Fine tuning portscan

["Lay, James" <james.lay () wincofoods com>]

Hey all!

So...here's what I got...I usually see a fair amount of the below in the
firewall logs:

Oct 25 08:57:31 10.10.253.249 Deny tcp 61.147.103.174 ext_ip_1 7000 21
offset 5 S 963131176 win 64
Oct 25 08:57:31 10.10.253.249 Deny tcp 61.147.103.174 ext_ip_2 7000 21
offset 5 S 963131176 win 64 
Oct 25 08:57:31 10.10.253.249 Deny tcp 61.147.103.174 ext_ip_3 7000 21
offset 5 S 963131176 win 64

The IDS instance is listening in front of the firewall.  Here's from my
snort.conf:

preprocessor stream5_global: track_tcp yes, track_udp yes, track_icmp
no, max_tcp 262144, max_udp 131072, max_active_responses 2,
min_response_seconds 5
preprocessor stream5_tcp: policy windows, require_3whs 180, \
   overlap_limit 10, small_segments 3 bytes 150, timeout 180, \
    ports client 21 22 23 25 42 53 79 109 110 111 113 119 135 136 137
139 143 161 445 513 514 587 593 691 1433 1521 2100 3306 6070 6665 6666
6667 6668 6669 7000 8181 32770 32771 32772 32773 32774 32775 32776 32777
32778 32779,
    ports both 80 81 311 443 465 563 591 593 636 901 989 992 993 994 995
1220 1414 1830 2301 2381 2809 3128 3702 4343 5250 7907 7001 7145 7510
7802 7777 7779 7801 7900 7901 7902 7903 7904 7905 7906 7908 7909 7910
7911 7912 7913 7914 7915 7916 7917 7918 7919 7920 8000 8008 8014 8028
8080 8088 8118 8123 8180 8243 8280 8800 8888 8899 9080 9090 9091 9443
9999 11371 55555

preprocessor sfportscan: proto  { all } memcap { 10000000 } scan_type {
all } watch_IP { ext_netblock } ignore_scanners { ext_netblock }
sense_level { high } logfile { /opt/var/log/twext/portscan.log }

I am seeing:

Time: 10/25-08:12:20.738256
event_ref: 0
129.42.58.216 -> ext_ip (portscan) TCP Distributed Portscan
Priority Count: 10
Connection Count: 6
IP Count: 83
Scanner IP Range: 1.52.120.165:216.153.41.227
Port/Proto Count: 10
Port/Proto Range: 25:58000

However it seems to require q pretty beefy amount of connection counts.
My goal is to match on very small one ip -> many ip's, same port.

Am I missing something somewhere?  Should I insert say port 21 into
"ports both"?  Danke :)

James

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