{"id":295,"date":"2021-04-25T18:05:22","date_gmt":"2021-04-25T18:05:22","guid":{"rendered":"https:\/\/sirensecurity.io\/blog\/?p=295"},"modified":"2021-07-15T03:03:42","modified_gmt":"2021-07-15T03:03:42","slug":"port-knocking","status":"publish","type":"post","link":"https:\/\/sirensecurity.io\/blog\/port-knocking\/","title":{"rendered":"Port Knocking"},"content":{"rendered":"\n
\"\"
\n

S1REN<\/p>\n\n\n\n

And you thought there was nothing here.<\/p>\n<\/div><\/div>\n\n\n\n

Knock knock.
Who's there?<\/em><\/p>\n\n\n\n

\"\"

Nothing on the nmap scan? But you found a cool and strange sequence of numbers?
Lets try Port knocking.<\/em>

https:\/\/en.wikipedia.org\/wiki\/Port_knocking<\/a>
In computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of pre-specified closed ports. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specific port(s). A variant called single packet authorization (SPA) exists, where only a single \"knock\" is needed, consisting of an encrypted packet.

https:\/\/github.com\/pha5matis\/Pentesting-Guide\/blob\/master\/port_knocking.md<\/a>
When you \"knock<\/strong>\" on a port you are really just sending TCP-packets with SYN-flag<\/em> to that port. The closed port will then respond with a ACK\/RST<\/em>. This basically means that the host has received the TCP-packet and - it ACK<\/strong>nolwdge it, but responds with a Reset<\/em> (RST<\/strong>) flag.

RST<\/strong> just means that the port is closed<\/em>.

+ Nmap & Bash.<\/strong>
for x in 4000 5000 6000; do<\/code>
nmap -Pn --host-timeout<\/strong> 201 --max-retries<\/strong> 0 -p $x $IP;<\/code>
done<\/code>
ssh User@$IP -p <port><\/p>\n\n\n\n


+ Netcat.<\/strong>
nc 192.168.1.102 4000
nc 192.168.1.102 5000
nc 192.168.1.102 6000
nc 192.168.1.102 8888
ssh User@$IP -p <port><\/p>\n","protected":false},"excerpt":{"rendered":"

Knock knock.Who's there? Nothing on the nmap scan? But you found a cool and strange sequence of numbers?Lets try Port knocking. https:\/\/en.wikipedia.org\/wiki\/Port_knockingIn computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of pre-specified closed ports. Once a correct sequence of connection attempts […]<\/p>\n","protected":false},"author":1,"featured_media":296,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[41,43,44,42,40,4,34,45],"class_list":["post-295","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-s1ren","tag-attack","tag-nc","tag-netcat","tag-nmap","tag-port-knocking","tag-s1ren","tag-siren","tag-siren-security"],"_links":{"self":[{"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/posts\/295","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/comments?post=295"}],"version-history":[{"count":4,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/posts\/295\/revisions"}],"predecessor-version":[{"id":416,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/posts\/295\/revisions\/416"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/media\/296"}],"wp:attachment":[{"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/media?parent=295"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/categories?post=295"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sirensecurity.io\/blog\/wp-json\/wp\/v2\/tags?post=295"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}