06-21-2011 07:57 AM - edited 03-11-2019 01:48 PM
I have the specified configurations on my 2821 router
interface FastEthernet0/0
ip address 66.x.x.x 255.255.255.248
ip access-group INBOUND in
no ip redirects
ip nbar protocol-discovery
ip inspect fw out
speed 100
full-duplex
service-policy input FTP-QoS
service-policy output FTP-QoS
Following is the fw desctiption applied on outbound direction.
ip inspect name fw dns
ip inspect name fw tcp
ip inspect name fw udp
ip inspect name fw icmp
ip inspect name fw ftp
ip inspect name fw http
ip inspect name fw https
ip inspect name fw pop3
ip inspect name fw imap3
ip inspect name fw ntp
ip inspect name fw ftps
ip inspect name fw isakmp
ip inspect name fw ipsec-msft
ip inspect name fw l2tp
Inbound ACL Description.
Extended IP access list INBOUND
100 permit tcp any host 66.x.x.x eq 22 log (51 matches)
110 permit tcp any 209.x.x.0 0.0.0.255 eq 10111 log (9089431 matches)
120 permit tcp any 209.x.x.0 0.0.0.255 eq 10112 log
130 permit tcp any 209.x.x.0 0.0.0.255 eq 10113 log (11781 matches)
140 permit tcp any 209.x.x.0 0.0.0.255 eq 10311 log (800041 matches)
150 permit tcp any 209.x.x.0 0.0.0.255 eq 10313 log (1423114 matches)
160 permit tcp any 209.x.x.0 0.0.0.255 eq 10315 log
170 permit tcp any 209.x.x.0 0.0.0.255 eq 10316 log
180 permit tcp any 209.x.x.0 0.0.0.255 eq 10321 log (417 matches)
1700 permit tcp any any established log (175963 matches)
1710 permit icmp any any echo-reply log (1 match)
1720 deny ip any any log (211516 matches)
I have recently attacked by a DOS attack in which source port was 80 , is there any issues with my configs . As according to the above configs port 80 isnt allowed in .
Can any one please confirm.
Thanks
06-23-2011 03:45 PM
Your FW is inspecting all outgoing http traffic so that return packets are allowed through the acl applied inbound on the interface. The return packets will have the source port of 80 so its possible that if there is man-in-the middle attacks somebody hijacks the initial connection going on destination port 80 and responds with source port of 80.
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