just observed a sweep from IP 66.186.59.50, "ircu.krypt.com", looking into port 1137. a bit of news suggests this is a vulnerability search. the signal is coming from an IRC line, port 6667. they must be looking at IRC logs and sweeping those addresses, since i've actually been on IRC in the last couple of weeks (and last night).
another thing, i also saw (for the first time) some nonreciprocated requests for port 34268 while skype was turned off. looking for a relay? i scanned the source and it doesn't actually seem to be a skype host, though maybe i waited too long, after they had turned it off. instead, they actually had unfiltered, closed ports 5800/5900, which are used for remote desktop viewing. also, no clue as to the OS, so i don't know what it actually is. another user? something else? it's another comcast host, presumably another user, but who knows?
i'll check it out again later.
Sunday, May 09, 2010
Thursday, May 06, 2010
internet metaphors
okay, this is kind of dumb, bust since i haven't learned anything new lately, it's all i've got.
actually, i thought of this a few days ago. i was at the taekwondojang, thinking about how the classes work. (almost) every class starts the same way, regardless of who the teacher is, with a set of warmup exercises. different teachers will count a little differently, faster or slower maybe, but everyone does the same exercises. next, we start going through techniques in the lineup, and the first is always "riding stance to the left, left-hand punch". next technique will usually be "step forward front stance, low-section guarding block".
so, up to this point things are the same no matter who the instructor is, no matter what the rest of the class is going to be about. from here, things are still predictable to a point - after the low-section blocks, we'll probably do mid and high section blocks, maybe with a punch after the mid-section blocks. next, we go to fighting stance and start doing kicks, with front kick and punch first, round kick and roundhouse punch next, then sidekick with knifehand strike. it gets less and less predictable after this.
by the end of the lineup, we've probably done a couple of techniques that haven't come up in at least a week or so in other lineups. then, the rest of class will focus on a few specific techniques in some permutation of the "find a partner" game.
what this has to do with the internet is that i realized that the course of a given class could be analogized directly to a traceroute, assuming a single start location. the first few steps away from the local host are the same every time, but depending on the destination eventually the paths will diverge. the warmup and starting techniques are like the local network path out, the later techniques are like the area network, where there are a few possible large routers to choose from, and the remainder of class is like the ultimate path and network destination. kind of.
really, you could apply this structure to all sorts of things, where the first few steps are the same, but eventually there's a divergence and then different paths to disparate destinations. in a lot of ways that's how the brain works, how distribution networks of all kinds operate, etc.
like i said, not too interesting, but it's all i've got for now.
actually, i thought of this a few days ago. i was at the taekwondojang, thinking about how the classes work. (almost) every class starts the same way, regardless of who the teacher is, with a set of warmup exercises. different teachers will count a little differently, faster or slower maybe, but everyone does the same exercises. next, we start going through techniques in the lineup, and the first is always "riding stance to the left, left-hand punch". next technique will usually be "step forward front stance, low-section guarding block".
so, up to this point things are the same no matter who the instructor is, no matter what the rest of the class is going to be about. from here, things are still predictable to a point - after the low-section blocks, we'll probably do mid and high section blocks, maybe with a punch after the mid-section blocks. next, we go to fighting stance and start doing kicks, with front kick and punch first, round kick and roundhouse punch next, then sidekick with knifehand strike. it gets less and less predictable after this.
by the end of the lineup, we've probably done a couple of techniques that haven't come up in at least a week or so in other lineups. then, the rest of class will focus on a few specific techniques in some permutation of the "find a partner" game.
what this has to do with the internet is that i realized that the course of a given class could be analogized directly to a traceroute, assuming a single start location. the first few steps away from the local host are the same every time, but depending on the destination eventually the paths will diverge. the warmup and starting techniques are like the local network path out, the later techniques are like the area network, where there are a few possible large routers to choose from, and the remainder of class is like the ultimate path and network destination. kind of.
really, you could apply this structure to all sorts of things, where the first few steps are the same, but eventually there's a divergence and then different paths to disparate destinations. in a lot of ways that's how the brain works, how distribution networks of all kinds operate, etc.
like i said, not too interesting, but it's all i've got for now.
Saturday, May 01, 2010
local network
i mentioned earlier that i had tried the traceroute scan on the institute's local network. i had, but it was so dense that trying to look at the graph caused nmap to die. i did it again today, but carefully collapsed the densest nodes, so i could see the 'backbone' of the network. what i saw was interesting, and implies that my thinking was kind of mistaken.
i had been thinking that i would be looking at the institute network - that the institute must have set up a local 192.168 network within the Harvard system, and that by scanning that prefix (up to 192.168.36.255, which was where addresses seemed to stop existing) i would get back a picture of the institute network. instead, i saw that the scan went out into the Harvard 128.103 network, then back into the local network. I think this may have been scanning into systems outside of the Institute, and except for the hosts themselves (on the other side of the Harvard nodes) i got back no IP info, so couldn't see the structure. what i could see was that hosts with names on my side of the Harvard nodes all were associated explicitly with the institute (having the institute initials in the hostname), while those on the other side did not.
but, from institute out, i could see that there's a single way out of the institute network, connecting to two nodes both named something like 'core' (i don't have the scan here at home to look at). one of these led into many, many other private network hosts along those blind pathways, and so did the other, along with leading to the node that exits the system into NOX, or level3, or wherever the localhost is pointing.
so, point is, a traceroute to another address with the same prefix as the localhost may not traverse only other hosts with the same prefix. i had assumed that the 192.168 network was somehow self contained, that any hosts i saw within it must be linked through other 192.168 hosts. apparently this isn't necessarily how it works. i have more to learn.
(actually, i had noticed this last week, in scanning my comcast prefix - i found other systems separated from me by large interchanges with different prefixes (but prefixes common to other interchanges), but themselves having the same prefix as mine. i didn't understand it at the time, but forgot about it. this bugged me more, probably because of the 'private network' label attached to 192.168.)
i had been thinking that i would be looking at the institute network - that the institute must have set up a local 192.168 network within the Harvard system, and that by scanning that prefix (up to 192.168.36.255, which was where addresses seemed to stop existing) i would get back a picture of the institute network. instead, i saw that the scan went out into the Harvard 128.103 network, then back into the local network. I think this may have been scanning into systems outside of the Institute, and except for the hosts themselves (on the other side of the Harvard nodes) i got back no IP info, so couldn't see the structure. what i could see was that hosts with names on my side of the Harvard nodes all were associated explicitly with the institute (having the institute initials in the hostname), while those on the other side did not.
but, from institute out, i could see that there's a single way out of the institute network, connecting to two nodes both named something like 'core' (i don't have the scan here at home to look at). one of these led into many, many other private network hosts along those blind pathways, and so did the other, along with leading to the node that exits the system into NOX, or level3, or wherever the localhost is pointing.
so, point is, a traceroute to another address with the same prefix as the localhost may not traverse only other hosts with the same prefix. i had assumed that the 192.168 network was somehow self contained, that any hosts i saw within it must be linked through other 192.168 hosts. apparently this isn't necessarily how it works. i have more to learn.
(actually, i had noticed this last week, in scanning my comcast prefix - i found other systems separated from me by large interchanges with different prefixes (but prefixes common to other interchanges), but themselves having the same prefix as mine. i didn't understand it at the time, but forgot about it. this bugged me more, probably because of the 'private network' label attached to 192.168.)
Wednesday, April 28, 2010
traceroute scanning
something that's lots of fun to do is to scan a network with a traceroute command. what you get back is a (relatively) complete picture of the network connecting all the hosts with the specified prefix. depending on where you point it, it can be very, very big.
like i mentioned earlier, i know which node it is that stands between me and several routers that connect to different parts of the Boston internet. one of those routers goes to NOX, and another one to other residential (i think) comcast accounts. if i point the traceroute scan at a comcast node that's relatively nearby, and that contains the same IP prefix as mine (20 bits is reasonable and doesn't give back 65 thousand possible hosts), i get back a nice, complex picture of a network extending from here and across Boston, and across MA to CT, VT, and the MA-NY border.
i tried the same thing on the private 192.168 network at the institute, and got back something similar, and actually much denser (which makes sense, all hosts within the network have the same prefix, so i could get them all in one big shot, but the comcast network was relatively sparser, and seemed to have same-prefix hosts separated by nodes with different prefixes, which i don't understand...). since it's a single institution, it's organized differently - there are nodes for different users, but mainly the network divisions are more functional, with databases in one place, outgoing servers in another, administrative here, labs there. the comcast network looked much more regional, with a Hartford node, others (i get all these new englandy names confused, they all sound like Westly or Chestford or something like that).
ok, need to step back now and get more acquainted with the specifics rather than just playing with these toys...
like i mentioned earlier, i know which node it is that stands between me and several routers that connect to different parts of the Boston internet. one of those routers goes to NOX, and another one to other residential (i think) comcast accounts. if i point the traceroute scan at a comcast node that's relatively nearby, and that contains the same IP prefix as mine (20 bits is reasonable and doesn't give back 65 thousand possible hosts), i get back a nice, complex picture of a network extending from here and across Boston, and across MA to CT, VT, and the MA-NY border.
i tried the same thing on the private 192.168 network at the institute, and got back something similar, and actually much denser (which makes sense, all hosts within the network have the same prefix, so i could get them all in one big shot, but the comcast network was relatively sparser, and seemed to have same-prefix hosts separated by nodes with different prefixes, which i don't understand...). since it's a single institution, it's organized differently - there are nodes for different users, but mainly the network divisions are more functional, with databases in one place, outgoing servers in another, administrative here, labs there. the comcast network looked much more regional, with a Hartford node, others (i get all these new englandy names confused, they all sound like Westly or Chestford or something like that).
ok, need to step back now and get more acquainted with the specifics rather than just playing with these toys...
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