start.sh and requirements improvements & no moduli fail fix with key exchanges (#194)

* Extra arguments to start.sh and improved requirements doc

Added possibly to pass extra arguments to twistd in start.sh (e.g. `env XARGS=--nodaemon ./start.sh`). Fixed list of the dependencies based on the issue micheloosterhof/cowrie#132 and added example of dependencies in practice for alpine:3.4.

* Fixes no moduli fail with key exchanges

Tries to fix issue micheloosterhof/cowrie#193

* Missing requirement and fixed logging

README.md

@@ -29,12 +29,20 @@ Software required:
 * An operating system (tested on Debian, CentOS, FreeBSD and Windows 7)
 * Python 2.7+
 * Twisted 8.0+
-* python-crypto
+* python-cryptography
 * python-pyasn1
 * python-gmpy2 (recommended)
 * python-mysqldb (for MySQL output)
 * Zope Interface 3.6.0+
 
+### Example requirements in alpine 3.4
+
+```
+apk add python py-asn1 py-twisted py-zope-interface libffi-dev \
+        py-cryptography py-pip py-six py-cffi py-idna py-ipaddress py-openssl
+pip install enum34
+```
+
 ## Files of interest:
 
 * `cowrie.cfg` - Cowrie's configuration file. Default values can be found in `cowrie.cfg.dist`

cowrie/ssh/transport.py

@@ -143,9 +143,13 @@ class HoneyPotSSHFactory(factory.SSHFactory):
 
         if not self.primes:
             ske = t.supportedKeyExchanges[:]
-            ske.remove('diffie-hellman-group-exchange-sha1')
+            if 'diffie-hellman-group-exchange-sha1' in ske:
+                ske.remove('diffie-hellman-group-exchange-sha1')
+                log.msg("No moduli, no diffie-hellman-group-exchange-sha1")
+            if 'diffie-hellman-group-exchange-sha256' in ske:
+                ske.remove('diffie-hellman-group-exchange-sha256')
+                log.msg("No moduli, no diffie-hellman-group-exchange-sha256")
             t.supportedKeyExchanges = ske
-            log.msg("No moduli, disabled diffie-hellman-group-exchange-sha1")
 
         # Reorder supported ciphers to resemble current openssh more
         t.supportedCiphers = ['aes128-ctr', 'aes192-ctr', 'aes256-ctr',
@@ -312,4 +316,3 @@ class HoneyPotTransport(transport.SSHServerTransport, TimeoutMixin):
             log.msg('[SERVER] - Disconnecting with error, code %s\nreason: %s'
                 % (reason, desc))
             self.transport.loseConnection()
-

start.sh

@@ -25,10 +25,10 @@ then
     . $VENV/bin/activate
 fi
 
-echo "Starting cowrie in the background..."
+echo "Starting cowrie with extra arguments [$XARGS] ..."
 if [ $AUTHBIND_ENABLED = "no" ]
 then
-    twistd -l log/cowrie.log --umask 0077 --pidfile cowrie.pid cowrie
+    twistd $XARGS -l log/cowrie.log --umask 0077 --pidfile cowrie.pid cowrie
 else
-    authbind --deep twistd -l log/cowrie.log --umask 0077 --pidfile cowrie.pid cowrie
+    authbind --deep twistd $XARGS -l log/cowrie.log --umask 0077 --pidfile cowrie.pid cowrie
 fi