Mode Transport entre deux stations GNU/Linux

Préambule

Synoptique

Installation

Alice et Bob

root@host:~# apt-get install ipsec-tools

Configuration sans IKE (manual keyed) avec AH + ESP


Génération de clés de longueur 128 et 192 bit :

$ dd if=/dev/random count=16 bs=1| xxd -ps
a9b3d99cd41ed7bc51e1a007c1ccc97f
16+0 enregistrements lus
16+0 enregistrements écrits

$ dd if=/dev/random count=24 bs=1| xxd -ps
2d619f669e2a93d69c286546bf3f8c2cc22853eac945ed06
24+0 enregistrements lus
24+0 enregistrements écrits
					

Alice

/etc/setkey.conf

#!/usr/sbin/setkey -f 

## Flush the SAD and SPD 
# 
flush; 
spdflush; 

## AH security association (SA) 
#alice et bob 
add 192.168.0.84 192.168.0.95 ah 10000 -A hmac-md5 "1234567890123456"; 
add 192.168.0.95 192.168.0.84 ah 20000 -A hmac-md5 "1234567890123456"; 

#ESP 
#alice et bob 
add 192.168.0.84 192.168.0.95 esp 10001 -E 3des-cbc 0x2d619f669e2a93d69c286546bf3f8c2cc22853eac945ed06; 
#on peut choisir des clés différentes (entre Alice et Bob et Bob et Alice) :
add 192.168.0.95 192.168.0.84 esp 20001 -E 3des-cbc "123456789012345678901234"; 

## security policy 
#alice et bob 
spdadd 192.168.0.84 192.168.0.95 any -P out ipsec 
	esp/transport//require
	ah/transport//require;
spdadd 192.168.0.95 192.168.0.84 any -P in ipsec 
	esp/transport//require
	ah/transport//require;
							

Explications :

Quelques algorithmes AH et ESP supportés :

Bob

/etc/setkey.conf

#!/usr/sbin/setkey -f 

## Flush the SAD and SPD 
# 
flush; 
spdflush; 

## AH security association (SA) 
add 192.168.0.84 192.168.0.95 ah 10000 -A hmac-md5 "1234567890123456"; 
add 192.168.0.84 192.168.0.95 esp 10001 -E 3des-cbc 0x9d6c4a8275ab12fbfdcaf01f0ba9dcfb5f424c878e97f888; 
add 192.168.0.95 192.168.0.84 ah 20000 -A hmac-md5 "1234567890123456"; 
add 192.168.0.95 192.168.0.84 esp 20001 -E 3des-cbc "123456789012345678901234"; 

spdadd 192.168.0.95 192.168.0.84 any -P out ipsec 
	esp/transport//require 
	ah/transport//require;
spdadd 192.168.0.84 192.168.0.95 any -P in ipsec 
	esp/transport//require
	ah/transport//require;

Vérification depuis le pont avec la commande tcpdump

tcpdump -i br0

On peut voir que les trames qui traversent notre pont comportent bien les champs ESP et AH.

root@host:~# tcpdump -i br0
11:59:39.230708 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x68d): ESP(spi=0x00004e21,seq=0x68d), length 88 
11:59:39.328125 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x746): ESP(spi=0x00002711,seq=0x746), length 88 
11:59:39.328307 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x68e): ESP(spi=0x00004e21,seq=0x68e), length 88 
11:59:40.230594 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x747): ESP(spi=0x00002711,seq=0x747), length 88 
11:59:40.230949 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x68f): ESP(spi=0x00004e21,seq=0x68f), length 88 
11:59:40.327423 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x748): ESP(spi=0x00002711,seq=0x748), length 88 
11:59:40.327760 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x690): ESP(spi=0x00004e21,seq=0x690), length 88 
11:59:41.231482 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x749): ESP(spi=0x00002711,seq=0x749), length 88 
11:59:41.231717 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x691): ESP(spi=0x00004e21,seq=0x691), length 88 
11:59:41.326445 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x74a): ESP(spi=0x00002711,seq=0x74a), length 88 
11:59:41.326686 IP 192.168.0.95 > 192.168.0.84: AH(spi=0x00004e20,seq=0x692): ESP(spi=0x00004e21,seq=0x692), length 88 
11:59:42.230489 IP 192.168.0.84 > 192.168.0.95: AH(spi=0x00002710,seq=0x74b): ESP(spi=0x00002711,seq=0x74b), length 88

Commandes utiles

setkey -f /etc/ipsec-tools.conf
racoon -F -f /etc/racoon/racoon.conf
setkey -F
setkey -D
setkey -DP

Sommaire

Licence Creative Commons
This website http://shebangthedolphins.net is licensed to the public under a licence Creative Commons Attribution licence.
Contact :