On 2020-02-01 04:56, Samuel Sieb wrote: > On 1/31/20 12:35 PM, Ed Greshko wrote: >> On 2020-02-01 04:31, Samuel Sieb wrote: >>> Your original post was completely clear. However, something is happening >>> on your network that you aren't aware of. The fact that you are getting >>> connections from an external IP address means that somehow there is a path >>> from the external internet to this computer. It's possible that another >>> computer on your network could somehow be routing incoming packets to the >>> computer, but the outgoing ones have to be following the default route to >>> the default gateway. An interesting split routing. tcpdump (or wireshark) >>> will give you the mac address and if it doesn't match your gateway, you >>> will have to track down which computer has that mac. >> >> And in that regard the "arp" command may be useful. That is if one is aware >> of what IP addresses on >> the LAN belong to what devices. > > I thought about that, but it's only useful for mapping back from the MAC > address and that would only work if the computers are talking directly using > local addresses. Only the attacking computer would have an arp entry for the > target computer. If the target does not normally have any communication with > the attacker, it won't have an entry for it. If he has access to the gateway > computer, then that would more likely have an arp entry for the attacker.
Well since arp is only on the LAN and since LAN communication is arp based the tcpdump packets will have the MAC address of the device on the local network from which the ssh packets were routed through. Normally, that would be the MAC of the gateway/firewall (assuming they are the same). But at least one would know the previous hop. > > One more thing I just thought of, depending on the network structure, the > incoming packets could also be coming through the default gateway which would > be even more difficult to track down. But without the MAC address, it's all > just speculation. And if the incoming packets have the MAC address of the default gw and the default gw is also the firewall then that would indicate the firewall is not doing what the OP thinks it is doing. -- The key to getting good answers is to ask good questions. _______________________________________________ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
