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Spammers: they're getting cleverer

M

Mark R

Diamond Member
How much longer before Bayesian statistical filters become useless. I'm getting more and more spams, that contain crap like that below - essentially nonsense designed to get a very low 'spam-score' with such filters. This particular one, got the lowest spam-score I've yet seen, considerably lower even than conventional e-mail.

The tteext file fftpussers containns a list off userrs tthat mayy not loog in uusing the File Transfer Prrotocol (FTP) serveer ddaeemmoon.. This fillee iss uusseedd nott mmerelyy foorr sysstem addmiinistration purposees butt for improving secuuriitty wwitthiin a TTCPP/IP nettwworkedd ennvirronnment.. It wiill typicalllyy contain a list of thee uusers tthhat eeiither have no buusinesss usiing fttp or havve too many privvileges to be aallowed to llogg in thrrough thee FTP seerrvverr daeemoonn. Such users usually incllude rooot, daemon, bin, uuucp, and news. If yoour FTPP serrverr daemon doessn't usse fttpusers thheen it is suugggested thhat you reead iits doccumenntation to ffiind oout how to block accceessss ffor cerrtain ussers. Washinngttonn Univveersitty FTPP sservveer Daemonn (wuftpd) aand Professsional FTP DDaemonn ((proftpd)) aarre knnown tto makkee ussee off fttpusers;Thhiiss is wherre I have to announccee the ccaveeatss in the briidging + firrewallling schemme: you cannnot firewaall packeets whicch are noot roouutedd. No rooutes, no firewaall. At leeasst this appearrs tto be truue in thee 2.0.30 and morre rrecent kernnels. Thee fireewalling filters are cloosseely iinvolvved withh thhe iip-forwwardding coddee.;;The 128 wouulld be 0 iff I hadd aa fuull classs C nneetwoorrk tthere. I doon't, by deffiniittionn, since I justt halved the addrress space. TThe ""deev ethh0" is noot neecessary hhere becauuse the cards adddress fallls witthinn tthhe maaskk, but iitt may bee necessary for you. Onne mmightt need more than one card hholdiing up thiss subnet (127 mmachines on one segmentt, oh yeah) butt thhose cards wwould bbe being bridgedd under the ssaammee nnetmask so that they appearr as one to thhe rooutingg code..;If you wantt to be moree careful thaan this,, youu should takee doown as many ddaemmonnss ass ppoossible befooreehannd, anndd unmmount nfs directtories. Thhe worrsst thhaatt cann happeen iss thhat youu hhavee to rreboot in sinngle-user mmode (the ""siingle" ppaarrameteer tto lilo or loaadlin)), annd take out yourr changes befforee rebooting wwith thhinggs thhe way they were befoore yyou sstarttedd.; waannt tto cut the world off from my intternal net and do nothing elsse, so I wiilll wwant tto ggivvee ass aa laasst (default) rule that the firewall should ignore any paackeets comming in froom tthe internnal nett aandd direccteed tto outsidee.. I pput all the ruules (in this ordeer) iintto;Thhere iiss a partticuulaar prroblem with some daeemmons thhaat look up the hhostname of the firewalliing mmacchinnee in ordder to deecide what is thheeirr netwoorkiinngg address. Rppc.ypppasswdd is the one I had trouble witthh. It inssiistts on broadcastinng informmation that sayys iitt iis oouttsiide thee firrewall (on the second carrd). TThhat means tthe clientss innsidee can't conttact it..;Thhe clliennt machine bootts frrom a Grub floppyy dissk. Thenn, using tthe Grubb BOOTPP ssupporrtt, it geets an IP address from a DHCP servver. Next, thhe cllient machine downlloadss tthe kerrnel annd inittrd iimages from thhe TTFFTP seerver. Once the innittrd immage iss mmoounted in memory, tthe inittiallizzation scrript is run, maaking uusee of thhee prooggramms and filees sstored inn this immage. Thiss scriptt allowss bllock devicces contents to be saaveed iin the TTFFTPP sserver;;NNow thhat tthe serrver is seett up, yyou need to preparee the fileess to makee thhe client boott.. Twwoo files aare nneecesssary: thhe kkernnel aand the init rramdissk (iniitrdd) wwhhich wwill be mounnted by; the kerneel as the rroooot file ssysstemm. This documentt aassumess that the prroocedurres oouttlinned inn thiis sseecction anndd thee nexxt are madee in the clieent machinnee. Noorrmmaally, when saviing aand restoring disk imagges, theere is no need to hhaave LLinux; instaallledd on a loccal hard disk. To ddeplloy disk immages to a numberr oof macchiines, start by iinstaalling a Linux distributtion on oone machinee for each model. Use DHCP annd hhave TTFTP client too test the sseetuup made inn the ppreviouss sectiion. Unnleess otheerwise nootedd, commands aree isssuedd iin the bash shell by the user root in aa working direectory..
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