ipresend - resend IP packets out to network
ipresend [ -EHPRSTX ] [ -d <device> ] [ -g
  <gateway> ] [ -m <MTU> ] [ -r
  <filename> ]
ipresend was designed to allow packets to be resent, once captured, back
  out onto the network for use in testing. ipresend supports a number of
  different file formats as input, including saved snoop/tcpdump binary data.
  - -d <interface>
- Set the interface name to be the name supplied. This is useful with the
      -P, -S, -T and -E options, where it is not otherwise
      possible to associate a packet with an interface. Normal "text
      packets" can override this setting.
- -g <gateway>
- Specify the hostname of the gateway through which to route packets. This
      is required whenever the destination host isn't directly attached to the
      same network as the host from which you're sending.
- -m <MTU>
- Specify the MTU to be used when sending out packets. This option allows
      you to set a fake MTU, allowing the simulation of network interfaces with
      small MTU's without setting them so.
- -r <filename>
- Specify the filename from which to take input. Default is stdin.
- -E
- The input file is to be text output from etherfind. The text formats which
      are currently supported are those which result from the following
      etherfind option combinations:
		etherfind -n
		etherfind -n -t
  - -H
- The input file is to be hex digits, representing the binary makeup of the
      packet. No length correction is made, if an incorrect length is put in the
      IP header.
- -P
- The input file specified by -i is a binary file produced using
      libpcap (i.e., tcpdump version 3). Packets are read from this file as
      being input (for rule purposes).
- -R
- When sending packets out, send them out "raw" (the way they came
      in). The only real significance here is that it will expect the link layer
      (i.e. ethernet) headers to be prepended to the IP packet being
    output.
- -S
- The input file is to be in "snoop" format (see RFC 1761).
      Packets are read from this file and used as input from any interface. This
      is perhaps the most useful input type, currently.
- -T
- The input file is to be text output from tcpdump. The text formats which
      are currently supported are those which result from the following tcpdump
      option combinations:
		tcpdump -n
		tcpdump -nq
		tcpdump -nqt
		tcpdump -nqtt
		tcpdump -nqte
  - -X
- The input file is composed of text descriptions of IP packets.
snoop(1m), tcpdump(8), etherfind(8c), ipftest(1), ipresend(1), iptest(1),
  bpf(4), dlpi(7p)
Not all of the input formats are sufficiently capable of introducing a wide
  enough variety of packets for them to be all useful in testing. If you find
  any, please send email to me at darrenr@pobox.com