1. Is there a way to see a errors at Ethernet capture packets.
Unless the NIC driver can be told to hand packets with Ethernet FCS errors (which is what I assume you mean) off to libpcap, no. I don't know, offhand, whether there are any driver/OS combinations that will let you do so.
2. Is there a way to save the capture packets to file via command line?
the '-w' option, which is documented in the manpage. If you mean in some human-readable format, no; use tethereal -V and/or -x for that.
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Regards,
Marco.
