SSLsplit is a tool for man-in-the-middle attacks against SSL/TLS encrypted network connections. Connections are transparently intercepted through a network address translation engine and redirected to SSLsplit. SSLsplit terminates SSL/TLS and initiates a new SSL/TLS connection to the original destination address, while logging all data transmitted. SSLsplit is intended to be useful for network forensics and penetration testing.
SSLsplit supports plain TCP, plain SSL, HTTP and HTTPS connections over both IPv4 and IPv6. For SSL and HTTPS connections, SSLsplit generates and signs forged X509v3 certificates on-the-fly, based on the original server certificate subject DN and subjectAltName extension. SSLsplit fully supports Server Name Indication (SNI) and is able to work with RSA, DSA and ECDSA keys and DHE and ECDHE cipher suites. Depending on the version of OpenSSL, SSLsplit supports SSL 3.0, TLS 1.0, TLS 1.1 and TLS 1.2, and optionally SSL 2.0 as well. SSLsplit can also use existing certificates of which the private key is available, instead of generating forged ones. SSLsplit supports NULL-prefix CN certificates and can deny OCSP requests in a generic way. For HTTP and HTTPS connections, SSLsplit removes response headers for HPKP in order to prevent public key pinning, for HSTS to allow the user to accept untrusted certificates, and Alternate Protocols to prevent switching to QUIC/SPDY.
See the manual page sslsplit(1) for details on using SSLsplit and setting up the various NAT engines.
SSLsplit depends on the OpenSSL and libevent 2.x libraries.
The build depends on GNU make and a POSIX.2 environment in
The optional unit tests depend on the check library.
SSLsplit currently supports the following operating systems and NAT mechanisms:
- FreeBSD: pf rdr and divert-to, ipfw fwd, ipfilter rdr
- OpenBSD: pf rdr-to and divert-to
- Linux: netfilter REDIRECT and TPROXY
- Mac OS X: pf rdr and ipfw fwd
make make test # optional unit tests make install # optional install
Dependencies are autoconfigured using pkg-config. If dependencies are not
picked up and fixing
PKG_CONFIG_PATH does not help, you can specify their
respective locations manually by setting
CHECK_BASE to the respective prefixes.
You can override the default install prefix (
/usr/local) by setting
For more build options see
SSLsplit is being developed on Github. For bug reports, please use the Github issue tracker. For patch submissions, please send me pull requests.
SSLsplit is provided under the simplified BSD license. SSLsplit contains components licensed under the MIT and APSL licenses. See the respective source file headers for details.
SSLsplit was inspired by
mitm-ssl by Claes M. Nyberg and
sslsniff by Moxie
Marlinspike, but shares no source code with them.
khash.h by Attractive Chaos.
The following individuals have contributed to the SSLsplit codebase by submitting patches or pull requests, in chronological order of first contribution:
- Daniel Roethlisberger (@droe), main author
- Steve Wills (@swills)
- Landon Fuller (@landonf)
- Wayne Jensen (@wjjensen)
See NEWS.md and
git log for details.