TCP or UDP ports operate at L4 but firewalls (ASA or PIX) are able to inspect packets to application level...
Its used when common ports (TCP 80 for web brosing or TCP 21 for FTP) are used by P2P applications like Kazaa, eMule. Skype...
administrators permit traffic from network for port 80 (because it is used for web browsing) - but TCP 80 can be also misused by P2P applications
With access list you cannot see what traffic flows on port 80.. ACL only looks on destination port - its TCP 80 - OK its permitted and access is allowed BUT with application inspection firewall is able look deeper inside packet and see there is no HTTP commands inside packet ( CONNECT Command, DISCONNECT Command, GET Command, HEAD Command etc..) so firewall is able to recognize non-HTTP traffic (non-FTP) on port 80 (21) a deny such malicious traffic
Question We run asr9001 with XR 6.1.3, and we have a very long delay to
login w/ SSH 1 or 2 to the device compare to IOS device. After
investigation, the there is 1s delay between the client KEXDH_INIT and
the server (XR) KEXDH_REPLY. After debug ssh serv...
Introduction The purpose of this document is to demonstrate the Open
Shortest Path First (OSPF) behavior when the V-bit (Virtual-link bit) is
present in a non-backbone area. The V-bit is signaled in Type-1 LSA only
if the router is the endpoint of one or ...
Hi, I am seeing quite a few issues with patch install and wanted to
share my experience and workaround to this. Login to admin via CLI, then
access root with the “shell” command Issue “df –h” and you’ll probably
see the following directory full or nearly ...