Hello, Following is the tcpdump output of part of an ftp connection on a FDDI host with Ethernet encapsulation. What I find odd about it is that the packet socket returns strange values for h->tp_len. Namely h->tp_len is always 2 * (ip->ip_len + 14). Where does factor 2 come from? I don't see factor 2 on a normal Ethernet host. 01:34:29.557910 0:2:b3:1f:ba:5d 0:0:cb:c0:84:22 ip 3028: Corona.47389 > Hell.ftp-data: . 2187169:2188617(1448) ack 1 win 5792 <nop,nop,timestamp 46444268 175817981> (DF) [tos 0x8] (ttl 64, id 1301, len 1500) 01:34:29.559210 0:2:b3:1f:ba:5d 0:0:cb:c0:84:22 ip 3028: Corona.47389 > Hell.ftp-data: . 2188617:2190065(1448) ack 1 win 5792 <nop,nop,timestamp 46444268 175817981> (DF) [tos 0x8] (ttl 64, id 1302, len 1500) 01:34:29.560443 0:2:b3:1f:ba:5d 0:0:cb:c0:84:22 ip 3028: Corona.47389 > Hell.ftp-data: . 2190065:2191513(1448) ack 1 win 5792 <nop,nop,timestamp 46444268 175817981> (DF) [tos 0x8] (ttl 64, id 1303, len 1500) ... 01:34:29.615479 0:2:b3:1f:ba:5d 0:0:cb:c0:84:22 ip 132: Corona.47389 > Hell.ftp-data: . [tcp sum ok] ack 2 win 5792 <nop,nop,timestamp 46444274 175817995> (DF) (ttl 64, id 0, len 52) Interface configuration with Linux 2.4.19: eth0 Link encap:Ethernet HWaddr 00:00:CB:C0:84:22 inet addr:141.X.Y.Z Bcast:141.X.Y.255 Mask:255.255.255.0 UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:569090565 errors:0 dropped:0 overruns:0 frame:0 TX packets:23566781 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:231659734 (220.9 Mb) TX bytes:2282823786 (2177.0 Mb) Interrupt:10 Base address:0xd400 Regards, -Udo.
Attachment:
pgp00036.pgp
Description: PGP signature