{"id":8035,"date":"2026-05-13T11:01:29","date_gmt":"2026-05-13T10:01:29","guid":{"rendered":"https:\/\/workboot.fr\/ciela\/?page_id=8035"},"modified":"2026-05-13T15:16:36","modified_gmt":"2026-05-13T14:16:36","slug":"tcpdump","status":"publish","type":"page","link":"https:\/\/workboot.fr\/ciela\/tcpdump\/","title":{"rendered":"TCPDUMP"},"content":{"rendered":"\n

installer apache2<\/p>\n\n\n\n

sudo apt update\nsudo apt install apache2<\/code><\/pre>\n\n\n\n
dans \/var\/www\/html\/index.html<\/p>\n\n\n\n
Page minimale <\/p>\n\n\n\n
<!DOCTYPE html>\n<html>\n<head>\n    <title>Hello World<\/title>\n<\/head>\n<body>\n    <h1>Bonjour le monde !<\/h1>\n<\/body>\n<\/html>\n<\/code><\/pre>\n\n\n\n
Pour y acc\u00e9der, il faut contourner le proxy si il y un proxy  <\/p>\n\n\n\n
Navigateur chromium, firefox, chrome , curl , nous allons utiliser ce dernier<\/p>\n\n\n\n
curl --noproxy \"127.0.0.1\" 127.0.0.1<\/code><\/pre>\n\n\n\n
on obtient quelque chose comme cela :<\/p>\n\n\n\n
bruno@elliott:~\/Works\/tcpdump$ curl --noproxy \"127.0.0.1\" 127.0.0.1\n<!DOCTYPE html>\n<html>\n<head>\n    <title>Hello World<\/title>\n<\/head>\n<body>\n    <h1>Bonjour le monde !<\/h1>\n<\/body>\n<\/html>\nbruno@elliott:~\/Works\/tcpdump$ <\/code><\/pre>\n\n\n\n
Dans un autre terminal on va espionner la communication<\/p>\n\n\n\n
sudo tcpdump -i lo -A port 80<\/code><\/pre>\n\n\n\n
on voit ainsi les trames tcp entre le client et le serveur<\/p>\n\n\n\n
bruno@elliott:~\/Works\/tcpdump$ sudo tcpdump -i lo -A port 80\ntcpdump: verbose output suppressed, use -v[v]... for full protocol decode\nlistening on lo, link-type EN10MB (Ethernet), snapshot length 262144 bytes\n12:22:50.086400 IP localhost.47884 > localhost.http: Flags [S], seq 1113395499, win 65495, options [mss 65495,sackOK,TS val 2273228112 ecr 0,nop,wscale 7], length 0\nE..<.\\@.@..^...........PB].+.........0.........\n.~.P........\n12:22:50.086424 IP localhost.http > localhost.47884: Flags [S.], seq 1637539294, ack 1113395500, win 65483, options [mss 65495,sackOK,TS val 2273228112 ecr 2273228112,nop,wscale 7], length 0\nE..<..@.@.<..........P..a...B].,.....0.........\n.~.P.~.P....\n12:22:50.086445 IP localhost.47884 > localhost.http: Flags [.], ack 1, win 512, options [nop,nop,TS val 2273228112 ecr 2273228112], length 0\nE..4.]@.@..e...........PB].,a........(.....\n.~.P.~.P\n12:22:50.086533 IP localhost.47884 > localhost.http: Flags [P.], seq 1:74, ack 1, win 512, options [nop,nop,TS val 2273228112 ecr 2273228112], length 73: HTTP: GET \/ HTTP\/1.1\nE..}.^@.@..............PB].,a........q.....\n.~.P.~.PGET \/ HTTP\/1.1\nHost: 127.0.0.1\nUser-Agent: curl\/7.88.1\nAccept: *\/*\n\n\n12:22:50.086556 IP localhost.http > localhost.47884: Flags [.], ack 74, win 512, options [nop,nop,TS val 2273228112 ecr 2273228112], length 0\nE..4T,@.@............P..a...B].u.....(.....\n.~.P.~.P\n12:22:50.086832 IP localhost.http > localhost.47884: Flags [P.], seq 1:376, ack 74, win 512, options [nop,nop,TS val 2273228112 ecr 2273228112], length 375: HTTP: HTTP\/1.1 200 OK\nE...T-@.@............P..a...B].u...........\n.~.P.~.PHTTP\/1.1 200 OK\nDate: Wed, 13 May 2026 10:22:50 GMT\nServer: Apache\/2.4.67 (Debian)\nLast-Modified: Wed, 13 May 2026 09:22:58 GMT\nETag: \"7c-651af8688df34\"\nAccept-Ranges: bytes\nContent-Length: 124\nVary: Accept-Encoding\nContent-Type: text\/html\n\n<!DOCTYPE html>\n<html>\n<head>\n    <title>Hello World<\/title>\n<\/head>\n<body>\n    <h1>Bonjour le monde !<\/h1>\n<\/body>\n<\/html>\n\n12:22:50.086846 IP localhost.47884 > localhost.http: Flags [.], ack 376, win 510, options [nop,nop,TS val 2273228112 ecr 2273228112], length 0\nE..4._@.@..c...........PB].ua..V.....(.....\n.~.P.~.P\n12:22:50.087099 IP localhost.47884 > localhost.http: Flags [F.], seq 74, ack 376, win 512, options [nop,nop,TS val 2273228113 ecr 2273228112], length 0\nE..4.`@.@..b...........PB].ua..V.....(.....\n.~.Q.~.P\n12:22:50.087186 IP localhost.http > localhost.47884: Flags [F.], seq 376, ack 75, win 512, options [nop,nop,TS val 2273228113 ecr 2273228113], length 0\nE..4T.@.@............P..a..VB].v.....(.....\n.~.Q.~.Q\n12:22:50.087207 IP localhost.47884 > localhost.http: Flags [.], ack 377, win 512, options [nop,nop,TS val 2273228113 ecr 2273228113], length 0\nE..4.a@.@..a...........PB].va..W.....(.....\n.~.Q.~.Q\n^C\n10 packets captured\n20 packets received by filter\n0 packets dropped by kernel\nbruno@elliott:~\/Works\/tcpdump$ \n<\/code><\/pre>\n\n\n\n
c’est un dialogue entre le client et le serveur ( curl et apache)<\/p>\n\n\n\n
\ud83c\udfad SC\u00c8NE : localhost (votre PC joue les deux r\u00f4les)\n\n\ud83d\udcde CLIENT (curl)                    \ud83d\udda5\ufe0f SERVEUR (Apache)\n   port 47884                           port 80\n\n12:22:50.086400\n   [SYN] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba  \n   \"H\u00e9, je veux ouvrir une connexion\"\n\n12:22:50.086424\n   \u25c4\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 [SYN-ACK]\n   \"D'accord, je suis pr\u00eat \u00e0 te parler\"\n\n12:22:50.086445\n   [ACK] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba\n   \"Re\u00e7u, la ligne est ouverte\"\n\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n\ud83d\udcac LA CONVERSATION (\u00e9change de donn\u00e9es)\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n\n12:22:50.086533\n   [PUSH] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba\n   \"Voici ma question :\"\n   \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n   \u2502 GET \/ HTTP\/1.1                  \u2502\n   \u2502 Host: 127.0.0.1                 \u2502\n   \u2502 User-Agent: curl\/7.88.1         \u2502\n   \u2502 Accept: *\/*                     \u2502\n   \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n\n12:22:50.086556\n   \u25c4\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 [ACK]\n   \"J'ai bien re\u00e7u ta question\"\n\n12:22:50.086832\n   \u25c4\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 [PUSH]\n   \"Voici ma r\u00e9ponse :\"\n   \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n   \u2502 HTTP\/1.1 200 OK                 \u2502\n   \u2502 Date: Wed, 13 May 2026 ...      \u2502\n   \u2502 Content-Type: text\/html         \u2502\n   \u2502                                 \u2502\n   \u2502 <!DOCTYPE html>                 \u2502\n   \u2502 <html>...                       \u2502\n   \u2502 <h1>Bonjour le monde !<\/h1>     \u2502\n   \u2502 <\/html>                         \u2502\n   \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n\n12:22:50.086846\n   [ACK] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba\n   \"J'ai bien re\u00e7u ta r\u00e9ponse\"\n\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n\ud83d\udc4b LA FIN DE LA CONVERSATION\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n\n12:22:50.087099\n   [FIN] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba\n   \"Moi, je te quitte\"\n\n12:22:50.087186\n   \u25c4\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 [FIN]\n   \"Moi aussi, au revoir\"\n\n12:22:50.087207\n   [ACK] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25ba\n   \"OK, conversation termin\u00e9e\"<\/code><\/pre>\n\n\n\n
Un paquet TCP:<\/p>\n\n\n\n
Octet 0-1  : Port source      (16 bits = 2 octets)\nOctet 2-3  : Port destination (16 bits = 2 octets)\nOctet 4-7  : Num\u00e9ro de s\u00e9quence (32 bits = 4 octets)\nOctet 8-11 : Num\u00e9ro d'acquittement (32 bits = 4 octets)\nOctet 12   : Header length + r\u00e9serv\u00e9 (8 bits)\nOctet 13   : FLAGS (8 bits) \u2190 C'EST ICI QUE VOUS DEVEZ REGARDER !\nOctet 14-15: Fen\u00eatre (16 bits)\nOctet 16-17: Checksum (16 bits)\nOctet 18-19: Urgent pointer (16 bits)<\/code><\/pre>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
installer apache2 dans \/var\/www\/html\/index.html Page minimale Pour y acc\u00e9der, il faut contourner le proxy si il y un proxy Navigateur chromium, firefox, chrome , curl , nous allons utiliser ce dernier on obtient quelque chose comme cela : Dans un autre terminal on va espionner la communication on voit ainsi les trames tcp entre le […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_uag_custom_page_level_css":"","footnotes":""},"class_list":["post-8035","page","type-page","status-publish","hentry"],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false},"uagb_author_info":{"display_name":"admin","author_link":"https:\/\/workboot.fr\/ciela\/author\/admin\/"},"uagb_comment_info":0,"uagb_excerpt":"installer apache2 dans \/var\/www\/html\/index.html Page minimale Pour y acc\u00e9der, il faut contourner le proxy si il y un proxy Navigateur chromium, firefox, chrome , curl , nous allons utiliser ce dernier on obtient quelque chose comme cela : Dans un autre terminal on va espionner la communication on voit ainsi les trames tcp entre le\u2026","_links":{"self":[{"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/pages\/8035","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/comments?post=8035"}],"version-history":[{"count":12,"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/pages\/8035\/revisions"}],"predecessor-version":[{"id":8059,"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/pages\/8035\/revisions\/8059"}],"wp:attachment":[{"href":"https:\/\/workboot.fr\/ciela\/wp-json\/wp\/v2\/media?parent=8035"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}