Centroid.EU Blog
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November 11th, 2013
I have written a small daemon that changes the outgoing TTL on a FreeBSD
host. It's a covert steganographic channel. When a bit is set the TTL
is 65 and when it's 0 the TTL is 64. On the receiving end of a ping then
perhaps you can make out the bits of a message:
jupiter$ ping -i 10 io.solarscale.de
PING io.solarscale.de (78.47.14.22): 56 data bytes
64 bytes from 78.47.14.22: icmp_seq=0 ttl=53 time=15.691 ms
64 bytes from 78.47.14.22: icmp_seq=1 ttl=53 time=16.608 ms
64 bytes from 78.47.14.22: icmp_seq=2 ttl=54 time=14.907 ms
64 bytes from 78.47.14.22: icmp_seq=3 ttl=54 time=15.247 ms
64 bytes from 78.47.14.22: icmp_seq=4 ttl=53 time=15.183 ms
64 bytes from 78.47.14.22: icmp_seq=5 ttl=53 time=16.017 ms
64 bytes from 78.47.14.22: icmp_seq=6 ttl=53 time=16.465 ms
64 bytes from 78.47.14.22: icmp_seq=7 ttl=54 time=15.134 ms
64 bytes from 78.47.14.22: icmp_seq=8 ttl=53 time=18.659 ms
64 bytes from 78.47.14.22: icmp_seq=9 ttl=53 time=15.542 ms
64 bytes from 78.47.14.22: icmp_seq=10 ttl=54 time=15.176 ms
64 bytes from 78.47.14.22: icmp_seq=11 ttl=54 time=16.411 ms
64 bytes from 78.47.14.22: icmp_seq=12 ttl=53 time=15.418 ms
64 bytes from 78.47.14.22: icmp_seq=13 ttl=54 time=15.438 ms
64 bytes from 78.47.14.22: icmp_seq=14 ttl=53 time=15.388 ms
64 bytes from 78.47.14.22: icmp_seq=15 ttl=53 time=15.918 ms
64 bytes from 78.47.14.22: icmp_seq=16 ttl=53 time=15.306 ms
64 bytes from 78.47.14.22: icmp_seq=17 ttl=53 time=15.347 ms
Notice how the TTL changes here. If it's 54 then the original TTL was 65,
so 1 bit. So what was gathered here was 001100010011010000. Eventually
I'd like to write a client to record this. But I'm gonna cheat for now
and give you the source code.
I just give greetings and peace wishes but with a bit of coding it could
be changed to something very creative!
0 comments
What's happening here?
November 11th, 2013
I think the medias need to step back a bit. We all know that the US is spying
on us but we don't need to be spoon-fed the paranoia. It's causing illogical
decisions (firewalled europe anyone?) on parts of big powerful corporations
who see opportunity to take away everyones freedom. Let's get off this
paranoid horses back! I love freedom personally.
0 comments
talk(1) patch to display timestamps
November 9th, 2013
I have written a small patch to talk(1) as found in FreeBSD (yes for a change!)
to display timestamps when someone wrote a line. It's a little buggy but it
works.
Thanks goes to Dylan who I've been talk(1)ing with and gave me the idea.
0 comments
Smithing tools to understand code
November 8th, 2013
Yesterday I looked at the traceroute(8) source code in order to look for
attack vectors. I came out empty handed. But I smithed a tool for my
work that can be reused later I think.
This tool helped me overcome reading the function print_exthdr() better and
determining it was safe. Not many people admit to doing this kinda stuff but
I think I'll leave this to the next person that doubts OpenBSD's traceroute.c.
I'm not ashamed at all! Should I be?
0 comments
Facilities and Priorities in syslog
November 4th, 2013
We had this problem in that we didn't know what facility a certain program was
syslogging to, so we straced it (in linux), check a sample here:
root@raspberrypi:~# tail /tmp/blah.out
read(1, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\0\0\0\1\0\0\0\0"..., 4096) = 118
_llseek(1, -6, [112], SEEK_CUR) = 0
read(1, "\nUTC0\n", 4096) = 6
close(1) = 0
munmap(0xb6caf000, 4096) = 0
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 1
connect(1, {sa_family=AF_FILE, path="/dev/log"}, 110) = 0
send(1, "<13>Nov 3 00:00:14 pi: hi", 26, MSG_NOSIGNAL) = 26
close(1) = 0
exit_group(0) = ?
That was produced with the input "strace -o blah.out logger hi". So syslog
logs a number inside <> at the beginning to indicate what facility and priority
it is. It's sorta a code. So I wrote the following
BSD program
to convert the number into their respective fac and pri. Enjoy!
root@raspberrypi:/tmp# ./facility 13
facility: (8)user, priority: (5)notice
For administrivia, how would you speed up this program? Take a look at
/usr/include/syslog.h and think binary search.
0 comments
Jupiter (computer) now on Radeon
November 3rd, 2013
After 3.5 years of Nvidia, the box is now running a low to medium end
Sapphire Radeon HD5450 card. I'm saving a ton of electricity with this
card too! And OpenBSD is fast again! Wonders!
0 comments
Fast Hellos are on
November 1st, 2013
Yesterday I turned on fast hellos on my OSPF setup. This is what venus'
ospfd.conf file looks like now:
... some cut ...
area 0.0.0.0 {
interface gif0 {
router-priority 1
metric 1
router-dead-time 40
auth-type simple
auth-key $password
router-dead-time minimal
fast-hello-interval msec 333
}
interface gif1 {
router-priority 5
metric 10
router-dead-time 40
auth-type simple
auth-key $password
router-dead-time minimal
fast-hello-interval msec 333
}
}
Notice gif0 has a lower metric than gif1, fast-hello-interval time is 333 msecs.Which is also default so it needn't be there. The "router-dead-time minimal"
causes fast hellos to go on. So when I watch the packets on gif1 which isn't
used for traffic I see:
# netstat -nw 1 -I gif1
gif1 in gif1 out total in total out
packets errs packets errs colls packets errs packets errs colls
200827 0 209273 0 0 75406364 0 80678099 0 0
3 0 3 0 0 29 0 29 0 0
3 0 3 0 0 22 0 22 0 0
...
exactly 3 packets per second in either direction. I suspect now that when
my LTE fritz!box crashes again that the failover to the gif1 link will be
next to instant.
0 comments
OpenBSD 5.4 released
November 1st, 2013
You can now download OpenBSD 5.4 from your favourite OpenBSD FTP mirror.
I usually use ftp.eu.openbsd.org in europe but if I was in north america
I'd use ftp.openbsd.org. Congratulations to the OpenBSD team for yet another
great release!
0 comments
Centroid blog now available in CVS
November 1st, 2013
I have decided to open source the PHP behind this blog. It's all about
letting go and showing the innards isn't it? :-)
Anyhow here
are the sources. This PHP source code has never seen anyone's eyes but mine
before this. Perhaps it's not great but it makes this blog the way it is.
0 comments
A tiny blip on the W commit log screen
October 30th, 2013
Wildcarddnsd didn't get much commit time this year. But this time there
was something. I committed support for Raspberry Pi running raspbian.
That's gotta count for something, however small. Have fun with it!
0 comments
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