cool.... apparently if I do the firmware upgrade I'll be able to receive as well as send. :-)~MIKE~(-: On Sun, Jul 20, 2014 at 6:17 PM, Michael Havens wrote: > I think I should give you the models of my devices: > the router is a wrt54g and the modem is a pk5000. I did a little more > searching and read that I can change the firmware on the router but if > memory is correct if I screw up it becomes a brick so I need to ask what > the benefits are and if there is another way to do it. I just looked > closely at the router and it is labled as a wireless router and a 4 port > switch. > > :-)~MIKE~(-: > > > On Sat, Jul 19, 2014 at 11:39 AM, Michael Havens wrote: > >> >Why were rules written for the second router but not the first? >> >Is it because it was connected first? Could we write the rules we need? >> >> What I meant was the second was connected to the first. >> >> >> :-)~MIKE~(-: >> >> >> On Sat, Jul 19, 2014 at 11:31 AM, Michael Havens >> wrote: >> >>> > Going the other way, you have no rules to pass >>> > the communication through. >>> >>> Why were rules written for the second router but not the first? Is it >>> because it was connected first? Could we write the rules we need? >>> >>> >>> :-)~MIKE~(-: >>> >>> >>> On Fri, Jul 18, 2014 at 3:34 PM, Gilbert T. Gutierrez, Jr. < >>> mailing-lists@phoenixinternet.net> wrote: >>> >>>> NAT is the reason. The ping is being translated from one network to >>>> another as well as telnet. Going the other way, you have no rules to pass >>>> the communication through. >>>> >>>> Gilbert >>>> >>>> >>>> On 7/18/2014 2:44 PM, Michael Havens wrote: >>>> >>>> so according to your tutorial 192.168.0.x is not on the same subnet as >>>> 192.168.1.x. If that is correct why can I ssh (and ping and telnet....) >>>> from client to host but not host to client? >>>> >>>> :-)~MIKE~(-: >>>> >>>> >>>> On Fri, Jul 18, 2014 at 12:30 PM, Michael Havens >>>> wrote: >>>> >>>>> telnet localhost 22 from the server received no answer from the >>>>> client >>>>> telnet 192.168.1.101 22 from the client received no answer from the >>>>> server >>>>> >>>>> I'll get back to you about the research project >>>>> (and as a private message) >>>>> >>>>> :-)~MIKE~(-: >>>>> >>>>> >>>>> On Fri, Jul 18, 2014 at 6:41 AM, wrote: >>>>> >>>>>> Hello Michael: >>>>>> the 'Net' is a hodgepodge of protocols, all abiding to the 'OSI Layer >>>>>> Model' to work properly (http://en.wikipedia.org/wiki/OSI_model). >>>>>> Troubleshooting your SSH connection should be a fairly simple >>>>>> proposition, because there are only so many moving parts (Three!). >>>>>> As anything under the OSI model, nothing on an upper layer will work >>>>>> unless the necessary components of the lower layer are working. >>>>>> AND you *HAVE* to troubleshoot each layer separately. >>>>>> So how does this go? >>>>>> Well, lets take a look at your SSH problem... >>>>>> 1.- In order for the SSH connection to work you need 3 things: >>>>>> 1.1.- a SSH server, >>>>>> 1.2.- a SSH client and, >>>>>> 1.3.- a TCP/IP connection. >>>>>> *EACH* one of the lines above is a separate project and *HAS* to be >>>>>> addressed as such. >>>>>> Lets cover the basics first, the TCP/IP connection: >>>>>> You *HAVE* to *KNOW* The Mantra: >>>>>> "In order for any 2 devices to establish a TCP connection they have >>>>>> to share a physical link and they need addresses in the same subnet". >>>>>> The statement above is a pretty dense one, and has several >>>>>> implications, number one being: What does "subnet" mean? >>>>>> Another is: what about IPs in different subnets? >>>>>> We'll get there... >>>>>> As there are already several books written (and to be written) about >>>>>> the few lines above, I'll water it down to the bare minimum: >>>>>> The subnet is defined via the netmask, and implies that "ON" parts of >>>>>> the netmask are always equal in all the addresses on a network segment, so: >>>>>> Network: >>>>>> 192.168.0.0/24 or >>>>>> 192.168.0.0 with netmask 255.255.255.0 means that >>>>>> *ALL* the addresses in *THIS* network are going to look like >>>>>> 192.168.0.${SOMETHING_ELSE} >>>>>> '192.168.0' is the "Network", and "${SOMETHING_ELSE}" is the "Host". >>>>>> You can not use "Host 0" (because that defines the network) and you >>>>>> can not use the highest number (255) because that's the 'broadcast address'. >>>>>> Which means that any '/24" (slash 24) network can address 254 >>>>>> 'hosts'. >>>>>> Network: >>>>>> 192.168.0.0/16 or >>>>>> 192.168.0.0 with netmask 255.255.0.0 means that >>>>>> *ALL* the addresses in *THIS* network are going to look like >>>>>> 192.168.${SOMETHING_ELSE}.${SOMETHING_ELSE} >>>>>> '192.168' is the "Network", and "${SOMETHING_ELSE}.${SOMETHING_ELSE}" >>>>>> is the "Host". >>>>>> You can not use "Host 0.0" (because that defines the network) and you >>>>>> can not use the highest number (255.255) because that's the 'broadcast >>>>>> address'. >>>>>> Which means that any '/16" (slash 16) network can address 65534 >>>>>> 'hosts'. >>>>>> The reason why '255' is the highest number is because IPv4 addresses >>>>>> (and netmasks) are represented in memory in 4 bytes, each number one byte. >>>>>> Bytes are 8 bits, but that's a different book that you need to read >>>>>> too, lets move on with the network. >>>>>> Things get pretty interesting (and math pretty convoluted) when you >>>>>> define networks like 192.168.127.0/25 >>>>>> If yo want to see all variations, you can be lazy (like me) and run: >>>>>> ipcalc 192.168.0.127/25 >>>>>> Finally, "Netmasks" are a patch to the first defined (and >>>>>> shortsighted) 'Address Type' as class A,B,C or D, but I'll let you research >>>>>> that yourself. >>>>>> >>>>>> Well, that's all good, but how do you talk to other addresses?, I >>>>>> talk to google.com... >>>>>> That's a valid question, but >>>>>> 1.- it is not part of *THIS* SSH problem and >>>>>> 2.- you don't 'talk to google'. >>>>>> We'll talk more about how devices find each other in a network down >>>>>> below, but in order to talk to devices outside your network you need the >>>>>> 'Routing Protocol' (implemented at [SURPRISE!] 'the router') which is >>>>>> nothing else than a table of rules stating 'this IP goes that way'. In >>>>>> your case, all addresses go the same place (the router) so the router >>>>>> becomes the 'Default Gateway'. As to resolve google, you need the DNS, but >>>>>> you knew that... :) >>>>>> >>>>>> Now that we know what an IP address is, lets move on to the "Physical >>>>>> Link". >>>>>> Well, a cable will do... >>>>>> In the wireless world, the "Association" is the link. >>>>>> And how do you validate that? >>>>>> iwconfig will tell you what (if anything) you are associated to. No >>>>>> association, no link, no connection, no SSH. >>>>>> ifconfig will tell you what (if anything) you are wired to. No wire, >>>>>> no link, no connection, no SSH. >>>>>> Ain't that simple? ;-) >>>>>> So we have a link... >>>>>> And we have IP addresses in the same subnet. >>>>>> So we are connected!!! 8-) >>>>>> Not so fast Armando!!! >>>>>> The fact that your addresses match is not necessarily a validation, >>>>>> because each computer may be connected to a different router providing the >>>>>> same NAT(ed) address! >>>>>> NAT? >>>>>> Yes NAT (Network Address Translation protocol), but that's yet >>>>>> another book, so lets water it down: >>>>>> NAT is the protocol that allows you to have an 'outside visible >>>>>> address' and an 'inside invisible network' in a router. >>>>>> NAT (as Netmask) was implemented mainly to alleviate the IPv4 >>>>>> shortage address because of the 'class A,B,C or D' mistake, but as a >>>>>> byproduct, you can 'hide' behind it, which provides some level of security. >>>>>> How you hide is yet another bookshelf and essentially means that you >>>>>> cannot access devices 'behind the router' unless the device initiates the >>>>>> connection first, and that's how you raise a WEB site from 'behind the >>>>>> router' and why you can SSH from 'inside to outside the router' but not the >>>>>> other way around, so lets move on... >>>>>> So, how do we know that we are connected to the same router? >>>>>> Ah, glad you asked: >>>>>> ARP! >>>>>> Or Address Resolution Protocol. >>>>>> *ALL* data transmission is done at OSI layer 2. >>>>>> Quick implementation manual: >>>>>> OSI layer 1: Cable or association. >>>>>> OSI layer 2: MAC address. >>>>>> OSI layer 3: IP address. >>>>>> Your network doesn't know (and doesn't care) about IP addresses. The >>>>>> IP address is there to resolve the MAC address. >>>>>> When you say: >>>>>> ping 192.168.0.1 >>>>>> that generates a 'who has' request from the ARP protocol. >>>>>> That request is broadcasted to anyone on the physical link (OSI layer >>>>>> 1) >>>>>> The device with the IP address interrogated by 'who has' answers with >>>>>> its MAC address. >>>>>> This IP/MAC address pair is then saved to the ARP table. >>>>>> >From there on (and even though the IP address goes along in the >>>>>> TCP/IP header) all transmissions are sent to the MAC address. >>>>>> But then again, how do you know that your 2 boxes are talking to the >>>>>> same router? >>>>>> arp -n|grep 192.168.1.1 >>>>>> Same MAC? >>>>>> Same box. >>>>>> Different MAC? >>>>>> Same Michael... ;-) >>>>>> What do we know so far? >>>>>> Well, we know something about line 3 of the very first paragraph. >>>>>> What about line 2? >>>>>> Type >>>>>> which ssh >>>>>> You have it or not, and you know what to do, so lets move to line 1. >>>>>> We now need to troubleshoot the SSH server. >>>>>> Well, that boils down to 2 things, it is working or not... >>>>>> You *KNOW* that the SSH server is 'listening' (although not >>>>>> necessarily working) when you can connect to the 'port' >>>>>> Port? >>>>>> Yeah, port... >>>>>> Lets move on up in the OSI model to the application layer. >>>>>> In order to establish a TCP connection you need an IP connection and >>>>>> a port (or a socket and a port) >>>>>> The port is to the application what the IP address is to the MAC. >>>>>> So if the port is listening, the application is awake. >>>>>> And how do we know? >>>>>> There are only 975143684 possible ways to validate a 'port is open' >>>>>> (or listening) but I am a simple boring guy, so I do: >>>>>> telnet localhost 22 >>>>>> I either get an answer or not. >>>>>> If I get an answer, then we are most likely all good, but if I don't >>>>>> get an answer then the ramifications are staggering and I'm not even going >>>>>> to think about it. >>>>>> In order to check that the other port listens then you: >>>>>> telnet ${REMOTE} 22 >>>>>> Again, we either get an answer or not. And the 'not' means another >>>>>> Sunday drive to the library... >>>>>> Finally, why 22? >>>>>> Because that's the SSH port and it is defined in the configuration >>>>>> file, which you can change to further complicate your (or someone else's) >>>>>> life. >>>>>> But who and where defined 22 as the SSH port? >>>>>> grep -i ssh /etc/services >>>>>> And who wrote /etc/services? >>>>>> http://www.iana.org/ >>>>>> And how do I know all this crap? >>>>>> Because I finished LFS!!!! ;-) >>>>>> I hope you see everything now as clear as mud. >>>>>> Keep this message handy, you'll need to read it several times... >>>>>> Keep in mind that what I have written here is a GROSS >>>>>> oversimplification of several bookshelves contained in several buildings >>>>>> and written along several decades all over the World, it's free advice, you >>>>>> can't sue me... :) >>>>>> And always remember: >>>>>> For every question there exists a simple, direct and wrong answer. >>>>>> if you have any question, >>>>>> you will get any answer... >>>>>> ET >>>>>> PS: Research project: >>>>>> Why doesn't 'ping' use a port? >>>>>> Why is 'ping' 'setuid(ed)' >>>>>> What are 'routable' networks? >>>>>> What are 'non-routable' networks? >>>>>> What does it mean if you get and IP address like 169.254.0.0/16 >>>>>> Why do you always have a 127.0.0.1 address in your boxes? >>>>>> Who defines (and where are the documents that define) all these >>>>>> protocols? (RFC anyone?) >>>>>> >>>>>> >>>>>> Michael Havens writes: >>>>>> >>>>>>> okay, so I bought a used computer to do Linux from scratch on. Well, >>>>>>> I'm >>>>>>> going to ssh from my primary computer to the new computer but got a >>>>>>> 'Connection timed out' error. After googling for a bit I discovered >>>>>>> ufw was >>>>>>> to blame. >>>>>>> after I disabled the firewall I could ssh from 192.168.1.101 >>>>>>> to >>>>>>> 192.168.0.4 >>>>>>> the error I got going the other way was the connection timed out >>>>>>> error: >>>>>>> ssh mike@192.168.1.101 >>>>>>> ssh: connect to host 192.168.1.101 port 22: Connection timed out >>>>>>> After googling some more I thought perhaps openssh-server wasn't >>>>>>> installed... but it is. So please.... what is the problem? I verifed >>>>>>> openssh-client is installed but I don't know what it could be. Could >>>>>>> you >>>>>>> help me out? >>>>>>> :-)~MIKE~(-: >>>>>>> >>>>>> --------------------------------------------------- >>>>>> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org >>>>>> To subscribe, unsubscribe, or to change your mail settings: >>>>>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss >>>>>> >>>>> >>>>> >>>> >>>> >>>> --------------------------------------------------- >>>> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org >>>> To subscribe, unsubscribe, or to change your mail settings:http://lists.phxlinux.org/mailman/listinfo/plug-discuss >>>> >>>> >>>> >>>> --------------------------------------------------- >>>> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org >>>> To subscribe, unsubscribe, or to change your mail settings: >>>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss >>>> >>> >>> >> >