[patch] Telnet encryption dissection
Ted Percival <[email protected]>
| Newsgroups | gmane.network.ethereal.devel |
|---|---|
| Message-ID | <[email protected]> |
I have updated the TELNET dissector to dissect encryption negotiation commands as specified by RFC 2946. The patch is made against a Subversion checkout of epan/dissectors/packet-telnet.c . I am not subscribed to the ethereal-dev mailing list, so please ensure replies are CCed to me directly. Cheers, -Ted Percival _______________________________________________ Ethereal-dev mailing list [email protected] http://www.ethereal.com/mailman/listinfo/ethereal-dev
ethereal-telnet-encryption.patch
(text/x-patch, 5 KB)
This patch adds dissection of TELNET encryption subcommands, as
specified by RFC 2946.
Patch by Ted Percival of Quest Software.
--- packet-telnet.c.SAVE 2006-05-17 12:56:56.000000000 +1000
+++ packet-telnet.c 2006-05-18 15:24:29.000000000 +1000
@@ -50,6 +50,9 @@
static int hf_telnet_auth_mod_enc = -1;
static int hf_telnet_auth_krb5_type = -1;
+static int hf_telnet_enc_cmd = -1;
+static int hf_telnet_enc_type = -1;
+
static gint ett_telnet = -1;
static gint ett_telnet_subopt = -1;
static gint ett_status_subopt = -1;
@@ -593,6 +596,50 @@
val_to_str(cmd, rfc_opt_vals, "Unknown (%u)"));
}
+#define TN_ENC_IS 0
+#define TN_ENC_SUPPORT 1
+#define TN_ENC_REPLY 2
+#define TN_ENC_START 3
+#define TN_ENC_END 4
+#define TN_ENC_REQUEST_START 5
+#define TN_ENC_REQUEST_END 6
+#define TN_ENC_ENC_KEYID 7
+#define TN_ENC_DEC_KEYID 8
+static const value_string enc_cmd_vals[] = {
+ { TN_ENC_IS, "IS" },
+ { TN_ENC_SUPPORT, "SUPPORT" },
+ { TN_ENC_REPLY, "REPLY" },
+ { TN_ENC_START, "START" },
+ { TN_ENC_END, "END" },
+ { TN_ENC_REQUEST_START, "REQUEST-START" },
+ { TN_ENC_REQUEST_END, "REQUEST-END" },
+ { TN_ENC_ENC_KEYID, "ENC_KEYID" },
+ { TN_ENC_DEC_KEYID, "DEC_KEYID" },
+ { 0, NULL }
+};
+
+#define TN_ENCTYPE_NULL 0
+#define TN_ENCTYPE_DES_CFB64 1
+#define TN_ENCTYPE_DES_OFB64 2
+#define TN_ENCTYPE_DES3_CFB64 3
+#define TN_ENCTYPE_DES3_OFB64 4
+#define TN_ENCTYPE_CAST5_40_CFB64 8
+#define TN_ENCTYPE_CAST5_40_OFB64 9
+#define TN_ENCTYPE_CAST128_CFB64 10
+#define TN_ENCTYPE_CAST128_OFB64 11
+static const value_string enc_type_vals[] = {
+ { TN_ENCTYPE_NULL, "NULL" },
+ { TN_ENCTYPE_DES_CFB64, "DES_CFB64" },
+ { TN_ENCTYPE_DES_OFB64, "DES_OFB64" },
+ { TN_ENCTYPE_DES3_CFB64, "DES3_CFB64" },
+ { TN_ENCTYPE_DES3_OFB64, "DES3_OFB64" },
+ { TN_ENCTYPE_CAST5_40_CFB64, "CAST5_40_CFB64" },
+ { TN_ENCTYPE_CAST5_40_OFB64, "CAST5_40_OFB64" },
+ { TN_ENCTYPE_CAST128_CFB64, "CAST128_CFB64" },
+ { TN_ENCTYPE_CAST128_OFB64, "CAST128_OFB64" },
+ { 0, NULL }
+};
+
#define TN_AC_IS 0
#define TN_AC_SEND 1
@@ -836,6 +883,79 @@
}
}
+/* This function only uses the octet in the buffer at 'offset' */
+static void dissect_encryption_type(tvbuff_t *tvb, int offset, proto_tree *tree) {
+ guint8 etype;
+ etype = tvb_get_guint8(tvb, offset);
+ proto_tree_add_uint(tree, hf_telnet_enc_type, tvb, offset, 1, etype);
+}
+
+static void
+dissect_encryption_subopt(packet_info *pinfo, const char *optname _U_, tvbuff_t *tvb, int offset, int len, proto_tree *tree)
+{
+ guint8 ecmd, key_first_octet;
+
+ ecmd = tvb_get_guint8(tvb, offset);
+ proto_tree_add_uint(tree, hf_telnet_enc_cmd, tvb, offset, 1, ecmd);
+
+ offset++;
+ len--;
+
+ switch(ecmd) {
+ case TN_ENC_IS:
+ case TN_ENC_REPLY:
+ /* encryption type, type-specific data ... */
+ if (len > 0) {
+ dissect_encryption_type(tvb, offset, tree);
+ offset++;
+ len--;
+ proto_tree_add_text(tree, tvb, offset, len, "Type-specific data");
+ }
+ break;
+
+ case TN_ENC_SUPPORT:
+ /* list of encryption types ... */
+ while (len > 0) {
+ dissect_encryption_type(tvb, offset, tree);
+ offset++;
+ len--;
+ }
+ break;
+
+ case TN_ENC_START:
+ /* keyid ... */
+ if (len > 0) {
+ key_first_octet = tvb_get_guint8(tvb, offset);
+ proto_tree_add_text(tree, tvb, offset, len, (key_first_octet == 0) ? "Default key" : "Key ID");
+ }
+ break;
+
+ case TN_ENC_END:
+ /* no data */
+ break;
+
+ case TN_ENC_REQUEST_START:
+ /* (optional) keyid */
+ if (len > 0)
+ proto_tree_add_text(tree, tvb, offset, len, "Key ID (advisory)");
+ break;
+
+ case TN_ENC_REQUEST_END:
+ /* no data */
+ break;
+
+ case TN_ENC_ENC_KEYID:
+ case TN_ENC_DEC_KEYID:
+ /* (optional) keyid - if not supplied, there are no more known keys */
+ if (len > 0)
+ proto_tree_add_text(tree, tvb, offset, len, "Key ID");
+ break;
+
+ default:
+ proto_tree_add_text(tree, tvb, offset, len, "Unknown command");
+ }
+}
+
static tn_opt options[] = {
{
"Binary Transmission", /* RFC 856 */
@@ -1108,7 +1228,7 @@
&ett_enc_subopt,
VARIABLE_LENGTH,
1,
- NULL /* XXX - fill me in */
+ dissect_encryption_subopt
},
{
"New Environment Option", /* RFC 1572 */
@@ -1151,7 +1271,7 @@
VARIABLE_LENGTH,
1,
dissect_comport_subopt
- },
+ }
};
@@ -1556,7 +1676,12 @@
{ &hf_telnet_auth_krb5_type,
{ "Command", "telnet.auth.krb5.cmd", FT_UINT8, BASE_DEC,
VALS(auth_krb5_types), 0, "Krb5 Authentication sub-command", HFILL }},
-
+ { &hf_telnet_enc_cmd,
+ { "Enc Cmd", "telnet.enc.cmd", FT_UINT8, BASE_DEC,
+ VALS(enc_cmd_vals), 0, "Encryption command", HFILL }},
+ { &hf_telnet_enc_type,
+ { "Enc Type", "telnet.enc.type", FT_UINT8, BASE_DEC,
+ VALS(enc_type_vals), 0, "Encryption type", HFILL }},
};
static gint *ett[] = {
&ett_telnet,
@@ -1596,7 +1721,7 @@
&ett_xauth_subopt,
&ett_charset_subopt,
&ett_rsp_subopt,
- &ett_comport_subopt,
+ &ett_comport_subopt
};
proto_telnet = proto_register_protocol("Telnet", "TELNET", "telnet");