SSLTap - manual
Author: Steve Parkinson

# SSLTap Manual page

### Summary

A command-line proxy which is SSL-aware. It snoops on TCP connections, and displays the data going by, including SSL records and handshaking if the connection is SSL.

### Synopsis

`ssltap [-vhfsxl] [-p port] hostname:port`

`-v [prints version string]`
`-h [outputs hex instead of ASCII]`
`-f [turn on Fancy HTML coloring]`
`-s [turn on SSL decoding]`
`-x [turn on extra SSL hex dumps]`
`-p port [specify rendezvous port (default 1924)]`
`-l [loop - continue to wait for more connections]`

### Description

SSLTap opens a socket on a rendezvous port, and waits for an incoming connection (client side). Once this connection arrives, SSLTap makes another connection to hostname:port (server side). It passes any data sent by the client to the server, and vice versa. However, SSLTap will also display the data to the console. It can do this for plain HTTP connections, or any TCP protocol. However, SSLTap can also work with SSL streams, as detailed below.

Let's assume your development machine is called 'intercept'. The simplest usage of SSLTap is to run the command `'ssltap www.netscape.com:80'` on intercept. The program will wait for an incoming connection on port 1924. Next you would want to go to your browser, and enter the URL http://intercept:1924. The page retrieved by the browser will actually be gotten from the server at www.netscape.com, but will go via SSLTap.

Data sent from the client to the server is surrounded by a '--> [ ]' symbol, and data sent from the server to the client, a '<---[ ]' symbol.

You'll notice that the page retrieved with this example looks incomplete. This is because SSLTap by default closes down after the first connection is complete, so the browser is not able to load images. To make the SSLTap continue to accept connections, switch on looping mode with the -l option.

You can change the default rendezvous port to something else with the -p option.

The remaining options change the way the output is produced.

The -f option prints 'fancy' output - in colored HTML. Data sent from the client to the server is in blue. The server's reply is in red. This is designed so you can load the output up into a browser. When used with looping mode, the different connections are separated with horizontal lines.

-x will turn on HEX printing. Instead of being output as ascii, the data is shown as Hex, like this:

`<-- [`
`0: 56 d5 16 3e a1 6b b1 4a 8f 67 c4 d7 21 2f 6f dd | V..>.k.J.g..!/o.`
`10: bb 22 c4 75 8c f4 ce 28 16 a6 20 aa fb 9a 59 a1 | .".u...(.. ...Y.`
`20: 51 91 14 d2 fc 9f a7 ea 4d 9c f7 3a 9d 83 62 4a | Q.......M..:..bJ`
`]`

#### SSL Parse mode

The following options deal with SSL connections.

-s will turn on SSL parsing. (SSLTap doesn't automatically detect SSL sessions.)
-x will turn on extra SSL hexdumps. Mostly, if SSL can decode the data, it doesn't display the hex.

The following SSL3 Data structures are parsed: Handshake, ClientHello, ServerHello, CertificateChain, Certificate. In addition, SSL2 ClientHello, ServerHello, ClientMasterKey are also partly parsed. NO DECRYPTION IS PERFORMED ON THE DATA. SSLTAP CANNOT DECRYPT the data.

If a certificate chain is detected, DER-encoded certificates will be saved into files in the current directory called 'cert.0x' where x is the sequence number of the certificate.

### Operation Hints

Often, you'll find that the server certificate does not get transferred, or other parts of the handshake do not happen. This is because the browser is taking advantage of session-id-reuse (using the handshake results from a previous session). If you restart the browser, it'll clear the session id cache.

If you run the ssltap on a different machine that the ssl server you're trying to connect to, the browser will complain that the host name you're trying to connect to is different to the certificate, but it will still let you connect, after showing you a dialog.

### Bugs

Please contact ssltap-support@netscape.com for bug reports.

### History

2.1 - First public release (March 1998)

### Other

For reference, here is a table of some well-known port numbers:

HTTP | 80
SMTP | 25
HTTPS | 443
FTP | 21
IMAPS | 993
NNTP | 119
NNTPS | 563