default, no IP's in the block list.
This is not an isolated case, and is happening across multiple cPanel servers. Mail sending to addresses on other servers is then failing, which is how we picked this up.
Please note that this is not for all servers, only some.
Recently we've started getting refused connections to other hosts from multiple servers, nothing is set to block these on the outbound server and a traceroute will follow the whole route bar the destination machine itself. As soon as CSF is turned off, connection can be established and traceroute completes; which would imply the server is blocking something this end thats necessary for a handshake. Destination hosts confirm that nothing is being blocked their end. Do you have any idea what could be causing this?
You can not ping the said IP's from the server either until CSF is disabled. All ports are set as default, no IP's in the block list.
This is not an isolated case, and is happening across multiple cPanel servers. Mail sending to addresses on other servers is then failing, which is how we picked this up.
Please note that this is not for all servers, only some.