Network – Create a WiFi access point that shares the Ethernet connection

I'm using Ubuntu Server 18.04 on a Raspberry Pi 3. The idea of ​​what I want to achieve is illustrated by the following scheme:

                             Raspberry Pi
             WiFi        ┌──────bridge──────┐     Ethernet
   Laptop <~.~.~.~.~.~.~>│ (wlan0)br0(eth0) │<---------------->Device
                                    /                           /
   192.168.1.200             192.168.1.1               192.168.1.10

Basically, the sensors collect data on the device and the Raspberry runs a MERN app that displays them and can be accessed by anyone connected to the WiFi access point.

I've accomplished this configuration in the Raspbian operating system after this post, but I need to do something equivalent on Ubuntu Server 18.04 because I need the latest version of MongoDB for the device to store the data.

wifi-ap (Details here) works efficiently to create the access point, but the Ethernet connection to the device is not bridged. I tried to give and static IP in the netplan and confuse with that dhcp but it still did not work.

Is there a way to make the bridge with that? wifi-ap? What do I miss?
Or is there a way to replicate this in Ubuntu Server 18.04? Or another way to make it work?

Thank you in advance.

Gigabit Ethernet – TPE-224WS can not work at full speed with Edgerouter X.

I have a TPE-224WS that has four (presumably) Gigabit compatible ports. I also have an Edgerouter X, which also supports Gigabit.

If I link them together, both with Autonegotiation enabled, they start at 100M (in my experience normal for the Edgerouter), but never negotiate for the full 1000M.

If I either tell the Edgerouter to force full speed with ethtool, or instruct the TPE-224WS to force the port to 1000M or both at the same time, the devices will not be connected at all.

What could cause such a problem?

EDIT: I tried to update the firmware to the latest available version.

Networking – Does a Point-to-Point Ethernet Connection Need a Crossover Cable?

I have heard mixed answers to this question. I think historically the answer is yes, but modern Ethernet controllers are supposed to support device detection by enumerating the twisted pairs in the cable to determine their alignment.

However, I do not know the answer for sure. So for a connection like this:

laptop <---> laptop

In contrast to

laptop <---> switch <---> laptop

Does a special crossover Ethernet cable need to be used?

usb – A device that enables wireless to Ethernet communication

I do not know if such a device exists or not necessarily the right terminology.
I have a wireless device that only has WiFi as the communication mode.
I want to use a device that is Wi-Fi and USB capable, so when connected to a PC, it's a USB RNDIS device. If such a device allows a wireless connection to the hardware, this would be helpful.

Does such a device exist?

What I have now is a Raspberry Pi Zero W that acts as such, but I think Pi has so many other things that could be reduced, like HDMI, camera, GPIO, etc.

macos – Is Ethernet Status a password theft?

Recently I bought Ethernet status and activated the full version for an additional charge of € 2.29 and activated all functions. I still have the confirmation email.

Today I noticed that the "full version" apparently was no longer active:

No full version anymore?

So I click on "Check Full Version Features", no big deal, and should be able to re-enable. Just click "Restore Purchase," right?

Restore purchase

And then it hits me …

Enter my password

This is not a native Apple user interface, right? How can I be sure that not only does the app try to trick me into entering my AppStore password? Who should say that my entered credentials are not sent to the manufacturer (or anyone else)?

I entered a wrong (!) Password while keeping WireShark over my shoulder. I hoped I could see something lazy. But I could not find any proof of that; No direct connection to Apple and no direct connection to another location. A lot of IPs, lots of traffic (trying to close as many applications as possible) and most, if not all, encrypted with SSL. Actually, there's nothing interesting to see and the amount of data is a bit too overwhelming for me to make sense of it.

Can someone confirm or refute my suspicions? Any advice (except that I do not enter my current password in this interface)? I may even have entered my AppStore password during initial installation and immediate update. Thank goodness I also use 2FA and have recently changed my password to be on the safe side. Now I have an app that I suddenly do not trust anymore (which may be unfair!) And I'm not sure if I should continue …

Network – The connection of the Realtek RTL8111 / 8168/8411 Ethernet card is accidentally disconnected

System information:

  • Kernel: latest OPENVZ kernel (2.6.32-042stab140.4)
  • Centos release: CentOS Release 6.10 (final)
  • Network Card Type:
    Ethernet Controller: Realtek Semiconductor Co., Ltd. RTL8111 / 8168/8411 PCI Express Gigabit Ethernet Controller (Version 06)

Problem:
We have a strange problem with our server. The network is randomly separated from time to time. Sometimes it runs for a few days and then the connection to the network is disconnected, sometimes the connection is disconnected daily and sometimes it has been in operation for 2 weeks so it is totally unreliable. There are no errors in messages.log or dmesg.log or other logs. We only see that the server is not connected to the network. With a KVM I was able to log in and restart the network card with the commands "ifdown eth0 && ifup eth0". Then the network is online again.

What we have tried:

  • Install and update the kernel
  • The current kernel uses the r8169 driver, and we know that some people solved their network problems by installing the r8168 driver. We did that, the problem still exists.

Network configuration:

DEVICE=eth0
ONBOOT=yes
HWADDR=D4:3D:7E:****
BOOTPROTO=static
IPADDR=144.76.****
NETMASK=255.255.255.255
SCOPE="peer 144.76.****"
IPV6INIT=yes
IPV6ADDR=2a01:4f8:200:****
IPV6_DEFAULTGW=fe80::1
IPV6_DEFAULTDEV=eth0
ADDRESS0=0.0.0.0
NETMASK0=0.0.0.0
GATEWAY0=144.76.219.1

/etc/resolv.conf and / etc / sysconfig / network are also set up correctly

Commands and their output that you may need to help me:

Settings for eth0:
        Supported ports: ( TP MII )
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Advertised pause frame use: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                             100baseT/Half 100baseT/Full
                                             1000baseT/Full
        Link partner advertised pause frame use: Symmetric
        Link partner advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: pumbg
        Wake-on: g
        Current message level: 0x00000033 (51)
                               drv probe ifdown ifup
        Link detected: yes
eth0      Link encap:Ethernet  HWaddr D4:3D:7E:EC:F1:64
          inet addr:144.76.219.8  Bcast:144.76.219.8  Mask:255.255.255.255
          inet6 addr: 2a01:4f8:200:9207::2/64 Scope:Global
          inet6 addr: fe80::d63d:7eff:feec:f164/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:216416 errors:0 dropped:0 overruns:0 frame:0
          TX packets:236235 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:25416051 (24.2 MiB)  TX bytes:112658399 (107.4 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:41671 errors:0 dropped:0 overruns:0 frame:0
          TX packets:41671 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:7606777 (7.2 MiB)  TX bytes:7606777 (7.2 MiB)

venet0    Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet6 addr: fe80::1/128 Scope:Link
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:217176 errors:0 dropped:0 overruns:0 frame:0
          TX packets:194950 errors:0 dropped:1 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:105725409 (100.8 MiB)  TX bytes:20479815 (19.5 MiB)
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether d4:3d:7e:ec:f1:64 brd ff:ff:ff:ff:ff:ff
    inet 144.76.219.8 peer 144.76.219.1/32 brd 144.76.219.8 scope global eth0
    inet6 2a01:4f8:200:9207::2/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::d63d:7eff:feec:f164/64 scope link
       valid_lft forever preferred_lft forever
3: venet0:  mtu 1500 qdisc noqueue state UNKNOWN
    link/void
    inet6 fe80::1/128 scope link
       valid_lft forever preferred_lft forever
Module                  Size  Used by
vzethdev                8245  0
pio_kaio               14060  0
pio_nfs                19043  0
pio_direct             30148  2
pfmt_raw                3333  0
pfmt_ploop1             6703  2
ploop                 120433  11 pio_kaio,pio_nfs,pio_direct,pfmt_raw,pfmt_ploop1
simfs                   5189  0
vzrst                 206937  0
nf_nat                 23122  1 vzrst
nf_conntrack_ipv4       9650  2 nf_nat
nf_defrag_ipv4          1523  1 nf_conntrack_ipv4
vzcpt                 156425  1 vzrst
nfs                   449026  3 pio_nfs,vzrst,vzcpt
lockd                  78281  2 vzrst,nfs
fscache                61345  1 nfs
auth_rpcgss            46116  1 nfs
nfs_acl                 2655  1 nfs
sunrpc                274118  6 pio_nfs,nfs,lockd,auth_rpcgss,nfs_acl
nf_conntrack           81593  4 vzrst,nf_nat,nf_conntrack_ipv4,vzcpt
vziolimit               3775  0
vzdquota               55467  0 (permanent)
ip6t_REJECT             4447  0
ip6table_mangle         3629  0
ip6table_filter         3025  0
ip6_tables             19020  2 ip6table_mangle,ip6table_filter
xt_length               1330  0
xt_hl                   1539  0
xt_tcpmss               1615  0
xt_TCPMSS               3549  0
iptable_mangle          3453  0
iptable_filter          2897  2
xt_multiport            2772  2
xt_limit                2126  0
xt_dscp                 2065  0
ipt_REJECT              2423  19
ip_tables              18183  2 iptable_mangle,iptable_filter
vzevent                 2171  1
vznetdev               18984  4
vzmon                  25679  5 vzrst,vzcpt,vznetdev
vzdev                   2725  5 vzethdev,vziolimit,vzdquota,vznetdev,vzmon
ipv6                  342460  90 vzrst,vzcpt,ip6t_REJECT,ip6table_mangle
ext3                  240851  1
jbd                    80628  1 ext3
freq_table              4944  0
mperf                   1565  0
intel_pstate           14660  0
ppdev                   8321  0
parport_pc             22658  0
parport                37265  2 ppdev,parport_pc
iTCO_wdt                7342  0
iTCO_vendor_support     3064  1 iTCO_wdt
r8169                  76421  0
mii                     5544  1 r8169
i2c_i801               13273  0
i2c_core               29164  1 i2c_i801
sg                     29542  0
lpc_ich                13579  0
mfd_core                1935  1 lpc_ich
shpchp                 29554  0
ext4                  431830  3
jbd2                   93732  1 ext4
mbcache                 8201  2 ext3,ext4
raid1                  33193  3
sd_mod                 37126  8
crc_t10dif              1217  1 sd_mod
ahci                   43194  6
xhci_hcd              181527  0
video                  21990  0
output                  2417  1 video
wmi                     6287  0
dm_mirror              14904  0
dm_region_hash         12189  1 dm_mirror
dm_log                  9938  2 dm_mirror,dm_region_hash
dm_mod                102855  2 dm_mirror,dm_log
00:00.0 Host bridge: Intel Corporation 4th Gen Core Processor DRAM Controller (rev 06)
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, fast devsel, latency 0
        Capabilities: (e0) Vendor Specific Information: Len=0c 
        Kernel driver in use: hsw_uncore

00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06) (prog-if 00 (VGA controller))
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, fast devsel, latency 0, IRQ 11
        Memory at f7800000 (64-bit, non-prefetchable) (size=4M)
        Memory at e0000000 (64-bit, prefetchable) (size=256M)
        I/O ports at f000 (size=64)
        Expansion ROM at  (disabled)
        Capabilities: (90) MSI: Enable- Count=1/1 Maskable- 64bit-
        Capabilities: (d0) Power Management version 2
        Capabilities: (a4) PCI Advanced Features
        Kernel modules: i915

00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05) (prog-if 30 (XHCI))
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, medium devsel, latency 0, IRQ 31
        Memory at f7c00000 (64-bit, non-prefetchable) (size=64K)
        Capabilities: (70) Power Management version 2
        Capabilities: (80) MSI: Enable+ Count=1/8 Maskable- 64bit+
        Kernel driver in use: xhci_hcd
        Kernel modules: xhci-hcd

00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04)
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, fast devsel, latency 0, IRQ 11
        Memory at f7c16000 (64-bit, non-prefetchable) (size=16)
        Capabilities: (50) Power Management version 3
        Capabilities: (8c) MSI: Enable- Count=1/1 Maskable- 64bit+

00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05) (prog-if 20 (EHCI))
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, medium devsel, latency 0, IRQ 16
        Memory at f7c14000 (32-bit, non-prefetchable) (size=1K)
        Capabilities: (50) Power Management version 2
        Capabilities: (58) Debug port: BAR=1 offset=00a0
        Capabilities: (98) PCI Advanced Features
        Kernel driver in use: ehci_hcd

00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5) (prog-if 00 (Normal decode))
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
        I/O behind bridge: 00002000-00002fff
        Memory behind bridge: df200000-df3fffff
        Prefetchable memory behind bridge: 00000000df400000-00000000df5fffff
        Capabilities: (40) Express Root Port (Slot+), MSI 00
        Capabilities: (80) MSI: Enable- Count=1/1 Maskable- 64bit-
        Capabilities: (90) Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Capabilities: (a0) Power Management version 3
        Kernel modules: shpchp

00:1c.1 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #2 (rev d5) (prog-if 00 (Normal decode))
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
        I/O behind bridge: 0000e000-0000efff
        Prefetchable memory behind bridge: 00000000f0000000-00000000f00fffff
        Capabilities: (40) Express Root Port (Slot+), MSI 00
        Capabilities: (80) MSI: Enable- Count=1/1 Maskable- 64bit-
        Capabilities: (90) Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Capabilities: (a0) Power Management version 3
        Kernel modules: shpchp

00:1c.3 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d5) (prog-if 01 (Subtractive decode))
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=03, subordinate=04, sec-latency=0
        Capabilities: (40) Express Root Port (Slot+), MSI 00
        Capabilities: (80) MSI: Enable- Count=1/1 Maskable- 64bit-
        Capabilities: (90) Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Capabilities: (a0) Power Management version 3

00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05) (prog-if 20 (EHCI))
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, medium devsel, latency 0, IRQ 23
        Memory at f7c13000 (32-bit, non-prefetchable) (size=1K)
        Capabilities: (50) Power Management version 2
        Capabilities: (58) Debug port: BAR=1 offset=00a0
        Capabilities: (98) PCI Advanced Features
        Kernel driver in use: ehci_hcd

00:1f.0 ISA bridge: Intel Corporation H87 Express LPC Controller (rev 05)
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, medium devsel, latency 0
        Capabilities: (e0) Vendor Specific Information: Len=0c 
        Kernel driver in use: lpc_ich
        Kernel modules: lpc_ich

00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 (AHCI mode) (rev 05) (prog-if 01 (AHCI 1.0))
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 32
        I/O ports at f0b0 (size=8)
        I/O ports at f0a0 (size=4)
        I/O ports at f090 (size=8)
        I/O ports at f080 (size=4)
        I/O ports at f060 (size=32)
        Memory at f7c12000 (32-bit, non-prefetchable) (size=2K)
        Capabilities: (80) MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: (70) Power Management version 3
        Capabilities: (a8) SATA HBA v1.0
        Kernel driver in use: ahci
        Kernel modules: ahci

00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05)
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: medium devsel, IRQ 18
        Memory at f7c11000 (64-bit, non-prefetchable) (size=256)
        I/O ports at f040 (size=32)
        Kernel modules: i2c-i801

02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
        Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Flags: bus master, fast devsel, latency 0, IRQ 33
        I/O ports at e000 (size=256)
        Memory at f0004000 (64-bit, prefetchable) (size=4K)
        Memory at f0000000 (64-bit, prefetchable) (size=16K)
        Capabilities: (40) Power Management version 3
        Capabilities: (50) MSI: Enable+ Count=1/1 Maskable- 64bit+
        Capabilities: (70) Express Endpoint, MSI 01
        Capabilities: (b0) MSI-X: Enable- Count=4 Masked-
        Capabilities: (d0) Vital Product Data
        Capabilities: (100) Advanced Error Reporting
        Capabilities: (140) Virtual Channel
        Capabilities: (160) Device Serial Number 01-00-00-00-68-4c-e0-00
        Kernel driver in use: r8169
        Kernel modules: r8169

03:00.0 PCI bridge: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI Bridge (rev 03) (prog-if 00 (Normal decode))
        Flags: bus master, fast devsel, latency 0
        Bus: primary=03, secondary=04, subordinate=04, sec-latency=32
        Capabilities: (50) MSI: Enable- Count=1/1 Maskable- 64bit+
        Capabilities: (78) Power Management version 3
        Capabilities: (80) Express PCI/PCI-X Bridge, MSI 00
        Capabilities: (c0) Subsystem: Micro-Star International Co., Ltd. (MSI) Device 7816
        Capabilities: (100) Virtual Channel
        Kernel modules: shpchp

Even if the network was down "cat / sys / class / net / eth0 / carrier" returned "1" and cat / sys / class / net / eth0 / operstate returned "up" so that the network card was connected. ..

So, what's up ? I read in many forums that this card could have problems and buggy. What do you suggest? Am I right that this problem is definitely a hardware problem or a driver error? I think the solution would be to get a newly connected network card and disable this onboard card. What do you think, thank you in advance for any help!

Network – Can not connect to the Internet when both Ethernet and Wi-Fi are connected in Ubuntu 16.04

I have Ubuntu 16.04 (Machine 1) and Windows 10 (Machine2). I connected the Ubuntu to the WiFi with IP 192.168.0.110 and I can just surf the internet.

I have to get away C++ Development on Ubuntu from Windows with Visual Studio. I have connected the ethernet cable between Ubuntu and Windows. On both sides I have set the static IP, d. H. Ubuntu has 192.168.0.150 and windows has 192.168.0.149, I can ping Windows from Ubuntu and vice versa. But when I try to surf the Internet on Ubuntu, it does not work. If I disconnect the cable connection to Ubuntu, I can easily surf the Internet. I do not know what I did wrong here, so I can not connect to the internet on Ubuntu.

Can someone please suggest an idea to me. Thank you very much

Network – Share an Internet connection from a Windows 10 computer to a Linux computer over Ethernet

I'm trying to share an internet connection from a Windows 10 computer to a Linux computer (Lubuntu) via Ethernet.

I have the following setup:
(Linux machine) —- Ethernet —- (Windows 10 machine) —- WLAN —- (Router Modem Internet)

My Windows computer sees the Internet, but my Linux computer does not. Pretty sure the two machines can talk to each other.

I'm rummaging around in the dark and do not know what to try next. So far I have tried the following:

On Windows machine:
Network Connections displays both my wifi and my LAN (which it calls "unidentified network")
– I clicked on the network properties and selected "Allow other users to connect to the Internet through these computers" (I have tried this on both the Wifi network and the LAN).
– I tried to bridge the network connections
– When I perform a Windows Network Diagnostic on the LAN, I get the message "LAN connection does not have valid IP configuration

Under Linux:
– When I touch google.com, I get the message "Temporary name resolution error".
– I start ipconfig on the Windows machine to find the IP address in the LAN. Then I try to ping that from the linux machine, and that seems to work.

Linux – host unreachable if eth0 does not have IPv4 in the ethernet bridge

I am currently trying to configure an Ethernet bridging VPN using OpenVPN. However, when I try to set up the Ethernet bridge, the server (Raspberry Pi) loses the connection to the internal network. I use the following script to initialize my ethernet bridge

#!/bin/bash
# Define physical ethernet interface to be bridged
# with TAP interface(s) above.
eth="eth0"
eth_ip="192.168.144.200"
eth_netmask="255.255.255.0"
eth_broadcast="192.168.144.255"
eth_gateway="192.168.144.1"
eth_mac="B8:27:EB:48:6D:E3"


# Define Bridge Interface
br="br0"

# Define list of TAP interfaces to be bridged together
tap="tap0"

#################################
# Set up Ethernet bridge on Linux
# Requires: bridge-utils
#################################

for t in $tap; do
    openvpn --mktun --dev $t
done

brctl addbr $br
brctl addif $br $eth

for t in $tap; do
    brctl addif $br $t
done

for t in $tap; do
    ifconfig $t 0.0.0.0 promisc up
    iptables -A INPUT -i $t -j ACCEPT
done

iptables -A INPUT -i $br -j ACCEPT
iptables -A FORWARD -i $br -j ACCEPT

ifconfig $eth 0.0.0.0 promisc up
ifconfig $br $eth_ip netmask $eth_netmask broadcast $eth_broadcast
ip link set $br address $eth_mac
dhclient $br
ifconfig $br promisc up
route add default gw 192.168.144.1

After debugging the entire story, I found out that

ifconfig $eth 0.0.0.0 promisc up

leads to my connection problem. Any ideas on how to solve this problem? Normally, only the bridge interface should have an IP address. But if I do not assign eht0 an IP address, the terminal connection is broken off and I can no longer connect.

Note: I have already checked iptables and net.ipv4.ip_forward is set to 1,