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ipstrings - Reads strings from pcap dump files



ipstrings [-cefimnprstwvz] [interface]



ipstrings reads text strings from all traffic on a network interface or from a pcap format data file (produced by tcpdump and other programs).



Network interface to read data from.

-c <npacket>
Terminate program after reading <npacket> packets.

Print source and destination ethernet address with each string.

Filter incoming packets according to filter string. For example,

   ipstrings -f "host" eth0

will pass the string "host" to the pcap library's filter routine. Thus ipstrings will only see packets with in one of the two ip addresses. The filter commands are extensive and are explained fully in the tcpdump man page.

Note that if you are trying to observe vlan traffic with your filter, you will have to specify the 'vlan' filter before other filters. In fact if all your traffic was vlan tagged, the command above would filter out all traffic, because the 'vlan' specifier was not included. To see vlan traffic the example above would need to change to

   ipaudit -f "vlan and host" eth0

Print source and destination ip address with each string.

Do not enter promiscuous mode when reading network interface.

-n <nchar>
Consider strings to be any set of printable characters (ASCII 32 to 126) <NCHAR> characters long or greater. When <NCHAR> is set to zero, then only those sets of printable characters which are terminated by an ASCII 0 are printed.

Print protocol number, source and destination port number for packets for each string printed. If protocol number is not 6 or 17 (tcp or udp) then port values are printed as 0.

-r <dumpfile>
Reads network info from <dumpfile> instead of reading live from network. Such a dumpfile could have been produced by the programs ipstrings, tcpdump or ethereal (http://www.zing.org). You can read from standard input using '-' as the file name, this feature is provided by the pcap libarary.

-s <nlen>
Read no more than first <nlen> packet bytes. Default is 96, minimum is 68.

Write packet time in format HH:MM:SS.SSSS for string printed.

-w <dumpfile>
Writes first <nlen> bytes of every packet to <dumpfile> in pcap format (see -s option about <nlen>). Can later be read by programs such as ipaudit, ipstrings, tcpdump or ethereal, Use '-' to write to standard out (this is a feature provided by the pcap library).

Print version information.

Write packet size in bytes (size of ip portion, does not include ethernet or other header).



To read strings from packets going by interface eth0
   ipstrings eth0

To read all strings from a pcap dump file 'pcap.dump'
   ipstrings -r pcap.dump

To read only for host
   ipstrings -r pcap.dump -f "host"

To read 'pcap.dump' only for host and port 21 (ftp)
   ipstrings -r pcap.dump -f "host and port 21"

To read gzip'ed 'pcap.dump.gz" for all hosts and only port 23 (telnet)
   zcat pcap.dump.gz | ipstrings -r- "port 23"



A short FTP session to was captured in pcap.file. When we give the command
   ipstrings -i -rpcap.fil

the output is   6     21   1323  220 bluebird FTP server (Versi   6   1323     21  USER jibe   6     21   1323  331 Password required for jibe   6   1323     21  PASS xxxxxxxx   6     21   1323  230 User jibe logged in.   6   1323     21  SYST   6     21   1323  215 UNIX Type: L8   6   1323     21  QUIT   6     21   1323  221-You have transferred 0 byt   6     21   1323  221-Total traffic for this ses

The first two columns are the source and destination ip addresses. Column three is the protocol, in this example all are 6 meaning all packets are tcp. Columns four and five are the source and destination port numbers. Starting in the sixth column are the printable strings that were found in the packets.



Report any to jon.rifkin@uconn.edu.






0.5 May 25, 2000



tcpdump(1) pcap(3) ipaudit(1)
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