Office tools:
"""Utility to reach a TCP server behind an SSH jump host.
This script establishes an SSH tunnel to a remote host and forwards a
local port to a TCP service that is only reachable from that host. Once
the tunnel is up, you can interact with the remote service using the
local forwarding port.
Example
-------
+python ssh_tunnel_client.py \
+ --ssh-host jump.example.com --ssh-user alice --ssh-key ~/.ssh/id_rsa \
+ --remote-host 10.0.0.5 --remote-port 5012
+
+The script will open localhost:5012 by default; any TCP client pointed to
+that address/port pair will effectively communicate with 10.0.0.5:5012
+through the SSH tunnel.
+"""
+from __future__ import annotations
+
+import argparse
+import getpass
+import logging
+import socketserver
+import sys
+from typing import Optional, Tuple
+
+import paramiko
+
+
+LOGGER = logging.getLogger(__name__)
+
+
+class ForwardServer(socketserver.ThreadingTCPServer):
+ daemon_threads = True
+ allow_reuse_address = True
+
+
+class TunnelHandler(socketserver.BaseRequestHandler):
+ """Forwards a local TCP connection through the SSH transport."""
+
+ def handle(self) -> None: # noqa: D401 - see class docstring.
+ transport: paramiko.Transport = self.server.transport # type: ignore[attr-defined]
+ remote_host: str = self.server.remote_host # type: ignore[attr-defined]
+ remote_port: int = self.server.remote_port # type: ignore[attr-defined]
+
+ try:
+ chan = transport.open_channel(
+ "direct-tcpip",
+ (remote_host, remote_port),
+ self.request.getsockname(),
+ )
+ except Exception as exc: # pragma: no cover - network specific
+ LOGGER.error("Failed to open SSH channel: %s", exc)
+ return
+
+ if chan is None:
+ LOGGER.error("SSH channel creation returned None")
+ return
+
+ LOGGER.info(
+ "Forwarding connection from %s to %s:%s",
+ self.client_address,
+ remote_host,
+ remote_port,
+ )
+
+ try:
+ while True:
+ rdata = self.request.recv(1024)
+ if len(rdata) == 0:
+ break
+ chan.sendall(rdata)
+
+ response = chan.recv(1024)
+ if len(response) == 0:
+ break
+ self.request.sendall(response)
+ finally:
+ chan.close()
+ self.request.close()
+
+
+def parse_args(argv: Optional[list[str]] = None) -> argparse.Namespace:
+ parser = argparse.ArgumentParser(description=__doc__)
+ parser.add_argument("--ssh-host", required=True, help="SSH jump host")
+ parser.add_argument("--ssh-port", type=int, default=22, help="SSH port")
+ parser.add_argument("--ssh-user", required=True, help="SSH username")
+ parser.add_argument(
+ "--ssh-key",
+ help="Path to private key for authentication (optional if password is provided)",
+ )
+ parser.add_argument(
+ "--ssh-password",
+ help="Password for SSH authentication (optional if key is provided)",
+ )
+ parser.add_argument(
+ "--remote-host",
+ required=True,
+ help="Destination host reachable from the SSH server",
+ )
+ parser.add_argument(
+ "--remote-port",
+ type=int,
+ default=5012,
+ help="Destination TCP port on the remote host",
+ )
+ parser.add_argument(
+ "--local-port",
+ type=int,
+ default=5012,
+ help="Local port for the forwarded connection",
+ )
+ parser.add_argument(
+ "--verbose",
+ action="store_true",
+ help="Enable debug logging",
+ )
+ return parser.parse_args(argv)
+
+
+def create_ssh_client(args: argparse.Namespace) -> paramiko.SSHClient:
+ client = paramiko.SSHClient()
+ client.load_system_host_keys()
+ client.set_missing_host_key_policy(paramiko.WarningPolicy())
+ password = args.ssh_password
+ if password is None and args.ssh_key is None:
+ password = getpass.getpass("SSH password: ")
+
+ client.connect(
+ args.ssh_host,
+ port=args.ssh_port,
+ username=args.ssh_user,
+ key_filename=args.ssh_key,
+ password=password,
+ look_for_keys=args.ssh_key is None and password is None,
+ )
+ return client
+
+
+def start_forwarding(
+ client: paramiko.SSHClient,
+ remote_host: str,
+ remote_port: int,
+ local_port: int,
+) -> Tuple[ForwardServer, Tuple[str, int]]:
+ transport = client.get_transport()
+ if transport is None or not transport.is_active():
+ raise RuntimeError("SSH transport is not available")
+
+ server = ForwardServer(("127.0.0.1", local_port), TunnelHandler)
+ server.transport = transport # type: ignore[attr-defined]
+ server.remote_host = remote_host # type: ignore[attr-defined]
+ server.remote_port = remote_port # type: ignore[attr-defined]
+ return server, server.server_address
+
+
+def main(argv: Optional[list[str]] = None) -> int:
+ args = parse_args(argv)
+
+ logging.basicConfig(
+ level=logging.DEBUG if args.verbose else logging.INFO,
+ format="%(asctime)s %(levelname)s %(name)s: %(message)s",
+ )
+
+ try:
+ client = create_ssh_client(args)
+ except paramiko.AuthenticationException as exc:
+ LOGGER.error("Authentication failed: %s", exc)
+ return 1
+ except paramiko.SSHException as exc:
+ LOGGER.error("Unable to establish SSH connection: %s", exc)
+ return 1
+
+ LOGGER.info(
+ "Connected to %s. Forwarding localhost:%d to %s:%d",
+ args.ssh_host,
+ args.local_port,
+ args.remote_host,
+ args.remote_port,
+ )
+
+ try:
+ server, local_address = start_forwarding(
+ client,
+ args.remote_host,
+ args.remote_port,
+ args.local_port,
+ )
+ except Exception as exc:
+ LOGGER.error("Failed to start port forwarding: %s", exc)
+ client.close()
+ return 1
+
+ LOGGER.info("Tunnel established on %s:%d", *local_address)
+
+ try:
+ server.serve_forever()
+ except KeyboardInterrupt:
+ LOGGER.info("Interrupted by user, shutting down")
+ finally:
+ server.server_close()
+ client.close()
+
+ return 0
+
+
+if __name__ == "__main__":
+ sys.exit(main())
I get these errors from distccd (in detach mode) everytime distcc client wants to distribute some jobs to do:
From distcc source code:
Here is a Python script that scans directories for duplicate files by comparing file sizes and MD5 hashes:
Key features:
1. Uses two-pass comparison for efficiency:
- First groups files by size
- Then compares MD5 hashes of same-size files
2. Handles large files using chunked reading
3. Skips inaccessible files gracefully
4. Provides clear command-line output
5. Uses MD5 hashing for content comparison
To use:
1. Save as `find_duplicates.py`
2. Run with: `python find_duplicates.py /path/to/directory`
The script will:
1. Scan all subdirectories recursively
2. Identify files with identical content
3. Group duplicates together in the output
4. Show full paths of duplicate files
Note: MD5 is used for speed, but you could modify the script to use SHA-256 for cryptographic-strength hashing by replacing `hashlib.md5()` with `hashlib.sha256()`.
This C++ code has bits access routines to get and set some bits:
dataBits.h:
I bought a USB/XLR Dynamic Microphone "Maono HD-300T" from Amazon a few months ago and was disappointed with its low or quiet sound made by my Windows 11 when connected through its USB connection. I tested the microphone through its XLR connection to my Yamaha Audio mixer, no phantom power is needed (as this is a dynamic microphone), but I had to set the preamp gain all the way to its max to get a decent volume.
The volume setting was set to 100%, but I had no luck making it better. I was thinking perhaps it required a special USB driver, but nope, it simply used the stock Windows driver (Maono's official website doesn't mention anything about a special driver for this particular model).
At one point I gave up on using it for my video conferences and meetings and back to just using the built-in microphone on my webcam (Logitech HD 920). Last week I found an idea to test the microphone using my PC analog microphone input. I found and bought an XLR-to-3.5mm TRS which is perfect to connect the microphone to my PC. The good thing with built-in audio from motherboard is that Windows support boost gain to +30 dB, so I was able to make the microphone work properly.
Not being satisfied with that one solution, I googled around and found somebody mentioned about Equalizer APO and its accompanying UI interface, Peace Equalizer APO. Got them installed and ran, I then connected my Microphone to one of my PC's USB. After playing around on how to use it (It's a lot of parameter controls and kind of confusing, at least for beginners), I managed to boost the gain of the microphone to + 3- dB. Hooray!
Below is my settings (I saved it as "My Microphone mono" settings. It is based on the "Microphone mono" preset configuration.):
Set the preamp to gain around +20 dB. As can be seen, I turn on "Prevent Clipping" down below, so even if set it to the max (+30 dB gain), we shouldn't get the audio clipped. The downside to crank it up to the max is we'd also get louder noise.
I was having issues again with the unexpected slowness of my internet access. This time turns out due to failure in ethernet auto-negotiation. My PC's ethernet interface is 2.5 Gbps, as well MoCA adapter that is connected to it. It was working fine, until yesterday, where I got only 90's Mbps on SpeedTest.
There is cool PowerShell command to display the link speed: Get-NetAdapter.
We can create a DOS shell wrapper, so invoking this from a regular DOS prompt would work.
For example, I put this command in a file called "getnet.ps1". I created another DOS script called "getnet.cmd" with the content of it just calling getps1.ps1:
In getnet.ps1:
Get-NetAdapter
In getnet.cmd:
call getnet.ps1
For example:
C:\Users\anon\bin>type getnet.cmd
call getnet.ps1
C:\Users\lshih\bin>getnet
C:\Users\lshih\bin>call getnet.ps1
Name InterfaceDescription ifIndex Status MacAddress LinkSpeed
---- -------------------- ------- ------ ---------- ---------
Bluetooth Network Conn... Bluetooth Device (Personal Area Netw... 27 Disconnected 38-FC-98-13-E9-2A 3 Mbps
2.5 GigE LAN Realtek Gaming 2.5GbE Family Contr...#2 21 Up 04-42-1A-0C-2C-C4 2.5 Gbps
vEthernet (2.5 GigE LAN) Hyper-V Virtual Ethernet Adapter 16 Up 00-15-5D-76-F1-69 10 Gbps
vEthernet (1 GigE LAN) Hyper-V Virtual Ethernet Adapter #3 52 Up 00-15-5D-D2-5B-EB 10 Gbps
1 GigE LAN Intel(R) I211 Gigabit Network Conn...#2 14 Up 04-42-1A-0C-2C-C3 1 Gbps
vEthernet (VirtualBox ... Hyper-V Virtual Ethernet Adapter #2 40 Up 00-15-5D-F1-53-24 10 Gbps
VirtualBox Host-Only N... VirtualBox Host-Only Ethernet Adapter 7 Up 0A-00-27-00-00-07 1 Gbps
vEthernet (WSL) Hyper-V Virtual Ethernet Adapter #4 75 Up 00-15-5D-9C-4E-D0 10 Gbps
My gateway router has a cool security feature called Intrusive Threat Prevention (ITS). When I checked the statistics from where most of the attacks occurred to my gateway, majority the attacks come from China.
I have been wondering so far how much power a 5G phone, like iPhone 12, can transmit to RAN (Radio Access Network), a.k.a. a base station.
According to the table in standard document ETSI TS 138 101-1, section 6.2.1 for "UE maximum output power", the maximum power for class 2 is 26 dBm (0.398 Watt) and for class 3 is 23 dBm (0.199 Watt). Class 2 UE (User Element) only transmits at certain frequency bands only, namely n41, n77, n78, and n79, while class 3 transmits in all spectrums.
To understand what are those NR bands, see 5G NR frequency bands - Wikipedia
Supposedly the server we want to access is at address 192.168.1.11 and it only supports older key hash algorithms. Add those algorithms in ~/.ssh/config, such as:
Host 192.168.1.11
KexAlgorithms +diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa
MACS hmac-md5,hmac-sha1
exifprobe
exiftags
exiftran
exiv2
fim
mediainfo (my favorite)
To install some of those, just install the following:
forensics-all
forensics-extra
I recently bought a 5 TB USB3 hard disk to back up my data (mostly my photo and video files. I had a data disaster recently, so I bought the EaseUS disaster backup data recovery tool, but it required a huge amount of data to restore).
Out of the box, without paying attention to the factory default format it has (extFAT), the 5 TB space has only about 0.6 TB space left. I doubt I had that much-used data (as the source of the recovered data is from a 1 TB hard drive). After doing some investigation (the detail is down below), I found out that the allocation unit size (AUS) of the removable hard disk is pretty big, I think it is too big to storage average files. So I am in the process of backing up the data to my other hard drive (NTFS, 4k AUS), before I can reformat the drive to have a smaller AUS.
Meanwhile, I am not decided whether to stick with extFAT or change it to NTFS. I don't really care about portability to other OSes, especially Apple products (sorry MacOS!), as I am pretty much a Windows (plus Linux) user. Yes, I am all aware that so far Linux supports R/W to NTFS in userspace only (the kernel driver only supports read and some limited write access, but that requires some enabling). But, the good news is that, according to the recent news, a company called Paragon is willing to make its full-blown proprietary NTFS driver (which fully supports NTFS features) to the Linux community. The effort is planned to be available starting in Kernel 5.15. This will really boost the performance and features of NTFS in Linux.[1]
To have 256K AUS seems too expensive. According to [3] for Test 3 and 4 (Read & Write, 1 GB of data file), extFAT is slightly faster, but for smaller files (Test 1 and 2, 1 GB file size), NTFS prevails. For duplication or deletion (Test 8 and 9), NTFS is more than 1.60 faster than FAT32 and 1.3 faster than extFAT).
Some useful information:
For 2 TB to 16 TB hard drive, 4 KB AUS is enough for an NTFS-formatted hard drive.[2]
Disk Partition Information:
C:\Windows\System32>diskpart
Ref:
[1] Linux boosts Microsoft NTFS support as Linus Torvalds complains about GitHub merges | ZDNet
[2] Default cluster size for NTFS, FAT, and exFAT (microsoft.com)
[3] Flexense - Data Management Software - FAT32 vs. exFAT vs. NTFS USB3 Performance Comparison
I recently upgraded my Internet connection plan with Xfinity from Internet 200 Mbps plus TV to 900 Mbps Superfast plan (with TV plan dropped. Who cares with TV these days?). It was a good deal plan, as I now pay less with a lot faster nominal Internet speed.
In the beginning, after waiting an hour as told by the customer service, I saw the upstream speed improved to 20+ Mbps, but the upstream speed did not increase (stayed at around 140 Mbps). A few calls/chats with the customer service representatives (they sent a few update signals) and modem and router reboots nothing improved.
After the last call to them, they decided to send a technician to visit the next day. I had tried almost everything (except setting the router's settings to factory defaults). My home network setup is little bit complicated, with the AP router and DOCSIS 3.1 modem sitting in a mounted rack in the walking closet.
The coaxial cable from ISP is split through a 1-to-8 Moca-Ready splitter (5-2300 MHz, -11 dB drop between Out and In), because I need to connect the TV in the living room through MoCA as well as some bedrooms and home office. In the beginning, I thought the chocking was due to interference with MoCA (as the DOCSIS cable modem shared the same coax medium with MoCA modems). Not sure whether I still need to change that splitter (-11 dB drop is a little too much, not counting the bandwidth is only up to 2300, not 2400 or 2500 MHz. But when I checked the MoCA specs, the frequency span for MoCA 2.5 is from 1002 to 1675 MHz.)
Out of my patience (I use the Internet on a daily basis as part of Work From Home with Citrix connection, hence requires constant and speedy internet link), I decided to simplify the connection by removing the set-top box (which soon I'd return as I'd no longer have TV service), so the cable modem was wired directly to the ISP (not through splitter). This did not resolve the data rate, although it improved the SNR in the modem.
Out of my frustration, I factory reset my Synology Router Rt2600a and redid the speed test. And...voila! I got 700+ Mbps. Yes, it's still far from 900 Mbps as promised, but at least it's 4x faster than what I got before. Turned out, the "Threat Prevention" add-on feature in Synology Router was the culprit. It was CPU-intensive processing, which shouldn't be performed by a normal CPU, probably by a special or dedicated CPU doing this kind of inspection and prevention.
I still really need to have an intrusion prevention feature as it has been securing my home network heavily from hackers and spam. Perhaps it is time to shop for a dedicated intrusion prevention device.
System: Dell Precision WorkStation T3500 (all builds)
Motherboard: Dell 09KPNV
Memory: 5.6 GB free of 12 GB (6x2GB) @ 1.3 GHz DIMM DDR3-1333 (PC3-10600)
Display: 1920 x 1080 - 32 Bit colors, 1680 x 1050 - 32 Bit colors,
OS: Windows 10
BIOS Date: 20130528
CPU: Intel Xeon W3550 (QC, 8 threads @3.06 GHz)
Disk: Seagate Barracuda 7200.12 1TB
VGA: Dual NVidia Quadro NVS 420
Here is the list parts upgrades.
DO NOT mix E or U modules (E modules tend to run faster).
T3500 doesn't support registered modules (R modules!), and there is 6 Slots on the motherboard.
Max speed: 1333 MHz (PC10600)
Memory PN’s:
Recommended Memory configurations:
With Upgraded 700W EVG 700B Power Supply:
The motherboard doesn't support NVME protocol, so we cannot boot O/S from it that requires UEFI, which you're not going to find on any eight year old PC system. But NVME SSD can be used to store data after booting (e.g, just to store video game data).
NVME.2 SSD Adapter *Required to Install NVME.2*
Recommended NVME.2 SSDs:
- Heatsink compound Arctic Silver
M.2 is a form factor:
NVME SSD vs SATA SSD:
SATA III Hard Drive SATA III SSD NVMe SSD
exportICAROOT=/opt/Citrix/ICAClientCopy files in/usr/share/ca-certificates/mozilla/* to $ICAROOT/keystore/cacertsRehash the certificate by the following command: $ICAROOT/util/ctx_rehash
My Logitech USB Speakarphone has stopped working since I did something wrong (which I don't remember). Various troubleshooting and zillions of searches on the Internet did not fix the issue, until today.
The issue was the device did not make any sound at all. Checking via ALSA and Kernel log said everything was fine as shown below:
$ lsusb
...
Bus 002 Device 011: ID 046d:0a06 Logitech, Inc.
Bus 002 Device 009: ID 046d:c51c Logitech, Inc.
$ inxi -A
Audio: Device-1: Intel 82801I HD Audio driver: snd_hda_intel
Device-2: ViXS Systems XCode 2100 Series driver: N/A
Device-3: AMD Cape Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series] driver: snd_hda_intel
Device-4: Logitech type: USB driver: snd-usb-audio
Sound Server: ALSA v: k4.15.0-135-generic
In Linux, there is very powerful tool to rename files based on pattern we specify. The pattern follows Perl-like regular expression.
For example, if I have files as follow:
and I want to rename them by replacing the "_-_" part to be just "-". The single command to do that is:
(the argument "-n" above is to tell rename not to actually perform renaming, but just to display what it would do). I use "/g" in the regular expression to tell it to rename all occurrences of "_-_" throughout the file name, not just for the first time it encounters it.
The following bash script utilizes mediainfo command line to retrieve various metadata inside an MP3 (or any media file, in fact):
#!/bin/sh i=0 for f in "$@" do i=$((i+1)) printf "%d," $i mediainfo --Inform="General;%CompleteName%,%Format%,%OverallBitRate_Mode%,%BitRate%,%FileSize/String4%" "${f}" done
For example (I put the above into a script named 'bitrate.sh'):
I recently had access issue to my Plex server (running on Linux). It was fine sometime ago, but lately everytime I tried to access it from my LG TV or my phone, they said the server was offline. I'd followed various instructions and troubleshooting I found on the Internet with no luck. Here is the list of steps I did:
Turned out it was due to IPv6 connection was enabled on the Plex server! Once I disabled it, now I could watch my movies or stream my music to other devices. My LG TV apparently did not support IPv6 yet.
The content of $HOME/.indent.pro:
-as
-lp
-bad
-bap
-bbb
-bbo
-bli0
-nbc -c33 -cd33 -ncdb -nce -ci4 -cli0
-c4
-ncdw
-cp33 -cs -d0 -di1 -nfc1 -nfca -hnl -i8 -ip0 -l75 -lp -npcs
-nprs -npsl -saf -sai -saw -nsc -nsob -nss
-v