I am just wondering if a DOS attack saturates a link, does a routing protocol keepalive/Hello packet still have the highest priority to be sent out the link by default or do I have to set up some kind of QOS to prevent this from happening? I remember from somewhere that traffic generates from the router has the highest priority by default. Can someone show me a documentation? Thank you!
yes indeed QOS is one of the solutions that mitigate DOS or distributed DOS attacks if used correctly i.e all control protocols including hellos.. have an ip precedence of 6 or 7 so if you assign other traffics those ip precende you may run into some issues since the control protocols will have the same priority in treatement as that traffic with 6 or 7.
also if you configure qos this control protocols will have 25 percent of the available bandwidth by default UNLESS YOU TOuch the command max-reserved-bandwidth.
but qos only is not sufficient ie if a hacker send tousands or handreds of thousand of fragmented packet that will eat up all your CPU so you end up with crashed router, same if some send a lot of half open tcp session , or half open udp that will eat up your memory..
so qos with other tools can help mitigate that kind of attacks but still DOS attack remains one the most difficult to eliminate totaly. other tools are specialized devices IPS IDS PIX ASA...
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.