diff --git a/scapy/arch/linux.py b/scapy/arch/linux.py
index 6c7c8ed8e..da8e63f86 100644
--- a/scapy/arch/linux.py
+++ b/scapy/arch/linux.py
@@ -153,7 +153,7 @@ def attach_filter(s, bpf_filter, iface):
         )
         return
     nb = int(lines[0])
-    bpf = ""
+    bpf = b""
     for l in lines[1:]:
         bpf += struct.pack("HBBI", *(int(e) for e in l.split()))
 
diff --git a/scapy/automaton.py b/scapy/automaton.py
index d3ed29f86..35046e3a6 100644
--- a/scapy/automaton.py
+++ b/scapy/automaton.py
@@ -746,7 +746,7 @@ class Automaton(six.with_metaclass(Automaton_metaclass)):
                 self.cmdout.send(c)
             except Exception as e:
                 exc_info = sys.exc_info()
-                self.debug(3, "Transfering exception from tid=%i:\n%s"% (self.threadid, traceback.format_exc(exc_info)))
+                self.debug(3, "Transfering exception from tid=%i:\n%s"% (self.threadid, traceback.format_exception(*exc_info)))
                 m = Message(type=_ATMT_Command.EXCEPTION, exception=e, exc_info=exc_info)
                 self.cmdout.send(m)        
             self.debug(3, "Stopping control thread (tid=%i)"%self.threadid)
diff --git a/scapy/data.py b/scapy/data.py
index 435134d22..f8fe8614c 100644
--- a/scapy/data.py
+++ b/scapy/data.py
@@ -224,7 +224,7 @@ def load_manuf(filename):
                     lng=shrt
                 else:
                     lng = l[i+2:]
-                manufdb[oui] = shrt, lng
+                manufdb[oui] = plain_str(shrt), plain_str(lng)
             except Exception:
                 log_loading.warning("Couldn't parse one line from [%s] [%r]",
                                     filename, l, exc_info=True)
diff --git a/scapy/layers/dns.py b/scapy/layers/dns.py
index 98255cc50..a009486e5 100644
--- a/scapy/layers/dns.py
+++ b/scapy/layers/dns.py
@@ -34,8 +34,8 @@ class DNSStrField(StrField):
           return b"\x00"
 
         # Truncate chunks that cannot be encoded (more than 63 bytes..)
-        x = b"".join(chr(len(y)) + y for y in (k[:63] for k in x.split(".")))
-        if ord(x[-1]) != 0:
+        x = b"".join(chb(len(y)) + y for y in (k[:63] for k in x.split(".")))
+        if orb(x[-1]) != 0:
             x += b"\x00"
         return x
 
diff --git a/scapy/packet.py b/scapy/packet.py
index 7bed20c80..194a38d23 100644
--- a/scapy/packet.py
+++ b/scapy/packet.py
@@ -753,7 +753,8 @@ class Packet(six.with_metaclass(Packet_metaclass, BasePacket)):
 
     def hide_defaults(self):
         """Removes fields' values that are the same as default values."""
-        for k, v in self.fields.items():  # use .items(): self.fields is modified in the loop
+        for k in list(self.fields.keys()):  # use .items(): self.fields is modified in the loop
+            v = self.fields[k]
             if k in self.default_fields:
                 if self.default_fields[k] == v:
                     del self.fields[k]
diff --git a/scapy/utils.py b/scapy/utils.py
index c7022a7c5..175ee1dc5 100644
--- a/scapy/utils.py
+++ b/scapy/utils.py
@@ -33,7 +33,8 @@ from scapy.base_classes import BasePacketList
 ###########
 
 def get_temp_file(keep=False, autoext=""):
-    f = os.tempnam("","scapy")
+    with tempfile.NamedTemporaryFile(prefix="scapy") as _f:
+        f = _f.name
     if not keep:
         conf.temp_files.append(f+autoext)
     return f + autoext
@@ -55,7 +56,7 @@ def sane(x):
         if (j < 32) or (j >= 127):
             r=r+"."
         else:
-            r=r+i
+            r=r+chb(i)
     return r
 
 def lhex(x):
@@ -485,7 +486,7 @@ def do_graph(graph,prog=None,format=None,target=None,type=None,string=None,optio
     start_viewer=False
     if target is None:
         if WINDOWS:
-            tempfile = os.tempnam("", "scapy") + "." + format
+            tempfile = get_temp_file() + "." + format
             target = "> %s" % tempfile
             start_viewer = True
         else:
diff --git a/test/regression.uts b/test/regression.uts
index 6a73ed1ec..e54e2e93e 100644
--- a/test/regression.uts
+++ b/test/regression.uts
@@ -27,7 +27,7 @@ def test_list_contrib():
         list_contrib()
         result_list_contrib = cmco.get_output()
     assert("http2               : HTTP/2 (RFC 7540, RFC 7541)              status=loads" in result_list_contrib)
-    assert(result_list_contrib.split('\n') > 40)
+    assert(len(result_list_contrib.split('\n')) > 40)
 
 test_list_contrib()
 
@@ -94,7 +94,7 @@ else:
 
 if len(routes6):
     assert(len([r for r in routes6 if r[0] == "::1" and r[-1] == ["::1"]]) >= 1)
-    if iflist >= 2:
+    if len(iflist) >= 2:
         assert(len([r for r in routes6 if r[0] == "fe80::" and r[1] == 64]) >= 1)
         len([r for r in routes6 if in6_islladdr(r[0]) and r[1] == 128 and r[-1] == ["::1"]]) >= 1
 else:
@@ -262,8 +262,8 @@ Ether(dst="ff:ff:ff:ff:ff:ff", src="ff:ff:ff:ff:ff:ff", type=0x9000)
 assert _.mysummary() == 'ff:ff:ff:ff:ff:ff > ff:ff:ff:ff:ff:ff (0x9000)'
 
 = Test fletcher16_* functions
-assert(fletcher16_checksum("\x28\x07") == 22319)
-assert(fletcher16_checkbytes("ABCDEF", 2) == "\x89\x67")
+assert(fletcher16_checksum(b"\x28\x07") == 22319)
+assert(fletcher16_checkbytes(b"ABCDEF", 2) == "\x89\x67")
 
 = Test zerofree_randstring function
 random.seed(0x2807)
@@ -275,7 +275,7 @@ def test_export_import_object():
     with ContextManagerCaptureOutput() as cmco:
         export_object(2807)
         result_export_object = cmco.get_output()
-    assert(result_export_object.endswith("eNprYPL9zqUHAAdrAf8=\n\n"))
+    assert(result_export_object.endswith(b"eNprYPL9zqUHAAdrAf8=\n\n"))
     assert(import_object(result_export_object) == 2807)
 
 test_export_import_object()
@@ -285,11 +285,11 @@ tex_escape("$#_") == "\\$\\#\\_"
 
 = Test colgen function
 f = colgen(range(3))
-assert(len([f.next() for i in range(2)]) == 2)
+assert(len([next(f) for i in range(2)]) == 2)
 
 = Test incremental_label function
 f = incremental_label()
-assert([f.next() for i in range(2)] == ["tag00000", "tag00001"])
+assert([next(f) for i in range(2)] == ["tag00000", "tag00001"])
 
 = Test corrupt_* functions
 import random
@@ -309,7 +309,7 @@ assert(load_object(fname) == 2807)
 = Test whois function
 if not WINDOWS:
     result = whois("193.0.6.139")
-    assert("inetnum" in result and "Amsterdam" in result)
+    assert(b"inetnum" in result and b"Amsterdam" in result)
 
 = Test manuf DB methods
 ~ manufdb
@@ -351,7 +351,7 @@ assert a.next() == (3, 2, 3)
 
 saved_conf_verb = conf.verb
 fd, fname = tempfile.mkstemp()
-os.write(fd, "conf.verb = 42\n")
+os.write(fd, b"conf.verb = 42\n")
 os.close(fd)
 from scapy.main import _read_config_file
 _read_config_file(fname, globals(), locals())
@@ -671,9 +671,9 @@ x=SNMP(b'0y\x02\x01\x00\x04\x06public\xa2l\x02\x01)\x02\x01\x00\x02\x01\x000a0!\
 x.show()
 assert(x.community==b"public" and x.version == 0)
 assert(x.PDU.id == 41 and len(x.PDU.varbindlist) == 3)
-assert(x.PDU.varbindlist[0].oid == "1.3.6.1.4.1.253.8.64.4.2.1.7.10.14130104")
+assert(x.PDU.varbindlist[0].oid == b"1.3.6.1.4.1.253.8.64.4.2.1.7.10.14130104")
 assert(x.PDU.varbindlist[0].value == "172.31.19.2")
-assert(x.PDU.varbindlist[2].oid == "1.3.6.1.4.1.253.8.64.4.2.1.5.10.14130400")
+assert(x.PDU.varbindlist[2].oid == b"1.3.6.1.4.1.253.8.64.4.2.1.5.10.14130400")
 assert(x.PDU.varbindlist[2].value == 1)
 
 
@@ -891,7 +891,7 @@ def _send_or_sniff(pkt, timeout, flt, pid, fork, t_other=None):
             os.waitpid(pid, 0)
         else:
             t_other.join()
-    assert raw(pkt) in (str(p[pkt.__class__]) for p in pkts if pkt.__class__ in p)
+    assert raw(pkt) in (raw(p[pkt.__class__]) for p in pkts if pkt.__class__ in p)
 
 def send_and_sniff(pkt, timeout=2, flt=None):
     """Send a packet, sniff, and check the packet has been seen"""