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604 lines
20 KiB
Groff
604 lines
20 KiB
Groff
.\" This file contains sections of the tcpdump man page, to which the
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.\" following copyright applies --EKR
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.\" Copyright (c) 1987, 1988, 1989, 1990, 1991, 1992, 1994, 1995, 1996, 1997
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.\" The Regents of the University of California. All rights reserved.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that: (1) source code distributions
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.\" retain the above copyright notice and this paragraph in its entirety, (2)
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.\" distributions including binary code include the above copyright notice and
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.\" this paragraph in its entirety in the documentation or other materials
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.\" provided with the distribution, and (3) all advertising materials mentioning
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.\" features or use of this software display the following acknowledgement:
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.\" ``This product includes software developed by the University of California,
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.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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.\" the University nor the names of its contributors may be used to endorse
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.\" or promote products derived from this software without specific prior
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.\" written permission.
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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.\"
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.\" Copyright (C) 1999-2000 RTFM, Inc.
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.\" All Rights Reserved
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.\"
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.\" This package is a SSLv3/TLS protocol analyzer written by Eric Rescorla
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.\" <ekr\@rtfm.com> and licensed by RTFM, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\"
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.\" This product includes software developed by Eric Rescorla for
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.\" RTFM, Inc.
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.\"
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.\" 4. Neither the name of RTFM, Inc. nor the name of Eric Rescorla may be
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.\" used to endorse or promote products derived from this
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.\" software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY ERIC RESCORLA AND RTFM, INC. ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY SUCH DAMAGE.
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.TH SSLDUMP 1 "14th August 2023 - version 1.8"
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.SH NAME
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ssldump \- dump SSL traffic on a network
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.SH SYNOPSIS
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.na
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.B ssldump
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[
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.B \-aAdeFHjnNPqtTvxXyz
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] [
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.B \-i
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.I interface
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]
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.br
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.ti +8
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[
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.B \-k
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.I keyfile
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]
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[
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.B \-l
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.I sslkeylogfile
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]
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[
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.B \-p
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.I password
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]
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[
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.B \-r
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.I dumpfile
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]
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[
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.B \-w
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.I outputpcap
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]
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.br
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.ti +8
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[
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.B \-S
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.RI [\| crypto \||\| d \||\| ht \||\| H \||\| nroff \|]
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]
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[
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.I expression
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]
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.br
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.ad
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.SH DESCRIPTION
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.LP
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\fIssldump\fP is an SSL/TLS network protocol analyzer. It identifies
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TCP connections on the chosen network interface and attempts to
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interpret them as SSL/TLS traffic. When it identifies SSL/TLS
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traffic, it decodes the records and displays them in a textual
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form to stdout. If provided with the appropriate keying material,
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it will also decrypt the connections and display the application
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data traffic. It supports various version of SSL/TLS up to TLS version 1.3.
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It also includes support for JSON output or JA3 support.
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.LP
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\fIssldump\fP has been originally tested on FreeBSD, Linux, Solaris, and HP/UX. \fIssldump\fP has
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mainly a new build process and it's mainly tested on different Linux flavors. Since
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it's based on PCAP, it should work on most platforms. However, unlike
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tcpdump, \fIssldump\fP needs to be able to see both sides of the data
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transmission so you may have trouble using it with network taps such
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as SunOS nit that don't permit you to see transmitted data.
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.B Under SunOS with nit or bpf:
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To run
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.I ssldump
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you must have read access to
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.I /dev/nit
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or
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.IR /dev/bpf* .
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.B Under Solaris with dlpi:
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You must have read access to the network pseudo device, e.g.
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.IR /dev/le .
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.B Under HP-UX with dlpi:
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You must be root or it must be installed setuid to root.
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.B Under IRIX with snoop:
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You must be root or it must be installed setuid to root.
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.B Under Linux:
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You must be root or it must be installed setuid to root.
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.B Under Ultrix and Digital UNIX:
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Once the super-user has enabled promiscuous-mode operation using
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.IR pfconfig (8),
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any user may run
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.I ssldump
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.B Under BSD:
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You must have read access to
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.IR /dev/bpf* .
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.SH OPTIONS
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.TP
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.B \-a
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Print bare TCP ACKs (useful for observing Nagle behavior).
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.TP
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.B \-A
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Print all record fields (by default \fIssldump\fP chooses
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the most interesting fields).
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.TP
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.B \-d
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Display the application data traffic. This usually means
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decrypting it, but when -d is used \fIssldump\fP will also decode
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application data traffic \fIbefore\fP the SSL session initiates.
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This allows you to see HTTPS CONNECT behavior as well as
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SMTP STARTTLS. As a side effect, since \fIssldump\fP can't tell
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whether plaintext is traffic before the initiation of an
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SSL connection or just a regular TCP connection, this allows
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you to use \fIssldump\fP to sniff any TCP connection.
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\fIssldump\fP will automatically detect ASCII data and display it
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directly to the screen. non-ASCII data is displayed as hex
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dumps. See also -X.
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.TP
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.B \-e
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Print absolute timestamps instead of relative timestamps.
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.TP
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.B \-F
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Specify the number of packets after which a connection pool cleaning is performed (in packets, default: 100).
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.TP
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.B \-H
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Print the full SSL packet header.
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.TP
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.BI \-i " interface"
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Use \fIinterface\fP as the network interface on which to sniff SSL/TLS
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traffic.
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.TP
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.B \-j
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Switch output format to JSON. Only stdout is affected by this toggle.
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.TP
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.BI \-k " keyfile"
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Use \fIkeyfile\fP as the location of the SSL keyfile (OpenSSL format)
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Previous versions of \fIssldump\fP automatically looked in ./server.pem.
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Now you must specify your keyfile every time.
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.TP
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.BI \-l " sslkeylogfile"
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Use \fIsslkeylogfile\fP as the location of the SSLKEYLOGFILE
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(https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format).
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.TP
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.B \-n
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Don't try to resolve host names from IP addresses.
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.TP
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.B \-N
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Attempt to parse ASN.1 when it appears, such as in
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certificates and DNs.
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.TP
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.BI \-p " password"
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Use \fIpassword\fP as the SSL keyfile password.
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.TP
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.B \-P
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Don't put the interface into promiscuous mode.
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.TP
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.B \-q
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Don't decode any record fields beyond a single summary line. (quiet mode).
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.TP
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.BI \-r " file"
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Read data from \fIfile\fP instead of from the network.
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The old -f option still works but is deprecated and will
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probably be removed with the next version.
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.TP
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.BI \-S " [ " crypto " | " d " | " ht " | " H " ]"
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Specify SSL flags to \fIssldump\fP. These flags include:
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.RS
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.TP
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.I crypto
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Print cryptographic information.
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.TP
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.I d
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Print fields as decoded.
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.TP
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.I ht
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Print the handshake type.
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.TP
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.I H
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Print handshake type and highlights.
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.RE
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.TP
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.B \-t
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Specify the TTL for inactive connections referenced in the connection pool (in seconds, default: 100).
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.TP
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.B \-T
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Print the TCP headers.
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.TP
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.B \-v
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Display version and copyright information.
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.TP
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.BI \-w " outputpcap"
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Use \fIoutputpcap\fP as the destination for decrypted packets.
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.TP
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.B \-x
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Print each record in hex, as well as decoding it.
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.TP
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.B \-X
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When the -d option is used, binary data is automatically printed
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in two columns with a hex dump on the left and the printable characters
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on the right. -X suppresses the display of the printable characters,
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thus making it easier to cut and paste the hex data into some other
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program.
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.TP
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.B \-y
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Decorate the output for processing with nroff/troff. Not very
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useful for the average user.
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.TP
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.B \-z
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Add timestamp in front of TCP packet description (-T)
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.TP
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\fIexpression\fP
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.RS
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Selects what packets \fIssldump\fP will examine. Technically speaking,
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\fIssldump\fP supports the full expression syntax from PCAP and tcpdump.
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In fact, the description here is cribbed from the tcpdump man
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page. However, since \fIssldump\fP needs to examine full TCP streams,
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most of the tcpdump expressions will select traffic mixes
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that \fIssldump\fP will simply ignore. Only the expressions which
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don't result in incomplete TCP streams are listed here.
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.LP
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The \fIexpression\fP consists of one or more
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.IR primitives .
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Primitives usually consist of an
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.I id
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(name or number) preceded by one or more qualifiers. There are three
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different kinds of qualifier:
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.IP \fItype\fP
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qualifiers say what kind of thing the id name or number refers to.
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Possible types are
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.BR host ,
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.B net
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and
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.BR port .
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E.g., `host foo', `net 128.3', `port 20'. If there is no type
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qualifier,
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.B host
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is assumed.
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.IP \fIdir\fP
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qualifiers specify a particular transfer direction to and/or from
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.I id.
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Possible directions are
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.BR src ,
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.BR dst ,
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.B "src or dst"
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and
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.B "src and"
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.BR dst .
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E.g., `src foo', `dst net 128.3', `src or dst port ftp-data'. If
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there is no dir qualifier,
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.B "src or dst"
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is assumed.
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For `null' link layers (i.e. point to point protocols such as slip) the
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.B inbound
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and
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.B outbound
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qualifiers can be used to specify a desired direction.
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.LP
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More complex filter expressions are built up by using the words
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.BR and ,
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.B or
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and
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.B not
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to combine primitives. E.g., `host foo and not port ftp and not port ftp-data'.
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To save typing, identical qualifier lists can be omitted. E.g.,
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`tcp dst port ftp or ftp-data or domain' is exactly the same as
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`tcp dst port ftp or tcp dst port ftp-data or tcp dst port domain'.
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.LP
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Allowable primitives are:
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.IP "\fBdst host \fIhost\fR"
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True if the IPv4/v6 destination field of the packet is \fIhost\fP,
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which may be either an address or a name.
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.IP "\fBsrc host \fIhost\fR"
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True if the IPv4/v6 source field of the packet is \fIhost\fP.
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.IP "\fBhost \fIhost\fP
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True if either the IPv4/v6 source or destination of the packet is \fIhost\fP.
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Any of the above host expressions can be prepended with the keywords,
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\fBip\fP, \fBarp\fP, \fBrarp\fP, or \fBip6\fP as in:
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.in +.5i
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.nf
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\fBip host \fIhost\fR
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.fi
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.in -.5i
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which is equivalent to:
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.in +.5i
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.nf
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\fBether proto \fI\\ip\fB and host \fIhost\fR
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.fi
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.in -.5i
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If \fIhost\fR is a name with multiple IP addresses, each address will
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be checked for a match.
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.IP "\fBether dst \fIehost\fP
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True if the ethernet destination address is \fIehost\fP. \fIEhost\fP
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may be either a name from /etc/ethers or a number (see
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.IR ethers (3N)
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for numeric format).
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.IP "\fBether src \fIehost\fP
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True if the ethernet source address is \fIehost\fP.
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.IP "\fBether host \fIehost\fP
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True if either the ethernet source or destination address is \fIehost\fP.
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.IP "\fBgateway\fP \fIhost\fP
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True if the packet used \fIhost\fP as a gateway. I.e., the ethernet
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source or destination address was \fIhost\fP but neither the IP source
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nor the IP destination was \fIhost\fP. \fIHost\fP must be a name and
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must be found in both /etc/hosts and /etc/ethers. (An equivalent
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expression is
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.in +.5i
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.nf
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\fBether host \fIehost \fBand not host \fIhost\fR
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.fi
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.in -.5i
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which can be used with either names or numbers for \fIhost / ehost\fP.)
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This syntax does not work in IPv6-enabled configuration at this moment.
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.IP "\fBdst net \fInet\fR"
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True if the IPv4/v6 destination address of the packet has a network
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number of \fInet\fP. \fINet\fP may be either a name from /etc/networks
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or a network number (see \fInetworks(4)\fP for details).
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.IP "\fBsrc net \fInet\fR"
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True if the IPv4/v6 source address of the packet has a network
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number of \fInet\fP.
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.IP "\fBnet \fInet\fR"
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True if either the IPv4/v6 source or destination address of the packet has a network
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number of \fInet\fP.
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.IP "\fBnet \fInet\fR \fBmask \fImask\fR"
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True if the IP address matches \fInet\fR with the specific netmask.
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May be qualified with \fBsrc\fR or \fBdst\fR.
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Note that this syntax is not valid for IPv6 \fInet\fR.
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.IP "\fBnet \fInet\fR/\fIlen\fR"
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True if the IPv4/v6 address matches \fInet\fR a netmask \fIlen\fR bits wide.
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May be qualified with \fBsrc\fR or \fBdst\fR.
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.IP "\fBdst port \fIport\fR"
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True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has a
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destination port value of \fIport\fP.
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The \fIport\fP can be a number or a name used in /etc/services (see
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.IR tcp (4P)
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and
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.IR udp (4P)).
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If a name is used, both the port
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number and protocol are checked. If a number or ambiguous name is used,
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only the port number is checked (e.g., \fBdst port 513\fR will print both
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tcp/login traffic and udp/who traffic, and \fBport domain\fR will print
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both tcp/domain and udp/domain traffic).
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.IP "\fBsrc port \fIport\fR"
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True if the packet has a source port value of \fIport\fP.
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.IP "\fBport \fIport\fR"
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True if either the source or destination port of the packet is \fIport\fP.
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Any of the above port expressions can be prepended with the keywords,
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\fBtcp\fP or \fBudp\fP, as in:
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.in +.5i
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.nf
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\fBtcp src port \fIport\fR
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.fi
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.in -.5i
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which matches only tcp packets whose source port is \fIport\fP.
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.LP
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Primitives may be combined using:
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.IP
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A parenthesized group of primitives and operators
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(parentheses are special to the Shell and must be escaped).
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.IP
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Negation (`\fB!\fP' or `\fBnot\fP').
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.IP
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Concatenation (`\fB&&\fP' or `\fBand\fP').
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.IP
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Alternation (`\fB||\fP' or `\fBor\fP').
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.LP
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Negation has highest precedence.
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Alternation and concatenation have equal precedence and associate
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left to right. Note that explicit \fBand\fR tokens, not juxtaposition,
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are now required for concatenation.
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.LP
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If an identifier is given without a keyword, the most recent keyword
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is assumed.
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For example,
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.in +.5i
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.nf
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\fBnot host vs and ace\fR
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.fi
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.in -.5i
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is short for
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.in +.5i
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.nf
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\fBnot host vs and host ace\fR
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.fi
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.in -.5i
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which should not be confused with
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.in +.5i
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.nf
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\fBnot ( host vs or ace )\fR
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.fi
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.in -.5i
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.LP
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|
Expression arguments can be passed to \fIssldump\fP as either a single argument
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or as multiple arguments, whichever is more convenient.
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Generally, if the expression contains Shell metacharacters, it is
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easier to pass it as a single, quoted argument.
|
|
Multiple arguments are concatenated with spaces before being parsed.
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|
.SH EXAMPLES
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.LP
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To listen to traffic on interface \fIle0\fP port \fI443\fP:
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.RS
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.nf
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\fBssldump -i le0 port 443\fP
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.fi
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.RE
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.LP
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|
To listen to traffic to the server \fIromeo\fP on port \fI443\fP:
|
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.RS
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.nf
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\fBssldump -i le0 port 443 and host romeo\fP:
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.fi
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.RE
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.LP
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|
To switch output format to JSON:
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.RS
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.nf
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\fBssldump -ANH -j -i le0 port 443 and host romeo\fP
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.fi
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.RE
|
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.LP
|
|
To decrypt traffic to host \fIromeo\fR
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|
\fIserver.pem\fR and the password \fIfoobar\fR:
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.RS
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.nf
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\fBssldump -Ad -k ~/server.pem -p foobar -i le0 host romeo
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|
.fi
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|
.RE
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.SH OUTPUT FORMAT
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.LP
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|
All output is printed to standard out.
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.LP
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|
\fIssldump\fP prints an indication of every new TCP connection using a line
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|
like the following
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|
.nf
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|
.LP
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|
\fBNew TCP connection #2: iromeo.rtfm.com(2302) <-> sr1.rtfm.com(4433)\fP
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|
.LP
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|
.fi
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|
The host which send the first SYN is printed on the left and the host
|
|
which responded is printed on the right. Ordinarily, this means that
|
|
the SSL client will be printed on the left with the SSL server on the
|
|
right. In this case we have a connection from \fIiromeo.rtfm.com\fR (port \fI2303\fR)
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|
to \fIsr1.rtfm.com\fR (port \fI4433\fR). To allow the user to disentangle
|
|
traffic from different connections, each connection is numbered. This is
|
|
connection \fI2\fR.
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|
.LP
|
|
The printout of each SSL record begins with a record line. This
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|
line contains the connection and record number, a timestamp, and the
|
|
record type, as in the following:
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|
.LP
|
|
.nf
|
|
\fB2 3 0.2001 (0.0749) S>C Handshake Certificate\fR
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|
.fi
|
|
.LP
|
|
This is record \fI3\fR on connection \fI2\fR. The first timestamp
|
|
is the time since the beginning of the connection. The second is
|
|
the time since the previous record. Both are in seconds.
|
|
.LP
|
|
The next field in the record line is the direction that the record
|
|
was going. \fIC>S\fR indicates records transmitted from client to
|
|
server and \fIS>C\fR indicates records transmitted from server to client.
|
|
\fIssldump\fP assumes that the host to transmit the first SYN
|
|
is the SSL client (this is nearly always correct).
|
|
.LP
|
|
The next field is the record type, one of \fIHandshake\fR, \fIIAlert\fR,
|
|
\fIChangeCipherSpec\fR, or \fIapplication_data\fR. Finally, \fIssldump\fP
|
|
may print record-specific data on the rest of the line. For \fIHandshake\fR
|
|
records, it prints the handshake message. Thus, this record is
|
|
a \fICertificate\fR message.
|
|
.LP
|
|
\fIssldump\fP chooses certain record types for further decoding. These
|
|
are the ones that have proven to be most useful for debugging:
|
|
.LP
|
|
.nf
|
|
\fIClientHello\fR \- version, offered cipher suites, session id
|
|
if provided)
|
|
\fIServerHello\fR \- version, session_id, chosen cipher suite,
|
|
compression method
|
|
\fIAlert\fR \- type and level (if obtainable)
|
|
.fi
|
|
.LP
|
|
Fuller decoding of the various records can be obtained by using the
|
|
.B \-A
|
|
,
|
|
.B \-d
|
|
,
|
|
.B \-k
|
|
and
|
|
.B \-p
|
|
flags.
|
|
.LP
|
|
.SH SIGNALS
|
|
.LP
|
|
When it receives SIGUSR1,
|
|
.B ssldump
|
|
prints the list of currently tracked connection on stderr.
|
|
.LP
|
|
With SIGUSR2,
|
|
.B ssldump
|
|
purges its internal connection tracking data structures.
|
|
.LP
|
|
.SH DECRYPTION
|
|
.LP
|
|
\fIssldump\fP can decrypt traffic between two hosts if the following two
|
|
conditions are met:
|
|
.RS
|
|
.nf
|
|
1. \fIssldump\fP has the keys.
|
|
2. Static RSA was used.
|
|
.fi
|
|
.RE
|
|
In any other case, once encryption starts,
|
|
\fIssldump\fP will only be able to determine the
|
|
record type. Consider the following section of a trace.
|
|
.LP
|
|
.nf
|
|
\fB1 5 0.4129 (0.1983) C>S Handshake ClientKeyExchange
|
|
1 6 0.4129 (0.0000) C>S ChangeCipherSpec
|
|
1 7 0.4129 (0.0000) C>S Handshake
|
|
1 8 0.5585 (0.1456) S>C ChangeCipherSpec
|
|
1 9 0.6135 (0.0550) S>C Handshake
|
|
1 10 2.3121 (1.6986) C>S application_data
|
|
1 11 2.5336 (0.2214) C>S application_data
|
|
1 12 2.5545 (0.0209) S>C application_data
|
|
1 13 2.5592 (0.0046) S>C application_data
|
|
1 14 2.5592 (0.0000) S>C Alert\fP
|
|
.fi
|
|
.LP
|
|
Note that the \fIClientKeyExchange\fR message type is printed
|
|
but the rest of the \fIHandshake\fR messages do not have
|
|
types. These are the \fIFinished\fR messages, but because they
|
|
are encrypted \fIssldump\fP only knows that they are of type \fIHandshake\fR.
|
|
Similarly, had the \fIAlert\fR in record 14 happened during the handshake,
|
|
it's type and level would have been printed. However, since it
|
|
is encrypted we can only tell that it is an alert.
|
|
.LP
|
|
.SH BUGS
|
|
.LP
|
|
Please send bug reports to https://github.com/adulau/ssldump
|
|
.LP
|
|
The TCP reassembler is not perfect. No attempt is made to reassemble IP
|
|
fragments and the 3-way handshake and close handshake are imperfectly
|
|
implemented. In practice, this turns out not to be much of a problem.
|
|
.LP
|
|
Support is provided for only for Ethernet and loopback interfaces
|
|
because that's all that I have. If you have another kind of network
|
|
you will need to modify pcap_cb in base/pcap-snoop.c. If you have
|
|
direct experience with \fIssldump\fP on other networks, please send me patches.
|
|
.LP
|
|
\fIssldump\fP doesn't implement session caching and therefore can't decrypt
|
|
resumed sessions.
|
|
.LP
|
|
.SH SEE ALSO
|
|
.LP
|
|
.BR tcpdump (1)
|
|
.LP
|
|
.SH AUTHOR
|
|
.LP
|
|
\fIssldump\fP was originally written by Eric Rescorla <ekr@rtfm.com>. Maintained by a bunch of volunteers, see https://github.com/adulau/ssldump/blob/master/CREDITS - Copyright (C) 2015-2023 the aforementioned volunteers
|