iptraf-ng

IPTraf-ng gathers data like TCP connection packet and byte counts, interface statistics and activity indicators, TCP/UDP traffic breakdowns, and LAN station packet and byte counts. IPTraf-ng features include an IP traffic monitor which shows TCP flag information, packet and byte counts, ICMP details, OSPF packet types, and oversized IP packet warnings; interface statistics showing IP, TCP, UDP, ICMP, non-IP and other IP packet counts, IP checksum errors, interface activity and packet size counts; a TCP and UDP service monitor showing counts of incoming and outgoing packets for common TCP and UDP application ports, a LAN statistics module that discovers active hosts and displays statistics about their activity; TCP, UDP and other protocol display filters so you can view just the traffic you want; logging; support for Ethernet, FDDI, ISDN, SLIP, PPP, and loopback interfaces.