Hi,
Though I have some Linux background I'm new to BSD. Currently I'm administering an OpenBSD 5.3 firewall which based on PF.
I want to view my top talkers to the internet. If it is a graphical one that's better but I like to know whether it is possible through a command like pfctl a help... (1 Reply)
My Office Hours between 10 A.M to 5 P.M .I am managing 16 client PCs which is remotely placed. I want to know the network status of every client PCs.I need an automatic trigger mail ,when the network connection is lost in any one of the Client PCs during office hours.I am a self study learner.I... (9 Replies)
Hi all,
I got following configuration problem
I need to configure tiny network on openbsd
I got server1 with 3 interfaces vic0 em0 em1
The interface vic0 on server1 has follwoing IP 172.16.1.1
em0
firstly I would like to configure network under em0 (I have assigned to em0 following... (1 Reply)
I Colleagues,
Somebody can say me how to monitoring traffic in the network. also I am interested in monitoring memory. if somebody to know a guide with command advanced in unix welcome for me.
Thank you for adcanced. (0 Replies)
hi
can i know if there is any GUI interface software to help in monitoring the network of the servers i have? something like a web pages or a stock pages when a processes is down, a red colour is flashes. best if it is free ;) (1 Reply)
This feels really silly, but i just dont get it..
I just installed openbsd on one of my machines, usually
i dont have this problem, but now, when i try to use ifconfig
to give myself an ipadress, i get this errormsg:
OpenAMD# ifconfig ep0 192.168.51.16
ifconfig: SIOCGIFFLAGS: Device not... (5 Replies)
PF.OS(5) BSD File Formats Manual PF.OS(5)NAME
pf.os -- format of the operating system fingerprints file
DESCRIPTION
The packet filter firewall and the tcpdump(1) program can both fingerprint the operating system of hosts that originate an IPv4 TCP connec-
tion. The file consists of newline-separated records, one per fingerprint, containing nine colon (':') separated fields. These fields are
as follows:
window The TCP window size.
TTL The IP time to live.
df The presence of the IPv4 don't fragment bit.
packet size The size of the initial TCP packet.
TCP options An ordered list of the TCP options.
class The class of operating system.
version The version of the operating system.
subtype The subtype of patchlevel of the operating system.
description The overall textual description of the operating system, version and subtype.
The window field corresponds to the th->th_win field in the TCP header and is the source host's advertised TCP window size. It may be
between zero and 65,535 inclusive. The window size may be given as a multiple of a constant by prepending the size with a percent sign '%'
and the value will be used as a modulus. Three special values may be used for the window size:
* An asterisk will wildcard the value so any window size will match.
S Allow any window size which is a multiple of the maximum segment size (MSS).
T Allow any window size which is a multiple of the maximum transmission unit (MTU).
The ttl value is the initial time to live in the IP header. The fingerprint code will account for the volatility of the packet's TTL as it
traverses a network.
The df bit corresponds to the Don't Fragment bit in an IPv4 header. It tells intermediate routers not to fragment the packet and is used for
path MTU discovery. It may be either a zero or a one.
The packet size is the literal size of the full IP packet and is a function of all of the IP and TCP options.
The TCP options field is an ordered list of the individual TCP options that appear in the SYN packet. Each option is described by a single
character separated by a comma and certain ones may include a value. The options are:
Mnnn maximum segment size (MSS) option. The value is the maximum packet size of the network link which may include the '%'
modulus or match all MSSes with the '*' value.
N the NOP option (NO Operation).
T[0] the timestamp option. Certain operating systems always start with a zero timestamp in which case a zero value is added to
the option; otherwise no value is appended.
S the Selective ACKnowledgement OK (SACKOK) option.
Wnnn window scaling option. The value is the size of the window scaling which may include the '%' modulus or match all window
scalings with the '*' value.
No TCP options in the fingerprint may be given with a single dot '.'.
An example of OpenBSD's TCP options are:
M*,N,N,S,N,W0,N,N,T
The first option M* is the MSS option and will match all values. The second and third options N will match two NOPs. The fourth option S
will match the SACKOK option. The fifth N will match another NOP. The sixth W0 will match a window scaling option with a zero scaling size.
The seventh and eighth N options will match two NOPs. And the ninth and final option T will match the timestamp option with any time value.
The TCP options in a fingerprint will only match packets with the exact same TCP options in the same order.
The class field is the class, genre or vendor of the operating system.
The version is the version of the operating system. It is used to distinguish between different fingerprints of operating systems of the
same class but different versions.
The subtype is the subtype or patch level of the operating system version. It is used to distinguish between different fingerprints of oper-
ating systems of the same class and same version but slightly different patches or tweaking.
The description is a general description of the operating system, its version, patchlevel and any further useful details.
EXAMPLES
The fingerprint of a plain OpenBSD 3.3 host is:
16384:64:1:64:M*,N,N,S,N,W0,N,N,T:OpenBSD:3.3::OpenBSD 3.3
The fingerprint of an OpenBSD 3.3 host behind a PF scrubbing firewall with a no-df rule would be:
16384:64:0:64:M*,N,N,S,N,W0,N,N,T:OpenBSD:3.3:!df:OpenBSD 3.3 scrub no-df
An absolutely braindead embedded operating system fingerprint could be:
65535:255:0:40:.:DUMMY:1.1:p3:Dummy embedded OS v1.1p3
The tcpdump(1) output of
# tcpdump -s128 -c1 -nv 'tcp[13] == 2'
03:13:48.118526 10.0.0.1.3377 > 10.0.0.2.80: S [tcp sum ok]
534596083:534596083(0) win 57344 <mss 1460> (DF) [tos 0x10]
(ttl 64, id 11315, len 44)
almost translates into the following fingerprint
57344:64:1:44:M1460: exampleOS:1.0::exampleOS 1.0
SEE ALSO pf.conf(5), pfctl(8), tcpdump(1)BSD May 31, 2007 BSD