mobilon.ru<\/a><\/noindex> a ve spodn\u00ed \u010d\u00e1sti (v pati\u010dce str\u00e1nky) uvid\u00edte ip adresu va\u0161eho routeru.<\/p>\n<\/p>\n
Nap\u0159\u00edklad, j\u00e1 jsem se p\u0159ihl\u00e1sil z dom\u00e1c\u00edho internetu:<\/p>\n
<\/p>\n
<\/p>\n
Jak vid\u00edte, ve skute\u010dnosti m\u00e1m \u0161edou ip adresu 172.17.132.2<\/strong> (viz rozsah lok\u00e1ln\u00edch adres). Pro p\u0159ipojen\u00ed b\u00edl\u00e9 ip adresy poskytovatel\u00e9 obvykle poskytuj\u00ed dal\u0161\u00ed slu\u017ebu za poplatek.<\/p>\n<\/p>\n
Ve skute\u010dnosti pro dom\u00e1c\u00ed internet to nen\u00ed kritick\u00e9. Ale pro kancel\u00e1\u0159e firem se doporu\u010duje zakoupit od poskytovatele pr\u00e1v\u011b b\u00edlou ip adresu,<\/strong>proto\u017ee pou\u017e\u00edv\u00e1n\u00ed \u0161ed\u00e9 ip adresy p\u0159in\u00e1\u0161\u00ed probl\u00e9my s fungov\u00e1n\u00edm ip telefonie, stejn\u011b jako nebude mo\u017en\u00e9 nastavit vzd\u00e1len\u00e9 p\u0159ipojen\u00ed p\u0159es VPN. To znamen\u00e1, \u017ee \u0161ed\u00e1 ip adresa v\u00e1m neumo\u017en\u00ed vystavit na internet v\u00e1\u0161 nastaven\u00fd server a neumo\u017en\u00ed nastavit vzd\u00e1len\u00e9 p\u0159ipojen\u00ed na server z jin\u00e9 s\u00edt\u011b.<\/p>\n<\/p>\n
3. NAT<\/h3>\n <\/p>\n
V p\u0159edchoz\u00ed \u010d\u00e1sti jsem zm\u00ednil, \u017ee \"V sou\u010dasnosti se vyhrotil probl\u00e9m nedostatku ve\u0159ejn\u00fdch IP adres.<\/em>A proto je nyn\u00ed b\u011b\u017en\u00fdm sch\u00e9matem p\u0159ipojen\u00ed u poskytovatel\u016f internetu p\u0159ipojovat mnoho klient\u016f pomoc\u00ed soukrom\u00fdch IP adres a na glob\u00e1ln\u00ed internet je vypou\u0161t\u011bt pod jednou spole\u010dnou ve\u0159ejnou IP.<\/p>\n<\/p>\n
Ale tak tomu nebylo v\u017edy, na za\u010d\u00e1tku byly v\u0161em p\u0159id\u011blov\u00e1ny ve\u0159ejn\u00e9 IP adresy a brzy, aby se p\u0159ede\u0161lo probl\u00e9mu nedostatku ve\u0159ejn\u00fdch IP adres, byl pr\u00e1v\u011b vymy\u0161len NAT (p\u0159ekl\u00e1d\u00e1n\u00ed adres s\u00edt\u011b) \u2014 mechanismus p\u0159ekl\u00e1d\u00e1n\u00ed IP adres.<\/strong>.<\/p>\n<\/p>\n
NAT<\/strong> Funguje na v\u0161ech routerech a umo\u017e\u0148uje n\u00e1m vstupovat z lok\u00e1ln\u00ed s\u00edt\u011b do glob\u00e1ln\u00ed.<\/p>\n<\/p>\n
Pro lep\u0161\u00ed pochopen\u00ed si rozebr\u00e1me dva p\u0159\u00edklady:<\/p>\n
<\/p>\n
1. Prvn\u00ed p\u0159\u00edpad:<\/strong> m\u00e1te zakoupenou ve\u0159ejnou IP adresu 91.105.8.10<\/strong> a v lok\u00e1ln\u00ed s\u00edti je p\u0159ipojeno n\u011bkolik za\u0159\u00edzen\u00ed.<\/p>\n<\/p>\n
<\/p>\n
Ka\u017ed\u00e9 lok\u00e1ln\u00ed za\u0159\u00edzen\u00ed m\u00e1 svou soukromou IP adresu. Ale p\u0159\u00edstup na internet je mo\u017en\u00fd pouze s ve\u0159ejnou IP adresou.<\/p>\n
<\/p>\n
Proto, kdy\u017e nap\u0159\u00edklad PC1 s IP adresou 192.168.1.3 se rozhodne vstoupit do vyhled\u00e1va\u010de Yandex, router p\u0159i odes\u00edl\u00e1n\u00ed po\u017eadavku PC1 do glob\u00e1ln\u00ed s\u00edt\u011b zap\u00edn\u00e1 mechanismus NAT<\/strong>, kter\u00fd a p\u0159ev\u00e1d\u00ed IP adresu PC1 na ve\u0159ejnou glob\u00e1ln\u00ed IP adresu 91.105.8.10.<\/strong><\/p>\n<\/p>\n
Stejn\u011b tak i na zp\u00e1te\u010dn\u00ed cest\u011b, kdy\u017e router dostane odpov\u011b\u010f od serveru Yandex, pomoc\u00ed mechanismu NAT<\/strong> po\u0161le tuto odpov\u011b\u010f na IP adresu 192.168.1.3, na kterou je p\u0159ipojeno PC1.<\/p>\n<\/p>\n
2. Druh\u00fd p\u0159\u00edpad:<\/strong> ve va\u0161\u00ed lok\u00e1ln\u00ed s\u00edti je tak\u00e9 p\u0159ipojeno n\u011bkolik za\u0159\u00edzen\u00ed, ale ve\u0159ejnou IP adresu jste od poskytovatele internetu nekupovali.<\/p>\n<\/p>\n
<\/p>\n
V tomto p\u0159\u00edpad\u011b se lok\u00e1ln\u00ed adresa PC1 (192.168.1.3)<\/strong> nejd\u0159\u00edve p\u0159ev\u00e1d\u00ed NAT<\/strong>s va\u0161\u00edm routerem a m\u011bn\u00ed se na soukromou IP adresu 172.17.115.3<\/strong>, kterou v\u00e1m p\u0159id\u011blil poskytovatel internetu, a pot\u00e9 se va\u0161e soukrom\u00e1 IP adresa p\u0159ev\u00e1d\u00ed NAT<\/strong>routerem poskytovatele na ve\u0159ejnou IP adresu 91.105.108.10<\/strong>, a teprve pot\u00e9 doch\u00e1z\u00ed k p\u0159\u00edstupu na internet (glob\u00e1ln\u00ed s\u00ed\u0165).<\/p>\n<\/p>\n
To znamen\u00e1, \u017ee v tomto p\u0159\u00edpad\u011b se va\u0161e za\u0159\u00edzen\u00ed nach\u00e1zej\u00ed za dvojit\u00fdm NAT<\/strong>NAT.<\/p>\n<\/p>\n
Toto sch\u00e9ma m\u00e1 vy\u0161\u0161\u00ed \u00farove\u0148 bezpe\u010dnosti va\u0161ich za\u0159\u00edzen\u00ed, ale tak\u00e9 m\u00e1 \u0159adu v\u011bt\u0161\u00edch nev\u00fdhod. Nap\u0159\u00edklad nestabiln\u00ed SIP registrace VoIP za\u0159\u00edzen\u00ed nebo jednostrann\u00e1 sly\u0161itelnost p\u0159i vol\u00e1n\u00edch p\u0159es IP telefonii.<\/p>\n
<\/p>\n
Podrobn\u011bji o fungov\u00e1n\u00ed mechanismu NAT<\/strong>, o jeho v\u00fdhod\u00e1ch a nev\u00fdhod\u00e1ch, o p\u0159id\u011blov\u00e1n\u00ed port\u016f, o soketech a o typech NAT<\/strong> nap\u00ed\u0161u samostatn\u00fd \u010dl\u00e1nek.<\/p>\n<\/p>\n
4. DHCP \u2014 server a pods\u00edt\u011b.<\/h3>\n <\/p>\n
Abyste p\u0159ipojili za\u0159\u00edzen\u00ed, jako nap\u0159\u00edklad po\u010d\u00edta\u010d, k internetu, obvykle jednodu\u0161e zapoj\u00edte kabel (twisted pair) do po\u010d\u00edta\u010de a pak do voln\u00e9ho portu na routeru, po \u010dem\u017e po\u010d\u00edta\u010d automaticky obdr\u017e\u00ed IP adresu a dojde k p\u0159ipojen\u00ed k internetu. <\/p>\n
<\/p>\n
Podobn\u011b je to s Wi-Fi, nap\u0159\u00edklad se smartphonem nebo notebookem, p\u0159ipoj\u00edte se k po\u017eadovan\u00e9 s\u00edti, zad\u00e1te heslo, za\u0159\u00edzen\u00ed obdr\u017e\u00ed IP adresu a m\u00e1te internet.<\/p>\n
<\/p>\n
A co umo\u017e\u0148uje za\u0159\u00edzen\u00ed automaticky z\u00edskat lok\u00e1ln\u00ed IP adresu?<\/strong>DHCP server<\/strong>.<\/p>\n<\/p>\n
Ka\u017edi\u010dk\u00fd router je vybaven DHCP serverem.<\/strong>Automaticky z\u00edskan\u00e9 IP adresy jsou dynamick\u00e9 IP adresy.<\/strong>.<\/p>\n<\/p>\n
Pro\u010d dynamick\u00e9?<\/p>\n
<\/p>\n
Proto\u017ee p\u0159i ka\u017ed\u00e9m nov\u00e9m p\u0159ipojen\u00ed nebo restartu routeru DHCP server<\/strong> se tak\u00e9 restartuje a m\u016f\u017ee p\u0159id\u011blit za\u0159\u00edzen\u00ed r\u016fzn\u00fdm IP adres\u00e1m.<\/p>\n<\/p>\n
To znamen\u00e1, nap\u0159\u00edklad, te\u010f m\u00e1 v\u00e1\u0161 po\u010d\u00edta\u010d IP adresu 192.168.1.10<\/strong>, po restartu routeru m\u016f\u017ee IP adresa po\u010d\u00edta\u010de b\u00fdt 192.168.1.35<\/strong><\/p>\n<\/p>\n
Aby IP adresa z\u016fstala stejn\u00e1, m\u016f\u017ee b\u00fdt nastavena staticky.<\/strong>To lze prov\u00e9st jak na po\u010d\u00edta\u010di v nastaven\u00ed s\u00edt\u011b, tak p\u0159\u00edmo na routeru.<\/p>\n<\/p>\n
Tak\u00e9 je mo\u017en\u00e9 DHCP server<\/strong> na routeru zcela vypnout DHCP a IP adresy p\u0159id\u011blovat ru\u010dn\u011b.<\/p>\n<\/p>\n
Na jednom routeru je mo\u017en\u00e9 nastavit n\u011bkolik DHCP server\u016f.<\/strong> Pak se m\u00edstn\u00ed s\u00ed\u0165 rozd\u011bl\u00ed na pods\u00ed\u0165.<\/strong>. <\/p>\n<\/p>\n
Nap\u0159\u00edklad p\u0159ipoj\u00edme po\u010d\u00edta\u010de k nult\u00e9 pods\u00edti v rozsahu 192.168.0.2-192.168.0.255, tisk\u00e1rny k prvn\u00ed pods\u00edti v rozsahu 192.168.1.2-192.168.1.255 a Wi-Fi budeme sd\u00edlet na p\u00e1t\u00e9 pods\u00edti s rozsahem 192.168.5.2-192.168.5.255 (viz sch\u00e9ma n\u00ed\u017ee).<\/p>\n
<\/p>\n
<\/p>\n
Obvykle nen\u00ed pot\u0159eba d\u011blit pods\u00edt\u011b. To se d\u011bl\u00e1, kdy\u017e m\u00e1 spole\u010dnost velk\u00e9 mno\u017estv\u00ed za\u0159\u00edzen\u00ed p\u0159ipojen\u00fdch k s\u00edti a p\u0159i nastavov\u00e1n\u00ed s\u00ed\u0165ov\u00e9 bezpe\u010dnosti.<\/p>\n
<\/p>\n
Ale takov\u00e9 sch\u00e9ma se v firm\u00e1ch \u010dasto vyskytuje.
<\/p>\n
Pozor!<\/p>\n
Pro pochopen\u00ed se pod\u00edv\u00e1me na p\u0159\u00edklad:<\/p>\n
<\/p>\n
<\/p>\n
P\u0159edstavte si, \u017ee pracujete na PC1<\/strong> s lok\u00e1ln\u00ed IP adresou 10.10.5.2<\/strong> a chcete p\u0159istupovat na webov\u00e9 rozhran\u00ed IP telefonu,<\/strong> s lok\u00e1ln\u00ed IP adresou 192.168.1.3<\/strong>tak se nep\u0159ipoj\u00edte. Proto\u017ee za\u0159\u00edzen\u00ed jsou v r\u016fzn\u00fdch pods\u00edt\u00edch. Na IP telefon nach\u00e1zej\u00edc\u00ed se v pods\u00edti 192.168.1.X<\/strong>, se lze p\u0159ipojit pouze z PC3 (192.168.1.5).<\/strong>.<\/p>\n<\/p>\n
Stejn\u011b tak k MFP (172.17.17.12)<\/strong> se budete moci p\u0159ipojit pouze z PC4 (172.17.17.10)<\/strong>.<\/p>\n<\/p>\n
Proto, kdy\u017e se p\u0159ipojujete vzd\u00e1len\u011b k u\u017eivateli na PC, abyste se dostali na webov\u00e9 rozhran\u00ed IP telefonu, v\u017edy nejd\u0159\u00edve zkontrolujte jejich lok\u00e1ln\u00ed IP adresy, abyste se ujistili, \u017ee jsou ob\u011b za\u0159\u00edzen\u00ed p\u0159ipojena k jedn\u00e9 pods\u00edti.<\/p>\n
<\/p>\n
5. Za\u0159\u00edzen\u00ed pro sm\u011brov\u00e1n\u00ed s\u00edt\u011b (sm\u011brova\u010d, p\u0159ep\u00edna\u010d, switch, hub)<\/h3>\n <\/p>\n
Jak podivn\u00e9, ale je to fakt, \u017ee za\u010d\u00e1te\u010dn\u00edci v IT (n\u011bkdy i ji\u017e zku\u0161en\u00e9 syst\u00e9mov\u00e9 administr\u00e1tory) nev\u011bd\u00ed nebo si pletou takov\u00e9 pojmy jako sm\u011brova\u010d, p\u0159ep\u00edna\u010d, switch, s\u00ed\u0165ov\u00e1 br\u00e1na a hub<\/strong>.<\/p>\n<\/p>\n
Mysl\u00edm, \u017ee d\u016fvodem t\u00e9to z\u00e1m\u011bny je to, \u017ee se v n\u00e1zvech s\u00ed\u0165ov\u00fdch za\u0159\u00edzen\u00ed vyskytuje mnoho synonym a \u017eargon\u016f, a to nyn\u00ed uv\u00e1d\u00ed do zmatku mnoh\u00e9 za\u010d\u00ednaj\u00edc\u00ed in\u017een\u00fdry.<\/p>\n
<\/p>\n
Poj\u010fme se na to pod\u00edvat.<\/p>\n
<\/p>\n
a) Router, sm\u011brova\u010d a s\u00ed\u0165ov\u00e1 br\u00e1na<\/strong><\/p>\n<\/p>\n
V\u0161ichni v\u011bd\u00ed, co je to router<\/strong>. Je to za\u0159\u00edzen\u00ed, kter\u00e9 sd\u00edl\u00ed internet v m\u00edstnosti, p\u0159ipojen\u00fd od poskytovatele internetu.<\/p>\n<\/p>\n
Tak tedy sm\u011brova\u010d a s\u00ed\u0165ov\u00e1 br\u00e1na jsou vlastn\u011b router<\/strong>.<\/p>\n<\/p>\n
Toto za\u0159\u00edzen\u00ed je hlavn\u00ed v organizaci s\u00edt\u011b. V in\u017een\u00fdrsk\u00e9 sf\u00e9\u0159e je nejv\u00edce pou\u017e\u00edvan\u00e9 ozna\u010den\u00ed \u201csm\u011brova\u010d<\/strong>\u201d.<\/p>\n<\/p>\n
Mimochodem, routerem nemus\u00ed b\u00fdt jen set-top box, ale tak\u00e9 syst\u00e9mov\u00e1 jednotka po\u010d\u00edta\u010de, pokud do n\u00ed nainstalujete dal\u0161\u00ed s\u00ed\u0165ovou kartu a nap\u0159\u00edklad RouterOS Mikrotik. Pot\u00e9 rozvetvte s\u00ed\u0165 na mnoho za\u0159\u00edzen\u00ed pomoc\u00ed switche.<\/p>\n
<\/p>\n
<\/p>\n
b) Co je to Switch a jak se li\u0161\u00ed od P\u0159ep\u00edna\u010de a Hubu<\/strong><\/p>\n<\/p>\n
Switch a P\u0159ep\u00edna\u010d<\/strong> jsou tak\u00e9 synonymy<\/strong>. A nyn\u00ed hub<\/strong> je trochu jin\u00e9 za\u0159\u00edzen\u00ed. O n\u011bm se dozv\u00edte v dal\u0161\u00edm bod\u011b (v).<\/p>\n<\/p>\n
<\/p>\n
P\u0159ep\u00edna\u010d (switch)<\/strong> slou\u017e\u00ed k rozv\u011btven\u00ed lok\u00e1ln\u00ed s\u00edt\u011b. Jako troj\u00edtko nebo s\u00ed\u0165ov\u00e1 prodlu\u017eova\u010dka, kam p\u0159ipojujeme sv\u00e1 za\u0159\u00edzen\u00ed, abychom je nap\u00e1jeli elektrick\u00fdm proudem z jedn\u00e9 z\u00e1suvky.<\/p>\n<\/p>\n
<\/p>\n
P\u0159ep\u00edna\u010d neum\u00ed sm\u011brovat s\u00ed\u0165 jako router<\/strong>. Nep\u0159id\u011bl\u00ed va\u0161\u00ed mu za\u0159\u00edzen\u00ed IP adresu a bez pomoci routeru v\u00e1s nem\u016f\u017ee vydat na internet.<\/p>\n<\/p>\n
Standardn\u00ed sm\u011brova\u010d obvykle m\u00e1 4-5 port\u016f pro p\u0159ipojen\u00ed za\u0159\u00edzen\u00ed. Pokud jsou va\u0161e za\u0159\u00edzen\u00ed p\u0159ipojena kabelem a je jich v\u00edce ne\u017e port\u016f na routeru, budete pot\u0159ebovat switch. K jednomu portu routeru m\u016f\u017eete p\u0159ipojit switch na 24 port\u016f a v klidu zorganizovat lok\u00e1ln\u00ed s\u00ed\u0165 na 24 za\u0159\u00edzen\u00ed.<\/p>\n
<\/p>\n
A pokud m\u00e1te je\u0161t\u011b jeden router, m\u016f\u017eete v jeho webov\u00e9m rozhran\u00ed zapnout re\u017eim p\u0159ep\u00edna\u010de a tak\u00e9 ho pou\u017e\u00edt jako switch.<\/p>\n
<\/p>\n
v) Hub<\/strong><\/p>\n<\/p>\n
Hub<\/strong> m\u00e1 stejnou funkci jako switch. Ale jeho technologie rozd\u011blov\u00e1n\u00ed je zna\u010dn\u011b zastaral\u00e1.<\/p>\n<\/p>\n
<\/p>\n
Hub<\/strong> distribuuje p\u0159\u00edchoz\u00ed pakety od routeru v\u0161em p\u0159ipojen\u00fdm za\u0159\u00edzen\u00edm bez rozli\u0161ov\u00e1n\u00ed, a za\u0159\u00edzen\u00ed si ji\u017e sama mus\u00ed zjistit, zda se jedn\u00e1 o jejich paket nebo ne.<\/p>\n<\/p>\n
A switch m\u00e1 tabulku MAC adres<\/strong> a proto rozd\u011bluje p\u0159\u00edchoz\u00ed pakety na jedno konkr\u00e9tn\u00ed za\u0159\u00edzen\u00ed, kter\u00e9 tento paket po\u017eadovalo. V d\u016fsledku toho p\u0159enos dat<\/strong> pomoc\u00ed switche je rychlej\u0161\u00ed a efektivn\u011bj\u0161\u00ed.<\/strong>.<\/p>\n<\/p>\n
V sou\u010dasn\u00e9 dob\u011b se ji\u017e vz\u00e1cn\u011b setk\u00e1v\u00e1me s pou\u017eit\u00edm hubu<\/strong>, ale p\u0159esto se ob\u010das vyskytuj\u00ed, je dobr\u00e9 na to b\u00fdt p\u0159ipraven a ur\u010dit\u011b doporu\u010dit u\u017eivateli v\u00fdm\u011bnu hubu za switch.<\/p>\n<\/p>\n
6. Hlavn\u00ed p\u0159\u00edkazy pro anal\u00fdzu s\u00edt\u011b<\/h3>\n <\/p>\n
a) P\u0159\u00edkaz Ping<\/strong><\/p>\n<\/p>\n
Pro pochopen\u00ed, zda je IP adresa nebo samotn\u00e9 za\u0159\u00edzen\u00ed aktivn\u00ed, m\u016f\u017eeme jej \u201epropingovat\u201c.ip-adresa<\/strong>\u201d.<\/p>\n<\/p>\n
<\/p>\n
Zde jsme \u201epingli\u201c DNS server Google a, jak vid\u00edme, server je aktivn\u00ed (odpis na pings je 83 ms).<\/p>\n
<\/p>\n
Pokud je adres\u00e1t nedostupn\u00fd nebo dan\u00e1 IP adresa neexistuje, uvid\u00edme tuto situaci:<\/p>\n
<\/p>\n
<\/p>\n
To znamen\u00e1, \u017ee na pings nedost\u00e1v\u00e1me odpov\u011b\u010f.<\/p>\n
<\/p>\n
Ale Ping<\/strong> mnohem u\u017eite\u010dn\u011bj\u0161\u00ed je pou\u017e\u00edt s kl\u00ed\u010di:-t<\/strong> - \u201epingovat\u201c nep\u0159etr\u017eit\u011b (k zastaven\u00ed stiskneme kombinaci Ctrl+C)-a<\/strong> - zobrazit jm\u00e9no \u201epingovan\u00e9ho\u201c uzlu (webu\/za\u0159\u00edzen\u00ed\/serveru)<\/p>\n<\/p>\n
<\/p>\n
Odpov\u00eddaj\u00edc\u00ed kl\u00ed\u010d \"-a<\/strong>\" n\u00e1m uk\u00e1zal, \u017ee jm\u00e9no pingovan\u00e9ho uzlu je \"dns.google\".-t<\/strong>\" ping \u0161el bez zastaven\u00ed, zastavil jsem ho stisknut\u00edm Ctrl+C.<\/p>\n<\/p>\n
P\u0159i nep\u0159etr\u017eit\u00e9m pingu lze vid\u011bt, jak se pingovan\u00fd uzel chov\u00e1 a p\u0159ibli\u017enou kvalitu internetov\u00e9ho p\u0159ipojen\u00ed.<\/p>\n
<\/p>\n
Jak vid\u00edme ze screenshotu, ob\u010das doch\u00e1z\u00ed ke zpo\u017ed\u011bn\u00ed p\u0159\u00edjmu paketu a\u017e 418 ms, co\u017e je pom\u011brn\u011b kritick\u00e1 hodnota, proto\u017ee skok z 83 ms na 418 ms by se projevil na videohovoru jako trh\u00e1n\u00ed\/zasek\u00e1v\u00e1n\u00ed obrazu nebo v IP telefonii jako degradace kvality hlasu.<\/p>\n
<\/p>\n
V m\u00e9m p\u0159\u00edpad\u011b pravd\u011bpodobn\u011b m\u011bl probl\u00e9m s m\u00fdm dom\u00e1c\u00edm internetem.
<\/p>\n
Pozor!<\/strong> N\u011bkdy na routerech je zak\u00e1z\u00e1no odes\u00edl\u00e1n\u00ed ICMP<\/strong> paket\u016f (n\u011bkdo je vyp\u00edn\u00e1 z\u00e1m\u011brn\u011b, jinde nejsou ve v\u00fdchoz\u00edm nastaven\u00ed zapnuty), v takov\u00e9m p\u0159\u00edpad\u011b na \"pinky\" takov\u00fd uzel nebude odpov\u00eddat, i kdy\u017e s\u00e1m bude aktivn\u00ed a norm\u00e1ln\u011b funguje v s\u00edti.<\/p>\n<\/p>\n
Dal\u0161\u00ed mo\u017enost\u00ed \u201cpingu\u201d je Zjistit, jak\u00e1 IP adresa se skr\u00fdv\u00e1 za dom\u00e9nou webu<\/strong>. A konkr\u00e9tn\u011b, na jak\u00e9m serveru je webov\u00e1 hostovan\u00e1.<\/p>\n<\/p>\n
K tomu jednodu\u0161e m\u00edsto IP adresy nap\u00ed\u0161eme web:<\/p>\n
<\/p>\n
<\/p>\n
Jak vid\u00edte, IP adresa pro Habra je 178.248.237.68<\/strong><\/p>\n<\/p>\n
b) Tracov\u00e1n\u00ed<\/strong><\/p>\n<\/p>\n
N\u011bkdy je velmi d\u016fle\u017eit\u00e9 vid\u011bt, jakou cestou putuje paket k ur\u010dit\u00e9mu za\u0159\u00edzen\u00ed.n\u00e1stroj pro tracov\u00e1n\u00ed pom\u00e1h\u00e1 ur\u010dit, na jak\u00e9m kroku se paket zasek\u00e1v\u00e1<\/strong>.<\/p>\n<\/p>\n
V syst\u00e9mu Windows se tento n\u00e1stroj spou\u0161t\u00ed p\u0159\u00edkazem \u201ctracert\u201d IP adresa<\/strong> nebo dom\u00e9na:<\/p>\n<\/p>\n
<\/p>\n
Zde jsme vid\u011bli, p\u0159es jak\u00e9 uzly n\u00e1\u0161 po\u017eadavek proch\u00e1z\u00ed, ne\u017e doraz\u00ed k serveru ya.ru<\/p>\n
<\/p>\n
Na OS Linux<\/strong> tento n\u00e1stroj se spou\u0161t\u00ed p\u0159\u00edkazem traceroute<\/strong>.<\/p>\n<\/p>\n
N\u011bkter\u00e9 za\u0159\u00edzen\u00ed, sm\u011brova\u010de nebo hlasov\u00e9 VoIP br\u00e1ny tak\u00e9 disponuj\u00ed n\u00e1strojem pro tracov\u00e1n\u00ed.<\/p>\n
<\/p>\n
c) N\u00e1stroj whois<\/strong><\/p>\n<\/p>\n
Tento n\u00e1stroj umo\u017e\u0148uje zjistit v\u0161echny informace o IP adrese nebo o registr\u00e1torovi dom\u00e9ny<\/strong>.<\/p>\n<\/p>\n
Nap\u0159\u00edklad ov\u011b\u0159\u00edme IP adresu 145.255.1.71<\/strong>. K tomu zav\u00e1d\u00edm v termin\u00e1lu p\u0159\u00edkaz whois 145.255.1.71<\/strong><\/p>\n<\/p>\n
<\/p>\n
Dostali jsme informace o poskytovateli IP adresy, zemi, m\u011bst\u011b, adrese, rozsahu atd.<\/p>\n
<\/p>\n
Pou\u017e\u00edv\u00e1m ho jen na Linuxu. N\u00e1stroj se snadno stahuje a instaluje z standardn\u00edho repozit\u00e1\u0159e opera\u010dn\u00edho syst\u00e9mu.<\/p>\n
<\/p>\n
Ale tak\u00e9 jsem sly\u0161el, \u017ee podobn\u00e9 \u0159e\u0161en\u00ed je i na Windows.<\/p>\n
<\/p>\n
7. Transportn\u00ed protokoly TCP a UDP<\/h3>\n <\/p>\n
Ve\u0161ker\u00e9 p\u0159enosy po\u017eadavk\u016f a p\u0159\u00edjem odpov\u011bd\u00ed mezi za\u0159\u00edzen\u00edmi v s\u00edti prob\u00edhaj\u00ed pomoc\u00ed transportn\u00edch protokol\u016f TCP a UDP<\/strong>.<\/p>\n<\/p>\n
Protokol TCP zaji\u0161\u0165uje doru\u010den\u00ed po\u017eadavku a celistvost jeho p\u0159enosu.<\/strong> Ne\u017e ode\u0161le paket, p\u0159edem kontroluje dostupnost uzlu. A pokud b\u011bhem cesty dojde k poru\u0161en\u00ed celistvosti paketu, pak TCP<\/strong> dopl\u0148uje chyb\u011bj\u00edc\u00ed \u010d\u00e1sti.<\/p>\n<\/p>\n
Obecn\u011b je to protokol, kter\u00fd ud\u011bl\u00e1 v\u0161e pro to, aby v\u00e1\u0161 po\u017eadavek spr\u00e1vn\u011b dorazil k adres\u00e1tovi.<\/p>\n
<\/p>\n
Proto TCP<\/strong> nejroz\u0161\u00ed\u0159en\u011bj\u0161\u00ed transportn\u00ed protokol. Pou\u017e\u00edv\u00e1 se, kdy\u017e u\u017eivatel surfuje po internetu, nav\u0161t\u011bvuje weby, slu\u017eby, soci\u00e1ln\u00ed s\u00edt\u011b atd.<\/p>\n<\/p>\n
<\/p>\n
UDP<\/strong> protokol nem\u00e1 tak zaru\u010den\u00fd p\u0159enos dat jako TCP<\/strong>. Nezkontroluje dostupnost koncov\u00e9ho uzlu p\u0159ed odesl\u00e1n\u00edm a nedopl\u0148uje paket v p\u0159\u00edpad\u011b jeho degradace. Pokud se n\u011bjak\u00fd paket nebo n\u011bkolik paket\u016f po cest\u011b ztrat\u00ed, zpr\u00e1va doraz\u00ed k adres\u00e1tovi v takov\u00e9m ne\u00fapln\u00e9m stavu.<\/p>\n<\/p>\n
Pro\u010d je tedy UDP pot\u0159eba?<\/strong><\/p>\n<\/p>\n
Je to proto, \u017ee tento transportn\u00ed protokol m\u00e1 obrovskou v\u00fdhodu oproti TCP<\/strong> v rychlosti p\u0159enosu dat. Proto je UDP \u0161iroce pou\u017e\u00edv\u00e1n pro p\u0159enos hlasov\u00fdch a video paket\u016f v re\u00e1ln\u00e9m \u010dase<\/strong>. A to konkr\u00e9tn\u011b v IP telefonii a video hovorech.UDP<\/strong>. Stejn\u011b tak i p\u0159i video hovorech, nap\u0159\u00edklad p\u0159es Skype nebo zm\u00edn\u011bn\u00e9 messengery WhatsApp a Viber.<\/p>\n<\/p>\n
<\/p>\n
Pr\u00e1v\u011b proto, \u017ee UDP nezaru\u010duje absolutn\u00ed p\u0159enos dat a integritu p\u0159en\u00e1\u0161en\u00e9ho paketu, \u010dasto doch\u00e1z\u00ed k probl\u00e9m\u016fm p\u0159i hovorech p\u0159es internet.
<\/p>\n
Tento probl\u00e9m vznik\u00e1 kv\u016fli p\u0159et\u00ed\u017een\u00e9mu internetov\u00e9mu kan\u00e1lu, dvojit\u00e9mu NATu nebo r\u00e1diov\u00e9mu kan\u00e1lu.<\/p>\n
<\/p>\n
Bylo by jist\u011b dobr\u00e9 v t\u011bchto p\u0159\u00edpadech pou\u017e\u00edt TCP<\/strong>, ale bohu\u017eel, pro p\u0159enos hlasu je nutn\u00fd okam\u017eit\u00fd p\u0159enos celistv\u00fdch paket\u016f, a pro tuto \u00falohu je ide\u00e1ln\u00ed UDP<\/strong>. <\/p>\n<\/p>\n
Aby se p\u0159i pou\u017e\u00edv\u00e1n\u00ed UDP<\/strong> protokolu nevyskytly probl\u00e9my, je t\u0159eba jednodu\u0161e zorganizovat kvalitn\u00ed internetov\u00fd kan\u00e1l. A tak\u00e9 nastavit na routeru vyhrazenou \u0161\u00ed\u0159ku p\u00e1sma pro UDP<\/strong>, aby z\u00e1t\u011b\u017e z ostatn\u00edch za\u0159\u00edzen\u00ed, kter\u00e9 pou\u017e\u00edvaj\u00ed TCP<\/strong> nebr\u00e1nila pr\u00e1ci p\u0159enosov\u00e9ho protokolu. UDP<\/strong>.<\/p>\n<\/p>\n
To je v\u0161e.<\/strong><\/p>\n<\/p>\n
Nep\u0159et\u00ed\u017eil jsem \u010dl\u00e1nek a nekop\u00edroval jsem sem v\u011bdeck\u00e9 definice v\u0161ech pou\u017eit\u00fdch term\u00edn\u016f, kdo to pot\u0159ebuje, sta\u010d\u00ed vyhledat.<\/p>\n
<\/p>\n
Sna\u017eil jsem se shrom\u00e1\u017edit dohromady 7 nejd\u016fle\u017eit\u011bj\u0161\u00edch, podle m\u00e9ho n\u00e1zoru, bod\u016f, jejich\u017e znalost pom\u016f\u017ee mlad\u00e9mu \"aj\u0165\u00e1kovi\" proj\u00edt prvn\u00edmi f\u00e1zemi pohovoru na \"aj\u0165\u00e1ck\u00e9\" pozice nebo aspo\u0148 d\u00e1t najevo zam\u011bstnavateli, \u017ee v\u00edte v\u00edce ne\u017e b\u011b\u017en\u00fd u\u017eivatel.<\/p>\n
<\/p>\n
Studujte, d\u011blejte si pozn\u00e1mky. Douf\u00e1m, \u017ee \u010dl\u00e1nek mnoh\u00fdm p\u0159inese u\u017eitek.<\/p>\n
Zdroj: habr.com<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"\u041f\u0440\u0438\u043c\u0435\u0440\u043d\u043e 80% \u0438\u0437 \u043d\u0430\u0441, \u043a\u0442\u043e \u0437\u0430\u043a\u0430\u043d\u0447\u0438\u0432\u0430\u0435\u0442 \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442 \u0441 \u043a\u0430\u043a\u043e\u0439-\u043b\u0438\u0431\u043e IT-\u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e\u0441\u0442\u044c\u044e, \u0432 \u0438\u0442\u043e\u0433\u0435 \u043d\u0435 \u0441\u0442\u0430\u043d\u043e\u0432\u0438\u0442\u0441\u044f \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0441\u0442\u043e\u043c. \u041c\u043d\u043e\u0433\u0438\u0435 \u0443\u0441\u0442\u0440\u0430\u0438\u0432\u0430\u044e\u0442\u0441\u044f \u0432 \u0442\u0435\u0445\u043d\u0438\u0447\u0435\u0441\u043a\u0443\u044e \u043f\u043e\u0434\u0434\u0435\u0440\u0436\u043a\u0443, \u0441\u0438\u0441\u0442\u0435\u043c\u043d\u044b\u043c\u0438 \u0430\u0434\u043c\u0438\u043d\u0438\u0441\u0442\u0440\u0430\u0442\u043e\u0440\u0430\u043c\u0438, \u043c\u0430\u0441\u0442\u0435\u0440\u0430\u043c\u0438 \u043f\u043e \u043d\u0430\u043b\u0430\u0434\u043a\u0435 \u043a\u043e\u043c\u043f\u044c\u044e\u0442\u0435\u0440\u043d\u044b\u0445 \u0443\u0441\u0442\u0440\u043e\u0439\u0441\u0442\u0432, \u043a\u043e\u043d\u0441\u0443\u043b\u044c\u0442\u0430\u043d\u0442\u0430\u043c\u0438-\u043f\u0440\u043e\u0434\u0430\u0432\u0446\u0430\u043c\u0438 \u0446\u0438\u0444\u0440\u043e\u0432\u043e\u0439 \u0442\u0435\u0445\u043d\u0438\u043a\u0438, \u043c\u0435\u043d\u0435\u0434\u0436\u0435\u0440\u0430\u043c\u0438 \u0432 it-\u0441\u0444\u0435\u0440\u0443 \u0438 \u0442\u0430\u043a \u0434\u0430\u043b\u0435\u0435. \u042d\u0442\u0430 \u0441\u0442\u0430\u0442\u044c\u044f \u043a\u0430\u043a \u0440\u0430\u0437 \u0434\u043b\u044f \u0442\u0430\u043a\u0438\u0445 80%, \u043a\u0442\u043e \u0442\u043e\u043b\u044c\u043a\u043e \u0437\u0430\u043a\u043e\u043d\u0447\u0438\u043b \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442 \u0441 \u043a\u0430\u043a\u043e\u0439-\u043b\u0438\u0431\u043e IT-\u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e\u0441\u0442\u044c\u044e \u0438 \u0443\u0436\u0435 \u043d\u0430\u0447\u0430\u043b \u043c\u043e\u043d\u0438\u0442\u043e\u0440\u0438\u0442\u044c \u0432\u0430\u043a\u0430\u043d\u0441\u0438\u0438, […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":73868,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-73867","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t