Hello, I saw this e-mall address at http://ppp.samba.org/resources.html. We do have some questions about ppp. About ppp compression, to be more specific. We need to decompress the payload of some packets to verify if they are encrypted on Android devices. We configured a PPTP VPN server with no encryption. The compression algorithm negotiated during the connection phase is Deflate. For instance, in these packets 19:59:09.883213 IP 191.10.97.74 > 200.129.43.196: GREv1, call 1152, seq 106, length 51: compressed PPP data 0x0000: 4500 0047 cc42 4000 402f 59ab bf0a 614a 0x0010: c881 2bc4 3001 880b 0027 0480 0000 006a 0x0020: ff03 00fd 005c 02f7 1e3f 8327 ce85 cfc1 0x0030: 13e8 4b86 80ff 8d1c 6eb0 dee3 7f23 e4de 0x0040: e3ef 4258 ef11 00 19:59:09.884437 IP 191.10.97.74 > 200.129.43.196: GREv1, call 1152, seq 107, length 43: compressed PPP data 0x0000: 4500 003f cc43 4000 402f 59b2 bf0a 614a 0x0010: c881 2bc4 3001 880b 001f 0480 0000 006b 0x0020: ff03 00fd 005d 026b 5e04 4edd 294b e09a 0x0030: 5f31 04e8 0547 0ac0 34d7 4fc3 ae19 00 19:59:09.885609 IP 191.10.97.74 > 200.129.43.196: GREv1, call 1152, seq 108, length 44: compressed PPP data 0x0000: 4500 0040 cc44 4000 402f 59b0 bf0a 614a 0x0010: c881 2bc4 3001 880b 0020 0480 0000 006c 0x0020: ff03 00fd 005e 026b 3e06 ae27 1c56 c035 0x0030: bf66 0858 c168 ab03 d3ac 781a bb66 0000 We figured out that hex FD means that the payload is compressed. Then comes a coherency counter (fd 005c, fd 005d, fd 005e). And then, the compressed payload itself. Is there a way to call the deflate algorithm implemented on the linux kernel? Are we following the right path? We're trying to avoid implementing Deflate from zero. Thank you -- To unsubscribe from this list: send the line "unsubscribe linux-ppp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
