[SSHd] Increasing wait time?

[Doug Hardie]

On May 6, 2008, at 10:57, Randy Ramsdell wrote:

> David Kelly wrote:
>> On Tue, May 06, 2008 at 09:31:15AM -0800, Beech Rintoul wrote:
>>
>>>> Is there a way to configure SSHd, so that the wait time between
>>>> login attempts increases after X failed tries?
>>>>
>>> Not that I know of. You should look into denyhosts (in the ports) it
>>> works well and even has a RBL feature to block some of these script
>>> kiddies proactively. Unfortunately, these attempts have become a  
>>> fact
>>> of life. I probably get 20 - 30 attempts a day between my various
>>> servers.
>>>
>>
>> Depending on how you use ssh from external systems you could add
>> firewall rules to disallow all but known sources.
>>
>>
> I used portsentry several years ago which is a realtime portscan  
> blocker. It would trigger on this type of ssh portscan for sure. One  
> problem is that it blocks using  firewall rules, hosts.deny etc...  
> and would have to be actively maintained. Meaning: I cleaned these  
> entries once a week. I am not sure it is ported to BSD either.

Another option is to change the port SSH uses to some very unusual  
port.  I do this on all the systems I use and change the port settings  
in ssh.conf and sshd.conf.  This approach works if you don't have lots  
of users using SSH as it does require some sophistication to work with  
it.  Since I have only 3 people who can use SSH it works great for me.