How can I make sure ping traffic over ipsec is going outside?

I’ve got a VPN tunnel (ipsec / StrongSwan) setup, connected. The other side is apparently able to ping me through the tunnel. However a ping from my side is said to be never received on the other side. The other side (that I cannot control) is thus assuming it’s a configuration issue from my side.

I’m really not sure about this, because I can see the ping packets going out when tcpdumping:

$   ping -c 5 PING ( 56(84) bytes of data. --- ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4009ms  (at the same time in another console) $   tcpdump host REMOTE 09:22:07.539582 IP LOCAL > REMOTE: ESP(spi=0xXXXXXX,seq=0x3), length 132 09:22:08.547608 IP LOCAL > REMOTE: ESP(spi=0xXXXXXX,seq=0x4), length 132 (... one packet per ping ...) 

The ESP traffic is obviously my ping. To make sure I’ve disabled all firewalling from my side.

Thus my question: How can I make sure the ping packets are going out and received? What can be the cause and what can I do more to help debug the issue?

As a side note, I’ve got another VPN setup and working, using the exact same configuration.

player.stopVideo, player.playVideo, etc. not working outside of event functions calls with youtube-api

I am trying to create a button that allows the user to click it and stop the embedded youtube video. However, whenever I try and call the player object itself to use the function player.playVideo() I get an error saying the function is not defined.

Player is globally defined and set when the Youtube API loads (just like the tutorial on their website). Function calls to playVideo work just fine when events trigger their usage, but using it outside of those simply do not work.

'''javascript // 2. This code loads the IFrame Player API code asynchronously. var tag = document.createElement('script');  tag.src = ""; var firstScriptTag = document.getElementsByTagName('script')[0]; firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);  // 3. This function creates an <iframe> (and YouTube player) //    after the API code downloads. var player; function onYouTubeIframeAPIReady() {     isReady=true;     player = new YT.Player('player', {         height: '390',         width: '640',         videoId: 'M7lc1UVf-VE',         events: {             'onReady': onPlayerReady,             'onStateChange': onPlayerStateChange         }     }); }  // 4. The API will call this function when the video player is ready. function onPlayerReady(event) {     playVideo(); }  // 5. The API calls this function when the player's state changes. //    The function indicates that when playing a video (state=1), //    the player should play for six seconds and then stop. var done = false; function onPlayerStateChange(event) {     if ( == YT.PlayerState.PLAYING && !done) {         setTimeout(stopVideo, 6000);         done = true;     } } function stopVideo() {     player.pauseVideo(); }  function playVideo() {     player.playVideo(); }  //The function that is run when the button is pressed, only in this case                        // stopVideo not work! function togglePlay() {     if(isPlaying) {         stopVideo();     } else {         playVideo();     } } ''' 

Expected: Youtube video plays Actual: Error player.playVideo is not a function

Cute/striking application(s) of Snake Lemma outside homological algebra

I already asked this question on MSE here, but still received no answer. I hope I will be more lucky here.

When you teach algebra to students, it’s often easy to find cute/direct applications of “big” theorems to motivate how useful these results can be.

For example, group actions, Sylow theorems, or the first isomorphism theorems have nice applications and can provide non trivial results in few lines.

However, I’m struggling to find such applications concerning the Snake Lemma outside homological algebra, so an answer like “we can use it to prove the $ n$ -lemma” (pick for $ n$ your favorite integer), is not the kind of answer I’m looking for.

Precisely, I would like to know applications of the Snake Lemma, even direct and/or not very sophisticated, but which would have been difficult or lengthy to prove without it.

I found such an example here, which is rather sophisticated:

Maybe you will have other examples , even shorter or simpler?

Thanks for your help !

Any way to stop the “outside of your domain” notifications across Google Apps?

I use a GSuite account as my primary Google account for everything and across calendar / hangouts / etc, I see a “outside of your domain” notification for a lot of random things. Sometimes it’s just a message – other times, I have to specifically allow someone from outside my domain to act.

Is there any global setting to allow it always across all apps?

How long does the Archfey warlock’s Fey Presence feature last when used outside of combat?

A Warlock who chooses the Archfey patron gets the Fey Presence feature at level 1 (PHB, p. 109). The PHB says this ability, when used, lasts “until the end of your next turn”:

Starting at 1st level, your patron bestows upon you the ability to project the beguiling and fearsome presence of the fey. As an action, you can cause each creature in a 10-foot cube originating from you to make a Wisdom saving throw against your warlock spell save DC. The creatures that fail their saving throws are all charmed or frightened by you (your choice) until the end of your next turn.

Once you use this feature, you can’t use it again until you finish a short or long rest.

When a character uses the power out of combat, how should this be handled by a DM? How long does it last? Should “your next turn” be interpreted as the player’s turn?