alert tcp any !$SSH_PORTS -> any any (msg:"ET POLICY SSHv2 Server KEX Detected within Banner on Unusual Port"; flow:from_server,established; flowbits:noalert; content:"SSH-"; offset:0; depth:4; byte_test:1,>,48,0,relative; byte_test:1,<,51,0,relative; byte_test:1,=,46,1,relative; content:"|0d 0a|"; offset:4; depth:255; byte_test:1,=,20,5,relative; flowbits:set,ET.is_ssh_server_banner; flowbits:set,ET.is_ssh_server_kex; reference:url,www.proftpd.org/docs/contrib/mod_sftp.html; classtype:misc-activity; sid:2022326; rev:2; metadata:created_at 2016_01_01, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)