top-like netfilter TCP / UDP / SCTP / DCCP / ICMP (v6) отслеживание потока (top-like netfilter TCP/UDP/SCTP/DCCP/ICMP(v6) flow tracking)
Имя (Name)
flowtop - top-like netfilter TCP/UDP/SCTP/DCCP/ICMP(v6) flow
tracking
Синопсис (Synopsis)
flowtop { [options] }
Описание (Description)
flowtop is a top-like connection tracking tool that can run on an
end host or small home router. It is able to present TCP,
UDP/UDP-lite, SCTP, DCCP, and ICMP(v6) flows that have been
collected by the kernel's netfilter connection tracking
framework, thus no packet capturing in user space needs to be
done.
flowtop is able to give you a quick overview of current
connections on your local system, e.g. for debugging purposes or
to answer questions like:
* If you access website X, what other connections are being
opened in
the background that I'm not aware of?
* What connections are active that pass one's router?
* I have this proprietary binary Y, to where does it connect?
* To which countries am I sending data?
* Are there any suspicious background connections on my
machine?
* How many active connections does binary Y have?
* How long are connections active already?
* At which rate am I sending/receiving data?
The following information will be presented in flowtop's output:
* Application name and PID when run on local machine
* Reverse DNS for source and destination
* Geo-location information (country, city)
* Used protocols (IPv4, IPv6, TCP, UDP, SCTP, ICMP, ...)
* Flow port's service name heuristic
* Transport protocol state machine information
* Byte/packet counters (if they are enabled)
* Connection duration (if timestamping is enabled)
* Flow send/receive rate (if byte/packet counters are
enabled)
In order for flowtop to work, netfilter must be active and
running on your machine, thus kernel-side connection tracking is
active. If netfilter is not running, you can activate it with
iptables(8):
iptables -A INPUT -p tcp -m state --state ESTABLISHED -j
ACCEPT
iptables -A OUTPUT -p tcp -m state --state NEW,ESTABLISHED -j
ACCEPT
or by loading the following kernel modules:
modprobe nf_conntrack_ipv4
modprobe nf_conntrack_ipv6
To dump byte/packet counters flowtop enables the sysctl(8)
parameter net.netfilter.nf_conntrack_acct via:
echo 1 > /proc/sys/net/netfilter/nf_conntrack_acct
and resets it to the previously set value on exit. These counters
will only be active on connections which were created after
accounting was enabled. Thus, to have these counters be active
all the time the parameter should be enabled after the system is
up. To automatically enable it, sysctl.conf(8) or sysctl.d(8)
might be used.
To calculate the connection duration flowtop enables the
sysctl(8) parameter net.netfilter.nf_conntrack_timestamp via:
echo 1 > /proc/sys/net/netfilter/nf_conntrack_timestamp
and resets it to the previously set value on exit.
flowtop's intention is just to get a quick look over your active
connections. If you want logging support, have a look at
netfilter's conntrack(8) tools instead.
Параметры (Options)
-4, --ipv4
Display IPv4 flows. That is the default when flowtop is
started without any arguments.
-6, --ipv6
Display IPv6 flows. That is the default when flowtop is
started without any arguments.
-T, --tcp
Display TCP flows. That is the default when flowtop is
started without any arguments.
-U, --udp
Display UDP and UDP-lite flows.
-D, --dccp
Display DCCP flows.
-I, --icmp
Display ICMP version 4 and version 6 flows.
-S, --sctp
Display SCTP flows.
-n, --no-dns
Don't perform hostname lookup. Only numeric addresses will
be shown for flow endpoints.
-G, --no-geoip
Don't perform GeoIP lookup. No geographical information
will be shown for flow endpoints.
-s, --show-src
Also show source information of the flow, not only
destination information.
-b, --bits
Show flow rates in bits per second instead of bytes per
second.
-u, --update
The built-in database update mechanism will be invoked to
get Maxmind's latest database. To configure search
locations for databases, the file /etc/netsniff-
ng/geoip.conf contains possible addresses. Thus, to save
bandwidth or for mirroring Maxmind's databases (to bypass
their traffic limit policy), different hosts or IP
addresses can be placed into geoip.conf, separated by a
newline.
-t <time>, --interval <time>
Flow info refresh interval in seconds, default is 1s.
-v, --version
Show version information and exit.
-h, --help
Show user help and exit.
Примеры использования (Usage example)
flowtop
Default ncurses output for flowtop that tracks IPv4, IPv6
flows for TCP.
flowtop -46UTDISs
This example enables the maximum display options for
flowtop.
Конфигурационный файл (Config file)
Files under /etc/netsniff-ng/ can be modified to extend flowtop's
service resolution and lookup information.
* tcp.conf - TCP port/services map
* udp.conf - UDP port/services map
* geoip.conf - GeoIP database mirrors
Ошибки (баги) (Bugs)
With a fairly high rate of connection tracking updates, flowtop
can become unresponsive for short periods of time while
scrolling. The right fix would be to replace flowtop's connection
management backend with a better design with respect to the
locking approach. This is still on the "todo" list.
История (History)
flowtop was originally written for the netsniff-ng toolkit by
Daniel Borkmann. It is currently maintained by Tobias Klauser
<tklauser@distanz.ch> and Daniel Borkmann
<dborkma@tik.ee.ethz.ch>.
Смотри также (See also)
netsniff-ng(8), trafgen(8), mausezahn(8), ifpps(8), bpfc(8),
astraceroute(8), curvetun(8), iptables(8), sysctl(8),
sysctl.conf(8), sysctl.d(8)
