diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 8a3b77cb..446ebf0e 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -3,17 +3,18 @@
 # Please see the documentation for all configuration options:
 # https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
 
+---
 version: 2
 updates:
-  - package-ecosystem: "pip" # See documentation for possible values
-    directory: "/" # Location of package manifests
+  - package-ecosystem: "pip"  # See documentation for possible values
+    directory: "/"  # Location of package manifests
     schedule:
       interval: "weekly"
-  - package-ecosystem: "pip" # See documentation for possible values
-    directory: "/docs" # Location of package manifests
+  - package-ecosystem: "pip"  # See documentation for possible values
+    directory: "/docs"  # Location of package manifests
     schedule:
       interval: "weekly"
-  - package-ecosystem: "github-actions" # See documentation for possible values
-    directory: "/" # Location of package manifests
+  - package-ecosystem: "github-actions"  # See documentation for possible values
+    directory: "/"  # Location of package manifests
     schedule:
       interval: "weekly"
diff --git a/.github/workflows/tox.yml b/.github/workflows/tox.yml
index 1740b80c..07f78c71 100644
--- a/.github/workflows/tox.yml
+++ b/.github/workflows/tox.yml
@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12.0-rc.1", "pypy-3.8", "pypy-3.9", "pypy-3.10"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12.0-rc.1", "pypy-3.9", "pypy-3.10"]
     continue-on-error: ${{ matrix.python-version == '3.12.0-rc.1' }}
     steps:
       - uses: actions/checkout@v3
diff --git a/.readthedocs.yml b/.readthedocs.yml
index 25f6d44b..5d21f764 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -19,7 +19,7 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.11"
-  
+
 # Optionally Python version and requirements required to build your docs
 python:
   install:
diff --git a/requirements.txt b/requirements.txt
index db8d73f8..43655197 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,4 +10,4 @@ python-dateutil==2.8.2
 service_identity==23.1.0
 tftpy==0.8.2
 treq==22.2.0
-twisted==22.10.0
+twisted==23.8.0
diff --git a/src/backend_pool/pool_server.py b/src/backend_pool/pool_server.py
index 02d7201d..7ee2a450 100644
--- a/src/backend_pool/pool_server.py
+++ b/src/backend_pool/pool_server.py
@@ -92,9 +92,7 @@ class PoolServer(Protocol):
                         guest_id, guest_ip, ssh_port, telnet_port
                     )
 
-                    fmt = "!cIIH{}sHHH{}s".format(
-                        len(self.nat_public_ip), len(guest_snapshot)
-                    )
+                    fmt = f"!cIIH{len(self.nat_public_ip)}sHHH{len(guest_snapshot)}s"
                     response = struct.pack(
                         fmt,
                         b"r",
diff --git a/src/cowrie/commands/fs.py b/src/cowrie/commands/fs.py
index 26d29898..e523d324 100644
--- a/src/cowrie/commands/fs.py
+++ b/src/cowrie/commands/fs.py
@@ -371,9 +371,7 @@ or available locally via: info '(coreutils) rm invocation'\n"""
                 if i[fs.A_NAME] == basename:
                     if i[fs.A_TYPE] == fs.T_DIR and not recursive:
                         self.errorWrite(
-                            "rm: cannot remove `{}': Is a directory\n".format(
-                                i[fs.A_NAME]
-                            )
+                            f"rm: cannot remove `{i[fs.A_NAME]}': Is a directory\n"
                         )
                     else:
                         dir.remove(i)
@@ -456,7 +454,7 @@ class Command_cp(HoneyPotCommand):
                 dir = self.fs.get_path(os.path.dirname(resolv(dest)))
                 outfile = os.path.basename(dest.rstrip("/"))
             if outfile in [x[fs.A_NAME] for x in dir]:
-                dir.remove([x for x in dir if x[fs.A_NAME] == outfile][0])
+                dir.remove(next(x for x in dir if x[fs.A_NAME] == outfile))
             s[fs.A_NAME] = outfile
             dir.append(s)
 
diff --git a/src/cowrie/commands/ftpget.py b/src/cowrie/commands/ftpget.py
index 3a947467..61e27682 100644
--- a/src/cowrie/commands/ftpget.py
+++ b/src/cowrie/commands/ftpget.py
@@ -166,9 +166,7 @@ Download a file via FTP
         path = os.path.dirname(fakeoutfile)
         if not path or not self.fs.exists(path) or not self.fs.isdir(path):
             self.write(
-                "ftpget: can't open '{}': No such file or directory".format(
-                    self.local_file
-                )
+                f"ftpget: can't open '{self.local_file}': No such file or directory"
             )
             self.exit()
             return
@@ -250,9 +248,7 @@ Download a file via FTP
             ftp.connect(host=self.host, port=self.port, timeout=30)
         except Exception as e:
             log.msg(
-                "FTP connect failed: host={}, port={}, err={}".format(
-                    self.host, self.port, str(e)
-                )
+                f"FTP connect failed: host={self.host}, port={self.port}, err={e!s}"
             )
             self.write("ftpget: can't connect to remote host: Connection refused\n")
             return False
diff --git a/src/cowrie/commands/gcc.py b/src/cowrie/commands/gcc.py
index bf99cbef..cc361145 100644
--- a/src/cowrie/commands/gcc.py
+++ b/src/cowrie/commands/gcc.py
@@ -166,12 +166,10 @@ compilation terminated.\n"""
         version_short = ".".join([str(v) for v in Command_gcc.APP_VERSION[:2]])
 
         if short:
-            data = """{} (Debian {}-8) {}
+            data = f"""{Command_gcc.APP_NAME} (Debian {version}-8) {version}
 Copyright (C) 2010 Free Software Foundation, Inc.
 This is free software; see the source for copying conditions.  There is NO
-warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.""".format(
-                Command_gcc.APP_NAME, version, version
-            )
+warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."""
         else:
             data = """Using built-in specs.
 COLLECT_GCC=gcc
diff --git a/src/cowrie/commands/iptables.py b/src/cowrie/commands/iptables.py
index 3008fddd..eadd36ab 100644
--- a/src/cowrie/commands/iptables.py
+++ b/src/cowrie/commands/iptables.py
@@ -283,7 +283,7 @@ Perhaps iptables or your kernel needs to be upgraded.\n""".format(
         """
 
         self.write(
-            """{} {}'
+            f"""{Command_iptables.APP_NAME} {Command_iptables.APP_VERSION}'
 
 Usage: iptables -[AD] chain rule-specification [options]
        iptables -I chain [rulenum] rule-specification [options]
@@ -345,9 +345,7 @@ Options:
 [!] --fragment -f      match second or further fragments only
   --modprobe=<command>     try to insert modules using this command
   --set-counters PKTS BYTES    set the counter during insert/append
-[!] --version  -V      print package version.\n""".format(
-                Command_iptables.APP_NAME, Command_iptables.APP_VERSION
-            )
+[!] --version  -V      print package version.\n"""
         )
         self.exit()
 
diff --git a/src/cowrie/commands/perl.py b/src/cowrie/commands/perl.py
index 981ed113..97fe5cee 100644
--- a/src/cowrie/commands/perl.py
+++ b/src/cowrie/commands/perl.py
@@ -101,9 +101,7 @@ class Command_perl(HoneyPotCommand):
                 self.exit()
             else:
                 self.write(
-                    'Can\'t open perl script "{}": No such file or directory\n'.format(
-                        value
-                    )
+                    f'Can\'t open perl script "{value}": No such file or directory\n'
                 )
                 self.exit()
 
diff --git a/src/cowrie/commands/ssh.py b/src/cowrie/commands/ssh.py
index 799039b9..94a0bd1e 100644
--- a/src/cowrie/commands/ssh.py
+++ b/src/cowrie/commands/ssh.py
@@ -82,10 +82,8 @@ class Command_ssh(HoneyPotCommand):
                 self.ip = host
             else:
                 self.write(
-                    "ssh: Could not resolve hostname {}: \
-                    Name or service not known\n".format(
-                        host
-                    )
+                    f"ssh: Could not resolve hostname {host}: \
+                    Name or service not known\n"
                 )
                 self.exit()
         else:
@@ -98,10 +96,8 @@ class Command_ssh(HoneyPotCommand):
         self.user = user
 
         self.write(
-            "The authenticity of host '{} ({})' \
-            can't be established.\n".format(
-                self.host, self.ip
-            )
+            f"The authenticity of host '{self.host} ({self.ip})' \
+            can't be established.\n"
         )
         self.write(
             "RSA key fingerprint is \
@@ -112,10 +108,8 @@ class Command_ssh(HoneyPotCommand):
 
     def yesno(self, line: str) -> None:
         self.write(
-            "Warning: Permanently added '{}' (RSA) to the \
-            list of known hosts.\n".format(
-                self.host
-            )
+            f"Warning: Permanently added '{self.host}' (RSA) to the \
+            list of known hosts.\n"
         )
         self.write(f"{self.user}@{self.host}'s password: ")
         self.protocol.password_input = True
@@ -136,10 +130,8 @@ class Command_ssh(HoneyPotCommand):
             self.protocol.cwd = "/"
         self.protocol.password_input = False
         self.write(
-            "Linux {} 2.6.26-2-686 #1 SMP Wed Nov 4 20:45:37 \
-            UTC 2009 i686\n".format(
-                self.protocol.hostname
-            )
+            f"Linux {self.protocol.hostname} 2.6.26-2-686 #1 SMP Wed Nov 4 20:45:37 \
+            UTC 2009 i686\n"
         )
         self.write(f"Last login: {time.ctime(time.time() - 123123)} from 192.168.9.4\n")
         self.exit()
diff --git a/src/cowrie/commands/wget.py b/src/cowrie/commands/wget.py
index 6a4ebc40..d5362432 100644
--- a/src/cowrie/commands/wget.py
+++ b/src/cowrie/commands/wget.py
@@ -139,9 +139,7 @@ class Command_wget(HoneyPotCommand):
             path = os.path.dirname(self.outfile)  # type: ignore
             if not path or not self.fs.exists(path) or not self.fs.isdir(path):
                 self.errorWrite(
-                    "wget: {}: Cannot open: No such file or directory\n".format(
-                        self.outfile
-                    )
+                    f"wget: {self.outfile}: Cannot open: No such file or directory\n"
                 )
                 self.exit()
                 return
diff --git a/src/cowrie/core/credentials.py b/src/cowrie/core/credentials.py
index 88d75d5d..50821eb4 100644
--- a/src/cowrie/core/credentials.py
+++ b/src/cowrie/core/credentials.py
@@ -39,7 +39,7 @@ class IUsername(ICredentials):
     """
     Encapsulate username only
 
-    @type username: C{str}
+    @type username: C{bytes}
     @ivar username: The username associated with these credentials.
     """
 
@@ -48,10 +48,10 @@ class IUsernamePasswordIP(IUsernamePassword):
     """
     I encapsulate a username, a plaintext password and a source IP
 
-    @type username: C{str}
+    @type username: C{bytes}
     @ivar username: The username associated with these credentials.
 
-    @type password: C{str}
+    @type password: C{bytes}
     @ivar password: The password associated with these credentials.
 
     @type ip: C{str}
@@ -71,16 +71,16 @@ class PluggableAuthenticationModulesIP:
     Twisted removed IPAM in 15, adding in Cowrie now
     """
 
-    def __init__(self, username: str, pamConversion: Callable, ip: str) -> None:
-        self.username: str = username
+    def __init__(self, username: bytes, pamConversion: Callable, ip: str) -> None:
+        self.username: bytes = username
         self.pamConversion: Callable = pamConversion
         self.ip: str = ip
 
 
 @implementer(IUsername)
 class Username:
-    def __init__(self, username: str):
-        self.username: str = username
+    def __init__(self, username: bytes):
+        self.username: bytes = username
 
 
 @implementer(IUsernamePasswordIP)
@@ -89,10 +89,10 @@ class UsernamePasswordIP:
     This credential interface also provides an IP address
     """
 
-    def __init__(self, username: str, password: str, ip: str) -> None:
-        self.username: str = username
-        self.password: str = password
+    def __init__(self, username: bytes, password: bytes, ip: str) -> None:
+        self.username: bytes = username
+        self.password: bytes = password
         self.ip: str = ip
 
-    def checkPassword(self, password: str) -> bool:
+    def checkPassword(self, password: bytes) -> bool:
         return self.password == password
diff --git a/src/cowrie/output/abuseipdb.py b/src/cowrie/output/abuseipdb.py
index f651b29a..787107ba 100644
--- a/src/cowrie/output/abuseipdb.py
+++ b/src/cowrie/output/abuseipdb.py
@@ -358,7 +358,7 @@ class Reporter:
             "ip": ip,
             "categories": "18,22",
             "comment": "Cowrie Honeypot: Unauthorised SSH/Telnet login attempt "
-            'with user "{}" at {}'.format(uname, t),
+            f'with user "{uname}" at {t}',
         }
 
         self.http_request(params)
diff --git a/src/cowrie/output/influx.py b/src/cowrie/output/influx.py
index d11f837e..3763b035 100644
--- a/src/cowrie/output/influx.py
+++ b/src/cowrie/output/influx.py
@@ -54,10 +54,8 @@ class Output(cowrie.core.output.Output):
             match = re.search(r"^\d+[dhmw]{1}$", retention_policy_duration)
             if not match:
                 log.msg(
-                    (
                         "output_influx: invalid retention policy."
-                        "Using default '{}'.."
-                    ).format(retention_policy_duration)
+                        f"Using default '{retention_policy_duration}'.."
                 )
                 retention_policy_duration = retention_policy_duration_default
         else:
@@ -215,6 +213,6 @@ class Output(cowrie.core.output.Output):
 
         if not result:
             log.msg(
-                "output_influx: error when writing '{}' measurement"
-                "in the db.".format(eventid)
+                f"output_influx: error when writing '{eventid}' measurement"
+                "in the db."
             )
diff --git a/src/cowrie/python/logfile.py b/src/cowrie/python/logfile.py
index 49112c2b..718fe213 100644
--- a/src/cowrie/python/logfile.py
+++ b/src/cowrie/python/logfile.py
@@ -23,9 +23,7 @@ class CowrieDailyLogFile(logfile.DailyLogFile):
         Return the suffix given a (year, month, day) tuple or unixtime
         """
         try:
-            return "{:02d}-{:02d}-{:02d}".format(
-                tupledate[0], tupledate[1], tupledate[2]
-            )
+            return f"{tupledate[0]:02d}-{tupledate[1]:02d}-{tupledate[2]:02d}"
         except Exception:
             # try taking a float unixtime
             return "_".join(map(str, self.toDate(tupledate)))
diff --git a/src/cowrie/shell/fs.py b/src/cowrie/shell/fs.py
index 15c179d7..b47136d6 100644
--- a/src/cowrie/shell/fs.py
+++ b/src/cowrie/shell/fs.py
@@ -355,7 +355,7 @@ class HoneyPotFilesystem:
         _dir = self.get_path(_path)
         outfile: str = os.path.basename(path)
         if outfile in [x[A_NAME] for x in _dir]:
-            _dir.remove([x for x in _dir if x[A_NAME] == outfile][0])
+            _dir.remove(next(x for x in _dir if x[A_NAME] == outfile))
         _dir.append([outfile, T_FILE, uid, gid, size, mode, ctime, [], None, None])
         self.newcount += 1
         return True
diff --git a/src/cowrie/ssh/userauth.py b/src/cowrie/ssh/userauth.py
index 47033f4d..74188c59 100644
--- a/src/cowrie/ssh/userauth.py
+++ b/src/cowrie/ssh/userauth.py
@@ -29,7 +29,7 @@ class HoneyPotSSHUserAuthServer(userauth.SSHUserAuthServer):
     """
 
     bannerSent: bool = False
-    user: str
+    user: bytes
     _pamDeferred: defer.Deferred | None
 
     def serviceStarted(self) -> None:
diff --git a/src/cowrie/ssh_proxy/server_transport.py b/src/cowrie/ssh_proxy/server_transport.py
index d4955df8..a980076a 100644
--- a/src/cowrie/ssh_proxy/server_transport.py
+++ b/src/cowrie/ssh_proxy/server_transport.py
@@ -306,9 +306,7 @@ class FrontendSSHTransport(transport.SSHServerTransport, TimeoutMixin):
         cencCS = ",".join([alg.decode("utf-8") for alg in encCS])
         cmacCS = ",".join([alg.decode("utf-8") for alg in macCS])
         ccompCS = ",".join([alg.decode("utf-8") for alg in compCS])
-        hasshAlgorithms = "{kex};{enc};{mac};{cmp}".format(
-            kex=ckexAlgs, enc=cencCS, mac=cmacCS, cmp=ccompCS
-        )
+        hasshAlgorithms = f"{ckexAlgs};{cencCS};{cmacCS};{ccompCS}"
         hassh = md5(hasshAlgorithms.encode("utf-8")).hexdigest()
 
         log.msg(
diff --git a/tox.ini b/tox.ini
index e5a61be7..3268f0d1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 skipsdist = True
-envlist = lint,docs,typing,py38,py39,py310,py311,pypy38,pypy39
+envlist = lint,docs,typing,py38,py39,py310,py311,pypy39
 deps = -r{toxinidir}/requirements.txt
 skip_missing_interpreters = True
 
@@ -10,7 +10,6 @@ python =
     3.9: py39
     3.10: py310, lint, docs, typing
     3.11: py311
-    pypy-3.8: pypy38
     pypy-3.9: pypy39
 
 [testenv]