mirror of
https://github.com/yarrick/iodine.git
synced 2024-11-08 02:19:18 +02:00
#76 start merging common and docs
This commit is contained in:
parent
ed36bbdf65
commit
eb0bf45396
130
README
130
README
|
@ -94,6 +94,41 @@ should always work. For more bandwidth, try Base64 or Raw (TXT only) via the
|
|||
-O option. If Base64/Raw doesn't work, you'll see many failures in the
|
||||
fragment size autoprobe.
|
||||
|
||||
Normal operation now is for the server to _not_ answer a DNS request until
|
||||
the next DNS request has come in, a.k.a. being "lazy". This way, the server
|
||||
will always have a DNS request handy when new downstream data has to be sent.
|
||||
This greatly improves (interactive) performance and latency, and allows to
|
||||
slow down the quiescent ping requests to 4 second intervals by default.
|
||||
In fact, the main purpose of the pings now is to force a reply to the previous
|
||||
ping, and prevent DNS server timeouts (usually 5-10 seconds per RFC1035).
|
||||
In the unlikely case that you do experience DNS server timeouts (SERVFAIL),
|
||||
decrease the -I option to 1. If you are running on a local network without
|
||||
any DNS server in-between, try -I 50 (iodine and iodined time out after 60
|
||||
seconds). The only time you'll notice a slowdown, is when DNS reply packets
|
||||
go missing; the iodined server then has to wait for a new ping to re-send the
|
||||
data. You can speed this up by generating some upstream traffic (keypress,
|
||||
ping). If this happens often, check your network for bottlenecks and/or run
|
||||
with -I1 .
|
||||
|
||||
Some DNS servers appear to be quite impatient and start retrying DNS requests
|
||||
(with _different_ DNS ids!) when an answer does not appear within a few
|
||||
milliseconds. Usually they scale back retries when iodined's lazy mode
|
||||
repeatedly takes several seconds to answer; and they scale up retries again
|
||||
when iodined answers fast during heavy data transfer. Some commercial DNS
|
||||
servers advertise this as "carrier-grade adaptive retransmission techniques".
|
||||
The effect will only be visible in the network traffic at the iodined server,
|
||||
and will not affect the client's connection. Iodined has rather elaborate
|
||||
logic to deal with (i.e., ignore) these unwanted duplicates.
|
||||
|
||||
Other DNS servers, notably the opendns.com network, seem to regard iodined's
|
||||
lazyness as incompetency, and will start shuffling requests around, possibly
|
||||
in an attempt to reduce iodined's workload. The resulting out-of-sequence DNS
|
||||
traffic works quite badly for lazy mode. The iodine client will detect this,
|
||||
and switch back to legacy mode ("immediate ping-pong") automatically. In these
|
||||
cases, start the iodine client with -L0 to prevent it from operating in lazy
|
||||
mode altogether. Note that this will negatively affect interactive performance
|
||||
and latency, especially in the downstream direction.
|
||||
|
||||
If you have problems, try inspecting the traffic with network monitoring tools
|
||||
and make sure that the relaying DNS server has not cached the response. A
|
||||
cached error message could mean that you started the client before the server.
|
||||
|
@ -109,12 +144,103 @@ iptables -t nat -A PREROUTING -i eth0 -p udp --dport 53 -j DNAT --to :5353
|
|||
(Sent in by Tom Schouten)
|
||||
|
||||
Iodined will reject data from clients that have not been active (data/pings)
|
||||
for more than 60 seconds. In case of a long network outage or similar, just
|
||||
stop iodine and restart (re-login), possibly multiple times until you get
|
||||
for more than 60 seconds. Similarly, iodine will exit when no downstream
|
||||
data has been received for 60 seconds. In case of a long network outage or
|
||||
similar, just restart iodine (re-login), possibly multiple times until you get
|
||||
your old IP address back. Once that's done, just wait a while, and you'll
|
||||
eventually see the tunneled TCP traffic continue to flow from where it left
|
||||
off before the outage.
|
||||
|
||||
With the introduction of the downstream packet queue in the server, its memory
|
||||
usage has increased with several megabytes in the default configuration.
|
||||
For use in low-memory environments (e.g. running on your DSL router), you can
|
||||
decrease USERS and undefine OUTPACKETQ_LEN in user.h without any ill conse-
|
||||
quence, assuming at most one client will be connected at any time. A small
|
||||
DNSCACHE_LEN is still advised, preferably 2 or higher, however you can also
|
||||
undefine it to save a few more kilobytes.
|
||||
|
||||
|
||||
PERFORMANCE:
|
||||
|
||||
This section tabulates some performance measurements. To view properly, use
|
||||
a fixed-width font like Courier.
|
||||
|
||||
Measurements were done in protocol 00000500 with lazy mode unless indicated
|
||||
otherwise. Upstream encoding always Base64.
|
||||
Upstream/downstream throughput was measured by scp'ing a file previously
|
||||
read from /dev/urandom (i.e. incompressible), and measuring size with
|
||||
"ls -l ; sleep 30 ; ls -l" on a separate non-tunneled connection. Given the
|
||||
large scp block size of 16 kB, this gives a resolution of 4.3 kbit/s, which
|
||||
explains why many values are exactly equal.
|
||||
Ping round-trip times measured with "ping -c100", presented are average rtt
|
||||
and mean deviation (indicating spread around the average), in milliseconds.
|
||||
|
||||
|
||||
Situation 1:
|
||||
Laptop -> Wifi AP -> Home server -> DSL provider -> Datacenter
|
||||
iodine DNS "relay" bind9 DNS cache iodined
|
||||
|
||||
downstr. upstream downstr. ping-up ping-down
|
||||
fragsize kbit/s kbit/s avg +/-mdev avg +/-mdev
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
iodine -> Wifi AP :53
|
||||
-Tnull (= -Oraw) 982 39.3 148.5 26.7 3.1 26.6 3.0
|
||||
|
||||
iodine -> Home server :53
|
||||
-Tnull (= -Oraw) 1174 43.6 174.7 25.2 4.0 25.5 3.4
|
||||
|
||||
iodine -> DSL provider :53
|
||||
-Tnull (= -Oraw) 1174 52.4 200.9 20.3 3.2 20.3 2.7
|
||||
-Ttxt -Obase32 730 52.4 192.2*
|
||||
-Ttxt -Obase64 874 52.4 192.2
|
||||
-Ttxt -Oraw 1162 52.4 192.2
|
||||
-Tcname -Obase32 148 52.4 48.0
|
||||
-Tcname -Obase64 181 52.4 61.1
|
||||
|
||||
iodine -> DSL provider :53
|
||||
wired (no Wifi) -Tnull 1174 65.5 244.6 17.7 1.9 17.8 1.6
|
||||
|
||||
[192.2* : nice, because still 2frag/packet]
|
||||
|
||||
|
||||
Situation 2:
|
||||
Laptop -> (wire) -> (Home server) -> (DSL) -> opendns.com -> Datacenter
|
||||
iodine DNS cache iodined
|
||||
|
||||
downstr. upstream downstr. ping-up ping-down
|
||||
fragsize kbit/s kbit/s avg +/-mdev avg +/-mdev
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
iodine -> opendns.com :53
|
||||
-Tnull -L1 (lazy mode) 230 - - 404.4 196.2 663.8 679.6
|
||||
(20% lost) (2% lost)
|
||||
|
||||
-Tnull -L0 (legacy mode) 230 5.6 7.4 197.3 4.7 610.8 323.5
|
||||
|
||||
[Note: Throughput measured over 300 seconds to get better resolution]
|
||||
|
||||
|
||||
Situation 3:
|
||||
Laptop -> Wifi+vpn / wired -> Home server
|
||||
iodine iodined
|
||||
|
||||
downstr. upstream downstr. ping-up ping-down
|
||||
fragsize kbit/s kbit/s avg +/-mdev avg +/-mdev
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
wifi + openvpn -Tnull 1186 183.5 611.6 5.7 1.4 7.0 2.7
|
||||
|
||||
wired -Tnull 1186 685.9 2350.5 1.3 0.1 1.4 0.4
|
||||
|
||||
|
||||
Performance is strongly coupled to low ping times, as iodine requires
|
||||
confirmation for every data fragment before moving on to the next. Allowing
|
||||
multiple fragments in-flight like TCP could possibly increase performance,
|
||||
but it would likely cause serious overload for the intermediary DNS servers.
|
||||
The current protocol scales performance with DNS responsivity, since the
|
||||
DNS servers are on average handling at most one DNS request per client.
|
||||
|
||||
|
||||
PORTABILITY:
|
||||
|
||||
|
|
|
@ -83,6 +83,12 @@ Server sends:
|
|||
Server may disregard this option; client must always use the downstream
|
||||
encoding type indicated in every downstream DNS packet.
|
||||
|
||||
l or L: Lazy mode, server will keep one request unanswered until the
|
||||
next one comes in. Applies only to data transfer; handshake is always
|
||||
answered immediately.
|
||||
i or I: Immediate (non-lazy) mode, server will answer all requests
|
||||
(nearly) immediately.
|
||||
|
||||
Probe downstream fragment size:
|
||||
Client sends:
|
||||
First byte r or R
|
||||
|
@ -160,6 +166,39 @@ The server response to Ping and Data packets is a DNS NULL type response:
|
|||
If server has nothing to send, data length is 0 bytes.
|
||||
If server has something to send, it will send a downstream data packet,
|
||||
prefixed with 2 bytes header as shown above.
|
||||
|
||||
|
||||
"Lazy-mode" operation
|
||||
=====================
|
||||
|
||||
Client-server DNS traffic sequence has been reordered to provide increased
|
||||
(interactive) performance and greatly reduced latency.
|
||||
|
||||
Idea taken from Lucas Nussbaum's slides (24th IFIP International Security
|
||||
Conference, 2009) at http://www.loria.fr/~lnussbau/tuns.html. Current
|
||||
implementation is original to iodine, no code or documentation from any other
|
||||
project was consulted during development.
|
||||
|
||||
Server:
|
||||
Upstream data is acked immediately*, to keep the slow upstream data flowing
|
||||
as fast as possible (client waits for ack to send next frag).
|
||||
|
||||
Upstream pings are answered _only_ when 1) downstream data arrives from tun,
|
||||
OR 2) new upstream ping/data arrives from client.
|
||||
In most cases, this means we answer the previous DNS query instead of the
|
||||
current one. The current query is kept in queue and used as soon as
|
||||
downstream data has to be sent.
|
||||
|
||||
*: upstream data ack is usually done as reply on the previous ping packet,
|
||||
and the upstream-data packet itself is kept in queue.
|
||||
|
||||
Client:
|
||||
Downstream data is acked immediately, to keep it flowing fast (includes a
|
||||
ping after last downstream frag).
|
||||
|
||||
Also, after all available upstream data is sent & acked by the server (which
|
||||
in some cases uses up the last query), send an additional ping to prime the
|
||||
server for the next downstream data.
|
||||
|
||||
|
||||
======================================================
|
||||
|
|
15
src/common.c
15
src/common.c
|
@ -333,3 +333,18 @@ errx(int eval, const char *fmt, ...)
|
|||
}
|
||||
#endif
|
||||
|
||||
|
||||
int recent_seqno(int ourseqno, int gotseqno)
|
||||
/* Return 1 if we've seen gotseqno recently (current or up to 3 back).
|
||||
Return 0 if gotseqno is new (or very old).
|
||||
*/
|
||||
{
|
||||
int i;
|
||||
for (i = 0; i < 4; i++, ourseqno--) {
|
||||
if (ourseqno < 0)
|
||||
ourseqno = 7;
|
||||
if (gotseqno == ourseqno)
|
||||
return 1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
|
|
@ -88,6 +88,7 @@ struct query {
|
|||
char name[QUERY_NAME_SIZE];
|
||||
unsigned short type;
|
||||
unsigned short id;
|
||||
unsigned short iddupe; /* only used for dupe checking */
|
||||
struct in_addr destination;
|
||||
struct sockaddr from;
|
||||
int fromlen;
|
||||
|
@ -121,4 +122,6 @@ void errx(int eval, const char *fmt, ...);
|
|||
void warnx(const char *fmt, ...);
|
||||
#endif
|
||||
|
||||
int recent_seqno(int , int);
|
||||
|
||||
#endif
|
||||
|
|
Loading…
Reference in New Issue