I have a firewall where I was blocking Internet access only to Windows
clients. I have the osf module, the last version of the fingerprint file
from the openbsd web, and this rule:
iptables -I FORWARD -j DROP -p tcp -m osf --genre Windows --smart
This worked for some time but yesterday I checked it and now you can surf
the web from Windows and Linux. I have tried to add a rule to drop all
connections and insert a new one before that which accepts connections only
from Linux, but it doesn't work either. It's like it is unable to identify
the operating system, it doesn't seem to be about dropping connections
because I can drop every connection by inserting a drop rule without the
"-m osf --genre Windows --smart"
If I go to
http://lcamtuf.coredump.cx/p0f-help/
it identifies my OS correctly, both if I visit it from Windows and Linux.
How can do the same test for the osf module that is installed in my
firewall?
This is the output of iptables -L:
Chain ACCEPT_ALL (1 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere state NEW
ACCEPT all -- anywhere anywhere
ACCEPT icmp -- anywhere anywhere icmp
echo-request
Chain BADTCP (2 references)
target prot opt source destination
PSCAN tcp -- anywhere anywhere tcp
flags:FIN,SYN,RST,PSH,ACK,URG/FIN,PSH,URG
PSCAN tcp -- anywhere anywhere tcp
flags:FIN,SYN,RST,PSH,ACK,URG/NONE
PSCAN tcp -- anywhere anywhere tcp
flags:FIN,SYN,RST,PSH,ACK,URG/FIN
PSCAN tcp -- anywhere anywhere tcp
flags:SYN,RST/SYN,RST
PSCAN tcp -- anywhere anywhere tcp
flags:FIN,SYN/FIN,SYN
NEWNOTSYN tcp -- anywhere anywhere tcp
flags:!FIN,SYN,RST,ACK/SYN state NEW
Chain BLUEINPUT (1 references)
target prot opt source destination
Chain CUSTOMFORWARD (1 references)
target prot opt source destination
Chain CUSTOMINPUT (1 references)
target prot opt source destination
Chain CUSTOMOUTPUT (1 references)
target prot opt source destination
Chain DHCPBLUEINPUT (1 references)
target prot opt source destination
Chain DMZHOLES (1 references)
target prot opt source destination
Chain INPUT (policy DROP)
target prot opt source destination
ipac~o all -- anywhere anywhere
BADTCP all -- anywhere anywhere
tcp -- anywhere anywhere tcp
flags:SYN,RST,ACK/SYN limit: avg 10/sec burst 5
CUSTOMINPUT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere state
RELATED,ESTABLISHED
ACCEPT icmp -- anywhere anywhere icmp
echo-request
ACCEPT all -- anywhere anywhere state NEW
DROP all -- 127.0.0.0/8 anywhere state NEW
DROP all -- anywhere 127.0.0.0/8 state NEW
ACCEPT !icmp -- anywhere anywhere state NEW
ACCEPT all -- anywhere anywhere
BLUEINPUT !icmp -- anywhere anywhere state NEW
ORANGEINPUT !icmp -- anywhere anywhere state NEW
OUTGOINGFW all -- anywhere anywhere state NEW
DHCPBLUEINPUT all -- anywhere anywhere
OPENVPN all -- anywhere anywhere state NEW
IPSECRED all -- anywhere anywhere
IPSECBLUE all -- anywhere anywhere
REDINPUT all -- anywhere anywhere
XTACCESS all -- anywhere anywhere state NEW
LOG all -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `INPUT '
Chain FORWARD (policy DROP)
target prot opt source destination
DROP tcp -- anywhere anywhere OS fingerprint
match Windows
ipac~fi all -- anywhere anywhere
ipac~fo all -- anywhere anywhere
BADTCP all -- anywhere anywhere
TCPMSS tcp -- anywhere anywhere tcp
flags:SYN,RST/SYN TCPMSS clamp to PMTU
CUSTOMFORWARD all -- anywhere anywhere
ACCEPT all -- anywhere anywhere state
RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere state NEW
DROP all -- 127.0.0.0/8 anywhere state NEW
DROP all -- anywhere 127.0.0.0/8 state NEW
ACCEPT_ALL all -- anywhere anywhere
OUTGOINGFW all -- anywhere anywhere state NEW
OPENVPN all -- anywhere anywhere state NEW
DMZHOLES all -- anywhere anywhere state NEW
PORTFWACCESS all -- anywhere anywhere state NEW
LOG all -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `FORWARD '
Chain IPSECBLUE (1 references)
target prot opt source destination
Chain IPSECRED (1 references)
target prot opt source destination
Chain LOG_DROP (0 references)
target prot opt source destination
LOG all -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning
DROP all -- anywhere anywhere
Chain LOG_REJECT (0 references)
target prot opt source destination
LOG all -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning
REJECT all -- anywhere anywhere reject-with
icmp-port-unreachable
Chain NEWNOTSYN (1 references)
target prot opt source destination
LOG all -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `NEW not SYN? '
DROP all -- anywhere anywhere
Chain OPENVPN (2 references)
target prot opt source destination
Chain ORANGEINPUT (1 references)
target prot opt source destination
Chain OUTGOINGFW (2 references)
target prot opt source destination
ACCEPT tcp -- anywhere anywhere tcp dpt:http
ACCEPT tcp -- anywhere anywhere tcp dpt:https
ACCEPT tcp -- anywhere anywhere tcp dpt:ftp
ACCEPT tcp -- anywhere anywhere tcp
dpt:ftp-data
ACCEPT tcp -- anywhere anywhere tcp dpt:smtp
ACCEPT tcp -- anywhere anywhere tcp dpt:pop3
ACCEPT tcp -- anywhere anywhere tcp dpt:imap
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:ntp
ACCEPT udp -- anywhere anywhere udp dpt:ntp
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ipac~i all -- anywhere anywhere
CUSTOMOUTPUT all -- anywhere anywhere
Chain PORTFWACCESS (1 references)
target prot opt source destination
ACCEPT tcp -- anywhere 192.168.0.71 tcp dpt:http
ACCEPT tcp -- anywhere 192.168.0.70 tcp dpt:smtp
ACCEPT tcp -- anywhere 192.168.0.70 tcp dpt:imap
Chain PSCAN (5 references)
target prot opt source destination
LOG tcp -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `TCP Scan? '
LOG udp -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `UDP Scan? '
LOG icmp -- anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `ICMP Scan? '
LOG all -f anywhere anywhere limit: avg
10/min burst 5 LOG level warning prefix `FRAG Scan? '
DROP all -- anywhere anywhere
Chain REDINPUT (1 references)
target prot opt source destination
Chain SIPROXD (0 references)
target prot opt source destination
Chain XTACCESS (1 references)
target prot opt source destination
ACCEPT tcp -- anywhere 192.168.1.175 tcp dpt:ident
Chain ipac~fi (1 references)
target prot opt source destination
all -- anywhere anywhere
all -- anywhere anywhere
Chain ipac~fo (1 references)
target prot opt source destination
all -- anywhere anywhere
all -- anywhere anywhere
Chain ipac~i (1 references)
target prot opt source destination
all -- anywhere anywhere
all -- anywhere anywhere
Chain ipac~o (1 references)
target prot opt source destination
all -- anywhere anywhere
all -- anywhere anywhere
