On Sat, 4 Sep 2004, Lew Bloch wrote: > >> How about moving sshd from 22 to another port (85?) that only you and he > >> would know. Then he would ssh to -p 85. Anyone ssh to -p 22 would get a > >> timeout. > > > > Thought about that...but if anyone is port scanning my network they would > > evently find the open port and it's a matter to time. > > OK, then they know you exist, but that doesn't necessarily mean they can > compromise your system. I haven't figured out how to be generally > invisible except to friendlies, but one can allow ingress to members of > only specific groups via the /etc/ssh/sshd_config "AllowGroups" entry > (or to specific users via "AllowUsers"). > > For example, you can create a group "frobozz" and put your friend's id > in that group, then put a line in /etc/ssh/sshd_config > "AllowGroups" frobozz > > Of course, you'll also want to have a line > PermitRootLogin no > > I, too, am curious how to make the port visible to only the select few, > but I don't think it can be done. The best I've found is to deny entry > to those undesirables who do find my (non-standard) SSH port. Is there > such a magic bullet? I think that y'all are looking for something called "port knocking": http://netsecurity.about.com/cs/generalsecurity/a/aa032004.htm Basic idea...a daemon listens to all connection attempts to all ports. When it detects a specific pattern, it will open the port that you define. It won't help if somebody's actually sniffing one of the end-points, because the bad guy will be able to record the knock sequence. Other than that, it's not a bad idea. I haven't used it, but there's a linux program that claims to do this: http://www.zeroflux.org/knock/ Good luck. Ben -- redhat-list mailing list unsubscribe mailto:redhat-list-request@xxxxxxxxxx?subject=unsubscribe https://www.redhat.com/mailman/listinfo/redhat-list