DD-WRT Build Kills Postfix Rewrite - postfix-mta

Okay, this one is a head scratcher. Some background -- I have been running an old DD-WRT Kong build (8-June-2019) on my Netgear R7000 router for almost a year. I recently upgraded it to the latest BrainSlayer build and everything seemed fine, except for one thing. For over ten years, on a variety of routers, I have been using Postfix masquerade to rewrite the 'from' address on email that gets generated by scripts on my local domain on my MacBook Pro so that SMTP relay servers will see a legitimate email address. When I'm behind the new DD-WRT build, the emails are bounced back because the rewrite doesn't seem to occur and the SMTP relay is seeing a local domain address. I have since switched back to my old DD-WRT Kong build and Postfix masquerade is working again.
What could be going on with the new build that prevents Postfix rewrite from occurring? I am using the default firewall settings on both builds and all the other settings match. I'm baffled.

Okay, I'm a doofus -- I power-cycled my cable modem after trying the latest DD-WRT build again and this is now working. I usually don't do that after an upgrade, but now it will be the first thing that I do when I hit an issue. :-)
UPDATE -- never mind, the power-cycle fix is only temporary. I'm back on the old build.

Related

Wordpress not working after changing instance type on Google Cloud Platform

I changed my VM instance from "F1-micro" to "E2-micro". When I then restarted my machine, I couldn't access my webpage using the domain name, the webpage just shows an "Error 521" code - showing that my browser is working, CDN is working but the host has an erorr. When I paste the VMs IP address into my webpage, however, it show's the "Apache2 Debian Default Page".
Can somebody please help me with this?
The Error 521 message is caused by one of two situations:
First, check whether your WordPress site’s server is down. Even if everything else is configured properly, if your WordPress site’s server is offline, Cloudflare simply won’t be able to connect.
Second, your web server might be running fine but blocking Cloudflare’s requests. Because of how Cloudflare works, some server-side security solutions might inadvertently block Cloudflare’s IP addresses.
Cloudflare is a reverse proxy, all the traffic coming to your origin server will appear as if it’s coming from a small range of Cloudflare IPs (rather than each individual visitor’s unique IP address). Because of that, some security solutions will view high traffic from a limited number of IP addresses as an attack and block them.
Please check this link out in order to fix error 521 for Cloudflare and WordPress.
Turns out this problem was caused by my having installed the Debian Apache server package and it is causing collisions between it and the Apache shipped in the stack. Bitnami Stacks are completely self-contained and run independently of the rest of the software or libraries installed on your system.
So to fix this, all I had to do was run the following commands:
sudo systemctl stop apache2
sudo /opt/bitnami/ctlscript.sh restart

Configuring BIND for Ubuntu Web Server

I am looking for some assistance configuring BIND to host a DNS server on my web server.
I recently acquired a dedicated server running Ubuntu 14.04 LTS and I already have Nginx, PHP-FPM, MariaDB installed and working perfectly. My knowledge of postfix & dovecot are slim, so I followed this guide: A Mailserver on Ubuntu 14.04: Postfix, Dovecot, MySQL. The good news is that I've got mail coming in and going out as expected, but have come across another issue, which is some ISP and providers are denying the mail since there is no PTR records used.
So, I'm assuming I need to install and configure BIND to set up DNS and to set up a PTR record so that my mail will reach its destinations. I've tried Google with some tutorials but none of them seem clear for my purpose.
Installing a control panel, or one of those all-in-one scripts is out of the question since I already have the web server configured. Another issue is that some of them don't work with Nginx or use a different configuration of PHP. Plus, I want to learn how to do this on my own.
You don't have to install bind. Who ever has reverse DNS authority for your IP block will typically create a reverse name for you. Just request a reverse pointer record with the mail domain name for your IP.

IIS 7.5 running on Win7 Pro - access through a port other than 80 or 8080

I'm not sure I can adequately explain my dilemma, but here goes...
Our company has its own web server at xyz.com. I have a Win 7 Pro machine running a non-HTTP server program that communicates with an iPhone app used by our field crews. The path to this machine from outside the network is abc.xyz.com, and it's set for port 5000. The app, then, is programmed to exchange data (ASCII only) with the server at abc.xyz.com:5000. The server program is written in VB, and the system works very well like that.
What I would like to do now is to add IIS to this same machine and open it on port 5001, so I can run asp.net pages that will enhance the functionality of the app for our crews. The URL would be abc.xyz.com:5001, and they will access it through their phone browsers.
I have IIS 7.5 installed on the machine, and I have started it running with the "default web site," and I have the binding set for port 5001. So far I am able to access the IIS "Welcome" page only from the same machine. I can't get it to come up on any other machine either inside or outside the network.
In searching for clues for this problem, all I read indicates that it's pretty much a snap to get a web server running on your Windows 7 machine. But it hasn't been so much a snap for me. I've checked the sharing settings and the security settings, they seem to be ok, as best I can tell.
I am hoping that someone will help me identify some obscure setting somewhere that I am overlooking and get this going. But I also even wonder if this is something that can't be done, i.e. because there's another server program using the same path running on port 5000.
By the way, I am not the network administrator. I try to avoid getting him involved because he's difficult to work with. I am hoping that this is just between me and my server.
Thanks for any insight anyone can give me.
You mention that you can access the website from the machine itself on port 5001, but you can't access the site from another computer within the same network - this suggests to me that the Windows 7 built-in firewall is blocking the request - as it's a non-standard IIS port.
You should configure the firewall to allow incoming requests on port 5001. Open a command prompt (as administrator) and run the following:
netsh advfirewall firewall add rule name='IIS Website on Port 5001' dir=in protocol=TCP localport=5001 action=allow profile=any
I found the answer elsewhere on StackOverflow. I needed to add IUSR to the list of authorized users. So far I have tested it on my iPhone browser using 3G and it came through. Seems likely that it will work from anywhere, but I'm not yet ready to declare total success.

Trouble reaching client website from my computer with traceroute

I've been working on a client site for a few months now and I'm suddenly having a lot of trouble accessing it.
Chrome tells me:
This webpage is not available
Google Chrome's connection attempt to [client] was rejected. The website may be down, or your network may not be properly configured.
The website is available on any other computer, whether on the same wireless connection or not.
My traceroute shows a hop to localhost and then it stops. Interestingly enough, if I remove the "www" the site loads, and the traceroute without www works normally.
I've tried resetting my wireless adapter. I've tested this on multiple wireless networks and it just does not work on my computer.
I had this problem a few nights ago and it mysteriously worked for about a day and then the problem resumed this morning.
I do not have any proxy settings in Chrome. I've tried cycling the adapter, renewing the lease, and trying other routers. Just now, I also tried on ethernet and the problem persists. The problem also persists over users and browsers.
I don't notice any other sites affected. I am currently using a Mac. If I use Parallels to use Windows, it has no problem connecting to the site or tracing properly.
Does anyone have any troubleshooting suggestions?
Have you tried to flush the routing table on your machine?
/usr/bin/sudo /sbin/route flush

R httpd issue - help pages fail to load using local IP

This may be a general topic, but I came across the issue while working on some code using the Rook package.
The recent R versions include an http server. You may have seen this while checking for help topics using RGui. It opens a new browser with the IP/Port, etc.
For eg., if I enter ?paste, this brings up,
http://127.0.0.1:31234/library/.../paste.html
But if I use my IP, say 192.168.1.2 in place of 127.0.0.1, the page fails to load, I get an error
While trying to retrieve the URL:http://192....
The following error was encountered:
We can not connect to the server you have requested
I have other apps that have httpd interfaces, and I can go to those app's http interfaces using both 127.0.0.1 and 192.168.1.2 ... etc. So, as far as system/network permissions are concerned - I do not think that is the issue here.
Rather, there is something specific to the R httpd process that disallows it to be accessed using the domain name, etc ?
The above was tested in a corporate network. When I tried the same process from my home network it worked fine. However, since I already access http interfaces of many other locally installed apps from the corporate PC, I think there might be something specific to R's http process that needs to be checked ?
Workstation is running - Windows XP
Please let me know if you have any thoughts on the above,
Regards,
Raj.
Fixed it. The trick is to specify,
s <- Rhttpd$new()
s$start(listen="0.0.0.0",port="20000")
when starting the Rook process. Specifying 0.0.0.0 makes it listen to all the interfaces and now I can access it using my external IP. Thanks a lot for your help nonetheless !
When opening a TCP port, the local IP address may be chosen. For incoming connections, typically INADDR_ANY (-1) is supplied to bind(), which means to open the port on every available interface.
However, it is quite possible to open a port on just one interface on your machine (in this case, 127.0.0.1), simply by supplying the IP address of the interface. Seems that R does just this.
My guess is that you may have a proxy in place on your corporate network. Your browser is probably configured to use that proxy to access the Internet. Most browsers will exclude an address which they know to be local (127.0.0.1 or localhost) from using the proxy, but might not exclude any other IP.
Try disabling the proxy in your browser (even "Auto-Detect", completely turn the proxy off) and see if you're able to connect.
I had the same problem.
If you are using RStudio, this might be a bug in the RStudio. Check out this link:
https://support.rstudio.com/hc/communities/public/questions/202656007-Cryptic-error-on-starting-RStudio-daily-with-R-devel
Updating to the latest version of RStudio with the latest version of R fixes the problem.

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