o/

my question is, how do I pair up the ip addresses (actual source) with the port they're attempting to connect under (13211)

@rlemon Your question is full of problem-specific jargon that makes it very difficult to understand. You're going to have to fall back to first principles to explain this more simply (which may also help you understand it and answer your own question).

First let's review what ssh -R even does (or what you think it does).

no clue, this isn't my domain

I'm attempting to just map ip's to ports

First, SSH is built on top of TCP. Every TCP connection has a source IP, source port, destination IP, and destination port. The connection is initially established by the source making an outbound connection to the destination IP:Port. The source port is used when the destination is sending packets back to the source on the established connection.

my understanding was I was tunneling port 13211:localhost to 13211:remotehost

(and tbf, for my actual application, that seems to work as expected)

Yeah, but to really understand this, you have to understand exactly what it means to tunnel something. The SSH connection establishes an encrypted TCP socket between source and destination. Then, once the remote port forward is established, the SSH daemon on the destination (the SSH server) opens up a new port on localhost:13211, and any connections to localhost:13211 get forwarded (copied) through the tunnel to the localhost:13211 port on the source (client).

okay, yea that makes sense.

instructions too complex, hand stuck in jar

now I have to find instructions on how to free my hand

@rlemon So I'm still not quite sure what your goal is. Map what IPs to what ports?

@allquicatic my goal is that I have N clients connect with that ssh structure, all with different mapped ports.

Are you trying to, from the perspective of the server, determine which remote client IP currently providing a remote forwarded port maps to which localhost:XXXX port on the server?

I want to obtain their ip given my list of listening ports

@allquicatic just get the actual ip address

the only place I know those exist is the iptable

@rlemon So, to answer my question, "yes", then -- right?

yes

just making sure we're on the same page. clearly this isn't my forte

OK. That's information that the SSH server has internally, so there should be some way to get that out to the user... hmmm

programmers shouldn't be asked to do this stuff :P

rlemon I didnt see your car here either

@allquicatic so from my testing, I can see the ports connected to localhost when I run netstat

and when I run iptstate I can see my own ip (testing device)

but the port listed next to it isn't the port I would have expected

hey rlemon do you know how tcp works in general?

always lists the ports under 127.0.0.1

sudo lsof -i -n | egrep '\<sshd\>'

run that on the server

been at this for a few hours. seen most of those already

I am, it lists everything as 127.0.0.1:port

@rlemon what you're seeing is the source port of your connections to the remote port on the server.

source ports are determined pseudorandomly

is there any way to take that and determine which destination(?) port I am pointing at?

end goal (if it isn't clear): I have a list of ports I'm expecting clients to connect on, I just want to fill it with their ips

if I'm barking up the wrong tree, stop me now

@rlemon The problem is, the only place where the information "associating" any given localhost:port to a given SSH client IP, is stored, is within the sshd's memory.

hrm

Your last resort may be to parse SSHD's logs, and put it on maximum verbosity.

It'll probably write something to the log when you remote port forward.

so the clients are programmed to connect using a specific local port? well that's tough because if you have multiple computers on your LAN, the router or modem or gateway might be assigning different public ports than the ones you specify locally

Try this on the server: go into /etc/ssh/sshd_config and look for any settings about debugging, verbosity, etc. and set it to maximum

then restart sshd, then check the logs when you initiate a remote port forward connection

and see what it writes to the log - then see if you can parse that out using regex or something to build your "map"

I assume restarting sshd kills all active connections?

because yea, can't do that

actually...

because if you think about it, several computers on your LAN trying to communicate with a remote host might choose the same local port. if the gateway did not assign unique ports you'd had 4 different computers looking like 123.234.234.23:58 . where should the incoming traffic go if there's 4 of those?

@CausingUnderflowsEverywhere I have no idea what you're talking about.

@rlemon depends on the version of your OS and SSHD and such, but at least on recent Ubuntu and RHEL, both reload and restart of sshd do not kill active connections

I'm not being rude by ignoring you, just struggling with this in general so trying to focus on one person

reload is always safe and will never kill connections

restart doesn't, either, on at least Ubuntu 14.04 and later

Im going to make an mspaint picture out of it

it's some kind of magic

/me looks in

@allquicatic 12.04 new enough?

@rlemon ack, don't know

@rlemon OH THE TABLES HAVE TURNED \o/

if you have another server to test it on that's 12.04, I would try it there

/me reads backl;og

I'm not 100% certain that sshd restart on 12.04 won't bounce connections

@allquicatic none of this will be an issue in January when the process is complete and I can take devices offline :(

so If it is going to cause downtime I'm leaning towards just moving on

@rlemon welp, time to fire up a 12.04 VM, SSH to it, and restart sshd

(gonna test on 12.04 anyway)

actually a reload of the config might be enough to update the verbosity without restarting the daemon

reload just tells it to reparse its config but doesn't kill and restart the process

just pointing that out, I can just walk away from this for a better solution (the client sends me their ip)

restart kills the process, but it somehow keeps the connections alive during it through some incredible magic

if it's a new enough version

yeah on Ubuntu 12.04 you can try doing a reload on sshd first

that'll definitely be safe

from my understanding you want to set the local ports in clients to static ones, like assign specific ones, so then your ssh server knows who's who because of the port they connect on, but unfortunately that's not possible if the gateway maps ports as seen on the public side of the network

@rlemon

none of that makes sense to me

you're trying to explain big o to a vb developer

a gateway might be a router or modem

amazon.de/gp/product/B00I6EJOX6

well it doesn't have to make sense, anyone can correct me if Im wrong but your server might not see the actual port number traffic is coming from. that's all you need to know

I learned of these today. I needed them two years ago.

reloading ssh, crossing fingers, expecting the worst (I am a lemon)

IM SO STRESSED OUT BYE GUYS

@CausingUnderflowsEverywhere grab a beer and watch some youtube

there are some nice woodworking channels I can recommend, very soothing :D

@Hennes Für größere Ansicht Maus über das Bild ziehen

Adchkeschafturgënschisch

Das ist ja klar

I did not realise that the webpage was in German.

What am I looking at? An HDMI plug who hates me very much?

@ThatBrazilianGuy @Hennes is Dutch not German IIRC

It is a virtual monitor. PLug in and the computer thinks that you plugged ina monitor.

Needed with some graphics when you want to set a sane resolution, but have no actual monitor connected.

@allquicatic nada :( seeing the same information I saw in iptstate

@rlemon anything happen?

check /var/log/ssh (I don't know the exact path, hit tab and see what's there)

also /var/log/syslog

ahh

E.g. if I boot a laptop with no monitor (lid closed as usual) and I teamviewer in I can only use 640x480 or 800x600.

I was only looking in auth.log

So emulating a monitor is needed

@DavidPostill Tell him that, he linked amazon.de

No amazon.nl. So we dutch use either amazon.de or amazon.co.uk

yea, not seeing anything useful in here

Or amazon.com and add two months shipping time

@allquicatic thanks for the time, I think I'm going to shelve it for now

@CausingUnderflowsEverywhere thanks as well.

@Hennes Neat. What resolution does it go up to?

@Hennes I've got six months shipping time from China.

The one linked seem to do 1080, the 4K version.... well that name gives it away

Oh. Missed that.

For what I needed it I just connected a real 1920x1200 monitor which I did not look at. 24" of space and some power wasted just to be able to properly remote in.

Ah, election times. So much simpler in some countries.

Yipes.

docs.google.com/document/d/…

Cert. Auth lying about dates. And the reaction on that from Mozilla.

If you have WoSign or StartCom certs, better read it.

my god, parents are hard work

my mum has had an android tablet for ages (about 18 mths) but trying to get her used to her new xperia is tough

@rlemon no time I musnt be late

@CausingUnderflowsEverywhere no, since a lot of that is recovery related

@JourneymanGeek ?

Hello power users

Hi!

Which free software open source or not you would recommend to cut and merge video files?

I've a bunch of old .VOB files I would like to cut and merge

Command-line, or GUI?

before converting

Whatever but GUI is always better haha

mediacoder?

Oh and I would like to do this without having to reencode the video! It would take weeks if I were to recode every file to cut and merge

@Bob someone asking on threading on Firefox a few lines up.

For some reason I remember you poking at that.

@JourneymanGeek Not sure I remember that :P

ah. Meh.

@vin Vaguely: you'd want to look at things like OMTC (and APZ?) and service workers

Is there any particular reason you want to know?

@allquicatic Did you ever find me on Allo?

@Bob nope

@allquicatic Do you know if mediacoder can cut the videos without recoding ?

I think you have to use a phone number (?)

@allquicatic ...I thought I used your phone number O_O

Don't you have mine from the messages earlier?