fasten afsten fsaten sfaten asften saften fatsen aftsen ftasen tfasen atfsen tafsen fstaen sftaen ftsaen tfsaen stfaen tsfaen astfen satfen atsfen tasfen stafen tsafen fasetn afsetn fsaetn sfaetn asfetn safetn faestn afestn feastn efastn aefstn eafstn fseatn sfeatn fesatn efsatn sefatn esfatn aseftn saeftn aesftn easftn seaftn esaftn fatesn aftesn ftaesn tfaesn atfesn tafesn faetsn afetsn featsn efatsn aeftsn eaftsn fteasn tfeasn fetasn eftasn tefasn etfasn atefsn taefsn aetfsn eatfsn teafsn etafsn fstean sftean ftsean tfsean stfean tsfean fsetan sfetan festan efstan seftan esftan ftesan tfesan fetsan eftsan tefsan etfsan stefan tsefan setfan estfan tesfan etsfan astefn satefn atsefn tasefn staefn tsaefn asetfn saetfn aestfn eastfn seatfn esatfn atesfn taesfn aetsfn eatsfn teasfn etasfn steafn tseafn setafn estafn tesafn etsafn fastne afstne fsatne sfatne asftne saftne fatsne aftsne ftasne tfasne atfsne tafsne fstane sftane ftsane tfsane stfane tsfane astfne satfne atsfne tasfne stafne tsafne fasnte afsnte fsante sfante asfnte safnte fanste afnste fnaste nfaste anfste nafste fsnate sfnate fnsate nfsate snfate nsfate asnfte sanfte ansfte nasfte snafte nsafte fatnse aftnse ftanse tfanse atfnse tafnse fantse afntse fnatse nfatse anftse naftse ftnase tfnase fntase nftase tnfase ntfase atnfse tanfse antfse natfse tnafse ntafse fstnae sftnae ftsnae tfsnae stfnae tsfnae fsntae sfntae fnstae nfstae snftae nsftae ftnsae tfnsae fntsae nftsae tnfsae ntfsae stnfae tsnfae sntfae nstfae tnsfae ntsfae astnfe satnfe atsnfe tasnfe stanfe tsanfe asntfe santfe anstfe nastfe snatfe nsatfe atnsfe tansfe antsfe natsfe tnasfe ntasfe stnafe tsnafe sntafe nstafe tnsafe ntsafe fasent afsent fsaent sfaent asfent safent faesnt afesnt feasnt efasnt aefsnt eafsnt fseant sfeant fesant efsant sefant esfant asefnt saefnt aesfnt easfnt seafnt esafnt fasnet afsnet fsanet sfanet asfnet safnet fanset afnset fnaset nfaset anfset nafset fsnaet sfnaet fnsaet nfsaet snfaet nsfaet asnfet sanfet ansfet nasfet snafet nsafet faenst afenst feanst efanst aefnst eafnst fanest afnest fnaest nfaest anfest nafest fenast efnast fneast nfeast enfast nefast aenfst eanfst anefst naefst enafst neafst fsenat sfenat fesnat efsnat sefnat esfnat fsneat sfneat fnseat nfseat snfeat nsfeat fensat efnsat fnesat nfesat enfsat nefsat senfat esnfat snefat nsefat ensfat nesfat asenft saenft aesnft easnft seanft esanft asneft saneft anseft naseft snaeft nsaeft aensft eansft anesft naesft enasft neasft senaft esnaft sneaft nseaft ensaft nesaft fatens aftens ftaens tfaens atfens tafens faetns afetns featns efatns aeftns eaftns fteans tfeans fetans eftans tefans etfans atefns taefns aetfns eatfns teafns etafns fatnes aftnes ftanes tfanes atfnes tafnes fantes afntes fnates nfates anftes naftes ftnaes tfnaes fntaes nftaes tnfaes ntfaes atnfes tanfes antfes natfes tnafes ntafes faents afents feants efants aefnts eafnts fanets afnets fnaets nfaets anfets nafets fenats efnats fneats nfeats enfats nefats aenfts eanfts anefts naefts enafts neafts ftenas tfenas fetnas eftnas tefnas etfnas ftneas tfneas fnteas nfteas tnfeas ntfeas fentas efntas fnetas nfetas enftas neftas tenfas etnfas tnefas ntefas entfas netfas atenfs taenfs aetnfs eatnfs teanfs etanfs atnefs tanefs antefs natefs tnaefs ntaefs aentfs eantfs anetfs naetfs enatfs neatfs tenafs etnafs tneafs nteafs entafs netafs fstena sftena ftsena tfsena stfena tsfena fsetna sfetna festna efstna seftna esftna ftesna tfesna fetsna eftsna tefsna etfsna stefna tsefna setfna estfna tesfna etsfna fstnea sftnea ftsnea tfsnea stfnea tsfnea fsntea sfntea fnstea nfstea snftea nsftea ftnsea tfnsea fntsea nftsea tnfsea ntfsea stnfea tsnfea sntfea nstfea tnsfea ntsfea fsenta sfenta fesnta efsnta sefnta esfnta fsneta sfneta fnseta nfseta snfeta nsfeta fensta efnsta fnesta nfesta enfsta nefsta senfta esnfta snefta nsefta ensfta nesfta ftensa tfensa fetnsa eftnsa tefnsa etfnsa ftnesa tfnesa fntesa nftesa tnfesa ntfesa fentsa efntsa fnetsa nfetsa enftsa neftsa tenfsa etnfsa tnefsa ntefsa entfsa netfsa stenfa tsenfa setnfa estnfa tesnfa etsnfa stnefa tsnefa sntefa nstefa tnsefa ntsefa sentfa esntfa snetfa nsetfa enstfa nestfa tensfa etnsfa tnesfa ntesfa entsfa netsfa astenf satenf atsenf tasenf staenf tsaenf asetnf saetnf aestnf eastnf seatnf esatnf atesnf taesnf aetsnf eatsnf teasnf etasnf steanf tseanf setanf estanf tesanf etsanf astnef satnef atsnef tasnef stanef tsanef asntef santef anstef nastef snatef nsatef atnsef tansef antsef natsef tnasef ntasef stnaef tsnaef sntaef nstaef tnsaef ntsaef asentf saentf aesntf easntf seantf esantf asnetf sanetf ansetf nasetf snaetf nsaetf aenstf eanstf anestf naestf enastf neastf senatf esnatf sneatf nseatf ensatf nesatf atensf taensf aetnsf eatnsf teansf etansf atnesf tanesf antesf natesf tnaesf ntaesf aentsf eantsf anetsf naetsf enatsf neatsf tenasf etnasf tneasf nteasf entasf netasf stenaf tsenaf setnaf estnaf tesnaf etsnaf stneaf tsneaf snteaf nsteaf tnseaf ntseaf sentaf esntaf snetaf nsetaf enstaf nestaf tensaf etnsaf tnesaf ntesaf entsaf netsaf
Note: these 'words' (valid or invalid) are all the permutations of the word fasten. These words are obtained by scrambling the letters in fasten.