2

Try adding a -t nat so you select the NAT table, or maybe -t mangle. Pretty sure it will default to looking at the filter table, which won't have a PREROUTING chain. You need to specify which table you are looking at. sh# iptables -C PREROUTING -t nat -p udp -m udp --dport 5060 -j CT --helper sip


2

The feature you are looking for is available only since kernel 5.8, as described in this UL SE Q/A: How to set sysctl using kernel command line parameter?: sysctl.*= [KNL] Set a sysctl parameter, right before loading the init process, as if the value was written to the respective /proc/sys/... file. Both '.' and '/' are recognized as ...


2

I am one of the core developers of OpenConnect and maintainers of the vpnc-script — which is used by both vpnc and OpenConnect for routing and DNS configuration. This error message actually comes from the vpnc-script, not from vpnc itself, and… This error doesn't matter at all. It come from the command ip -4 route flush cache, which triggers IPv4 route ...


2

No. Only the local process listening on port 2222 will receive the packet. If it replies, the reverse translation will take place, and outgoing reply packet will be out from port 22. Fourth rule will make any encountered packets destined to port 22 to be re-routed to your local port 2222, even if they weren't meant to be for this machine. Since you don't ...


1

With nmap you can scan range in a sub-net with this syntax (i.e to scan 192.168.0.1 to 192.168.1.30 only) : nmap 192.168.0.1-30 So you should easily be able to adapt it with your command : nmap -v -sn -n 192.168.1.55-65 -oG - | awk '/Status: Down/{print $2}'


1

You can only reserve two types of external IP Addresses. Global & Regional, IPv4 supports both but IPv6 only supports Global. You cannot reserve IPv6 addresses for VM Instances since it only supports Global IP and can only be used for global load balancers as stated on the documentation. To know more about Regional and global IP addresses check this link....


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Here's the history of the changes related to this issue: 2018-10-12 09:47:39 -0700 net: Evict neighbor entries on carrier down is committed on netdev -next tree: this is responsible of removing neighbor entries when a link gets a carrier down, with a rationale in the commit message. 2018-10-22 07:47:45 +0100 kernel v4.19 is released. This still doesn't ...


1

VirtualBox by default uses MAC based filtering straight in the virtual switch code. It knows the MAC address of the VM, and doesn't deliver any other packets (besides multicast and broadcast). The reason is of course security - otherwise a VM can try to redirect traffic etc etc. After several hours, I rebooted all hosts and traffic started going through the ...


1

From answer for How to disable Internet connection for a single process and Block network access of a process Then, starting a process without network access is as simple as: unshare -n program ... This creates an empty network namespace for the process. That is, it is run with no network interfaces, including no loopback. In below example we add -r to run ...


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