I am trying to set up a fallback connection on a Linux machine that has access to two different routers on different subnets on running on the same network.  I have been reading several other posts related to this but am struggling to get it to work.  The setup is as follows:      Internet 1                 Internet 2           ^                          ^           |                          | --------------------     ------------------------ [Router 1: 10.1.1.1]     [Router 2: 192.168.2.10] --------------------     ------------------------           ^                          ^           |                          |            \                        /            --------------------------            [eth0              eth0:1]            [10.1.1.14   192.168.2.50]            [     linux machine      ]            --------------------------  In this example, eth0 is configured with DHCP, and eth0:1 is configured as a static IP.   I want to connect via the internet on the router at 192.168.2.10, but fall back to the router at 10.1.1.1 if 192.168.2.10 is unreachable.  According to some other posts I was reading, it seemed setting route metrics on the default routes should do the trick.  I ran the following on the linux machine and tested by unplugging the router at 192.168.2.10 to ensure that it would fallback to 10.1.1.1: ip route add default via 192.168.2.50 dev eth0 metric 100 ip route add default via 10.1.1.1 dev eth0 metric 200  Running a route -n showed: Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         192.168.2.10    0.0.0.0         UG    100    0        0 eth0 0.0.0.0         10.1.1.1        0.0.0.0         UG    200    0        0 eth0 10.1.1.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0 192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0  But a simple ping to Google DNS failed.  Removing the 192.168.2.10 route allows it to work just fine. What am I missing, or am I interpreting the route metric wrong?  Is there a better way to do this? I have seen other cases where the routes are added to different tables, and then ip rules are setup for certain IPs to use different connections, but I want all connections to try to go out Router 2 but to go out Router 1 if Router 2 is down. Thanks!
I have two internet connection from two different ISP. ADSL on eth0 and 4G on wlan0. Is there any way that if one ISP fails, the other take over automatically without a physical router and by Host OS (Ubuntu 18.04)?
I use time manager for a polygon layers with dates and it works. I would like to see the cummulative addition of my polygons. So I have 4 periods I want the poylgons from 1900-1950 to be added to the new ones in 1950-2000 etc in the next time step. How can I perform that or does another open source tool exist for that? Any questions relating to status updates, or asking if anything is going to be patched for these vulnerabilities should be closed as duplicates of this question.    are in the news right now and sound pretty severe. I don't see any security updates from Ubuntu that cover these vulnerabilities.  What is Ubuntu doing about these vulnerabilities, and what should Ubuntu users be doing?  These are CVE-2017-5753, CVE-2017-5715 and CVE-2017-5754. When I open the game, the screen stays at the Mojang sign and then crashes. It has something to do with my texture pack, but I can't start the game to change it and it won't let me delete the texture pack folder alone.  I've already deleted the bin and resources folders in the minecraft folder and downloaded the game again. I opened it but the same problem was still there.  How do I properly perform a clean uninstall of the game? I want to select questions that are only tagged as SQL, SQLServer, SQLSever 2008. I am not interested in questions that have anything more than these tags. How do i select such questions only ? 2D random walk within a bounded area Lost credit card replaced with new card and new numbers. Credit score affected? I recently left my credit card at a bar so I reported it as lost to my bank, and my bank said I will get a replacement within a few days. For what it's worth, I picked my card up from the bar a few days later and made sure to cut it up.  The new credit card has arrived and has new numbers. Will this negatively affect my credit score?  VISA, Chase Bank, USA. What are these tags related to on the Newest Questions page? On the right, there is a widget that lists "Related Tags" (left − SO April 2013, right − MSE May 2014):         What are they related to? There isn't even a question selected. Are they related to the whole displayed list?  This can be seen on every SE site. I get this error: dpkg: unrecoverable fatal error, aborting: files list file for package `fonts-tlwg-kinnari' contains empty filename What's the difference between centre of mass & centre of gravity for massive bodies? My book says:     For most of the small objects, both are same. But for mammoth ones, they are really different ones. And in a gravity-less environment, COG is absent; COM still exists.   Ok, what's the big deal when things are small and big? How these two :  &amp; ? Covering map between orientable compact connected surfaces without boundary with genus $g$ Similar to a previous question I asked, this is the other question that I couldn't answer in an exam I gave for my Topology course:  Suppose $g_1,g_2$ are non-negative integers such that $2-2g_2$ divideds $2-2g_1$. I have to construct a covering map $S_{g_1} \rightarrow S_{g_2}$, where $S_g$ is denotes an orientable compact connected surface without boundary with genus $g$.  Now, I attempted to try this problem for surfaces with smaller genera, for example a 2-torus and a 2-sphere. Clearly $2-2g$ is the Euler Characteristic of the said surface, and by classification of surfaces we have to only consider connected sum of 2-tori. So, I have $\chi(S^2)=2$, and $\chi(T^2) = 0$, here we have $2$ dividing $0$, hence I have to construct a covering map from $T^2 \rightarrow S^2$, and I have no idea how to move forward.  Addendum: I have to got great answers to my question here but I had a doubt when it comes to the points being mapped, specifically in Giulio Bresciani's answer. Clearly the handles of the figure is mapped to the handles in the figure above, but I'm unable to understand the mapping of the twist of the cover (above figure) to the extreme handles of the base (the figure below). Any help? find exclude directory How to connect to Android through SSH over 3G/4G public IP? this is my first question on PhysicsSE (I'm already an user of MathSE).   I'm a mathematics students trying to understand Faraday's law, that is   $$\varepsilon= -\frac{d \Phi_B}{dt}$$  where $\varepsilon$ means electromotive force and   $$\Phi_B=\iint \mathbf{B}\cdot d\mathbf{S}$$   means flux of magnetic field. As my textbook points out, there is an interpretation problem here: if the change in magnetic flux is due to movement of the conductor, then free charges in it are subject to Lorentz force, which then causes a current. On the contrary, if the conductor holds steady in a changing magnetic field, the induced current must be explained in terms of an electric field $\mathbf{E}$, described by the equations   $$\begin{cases} \nabla \cdot \mathbf{E}=\frac{\rho}{\varepsilon_0} \\ \nabla \times \mathbf{E} = - \frac{\partial \mathbf{B}}{\partial t}\end{cases}.$$  Question Do those equations hold if we have a moving conductor in a stationary magnetic field? I guess not: this would mean $\mathbf{E}=\mathbf{0}$. How to solve this? I'm at Reachwater Rock and I've encountered a series of doors, the first I had to open using the Emerald Claw I found near a body, but now the door's telling me to use an Ivory Claw. Where can I find it, because I don't have it in my inventory yet. Fix a wobbly Shimano freehub? Frequency of the sound when blowing in a bottle Prologue:  This is an effort to follow up on  which is marked as a duplicate of  highly voted and status-declined feature request (although they seem to be different, one focusing on the OP and the other on the downvoter).   My New Year's resolution was to downvote more.  So on January 3rd or so, I saw a post that was low quality, and downvoted.  Two days later, I came back to see if it was ready to be deleted or had gotten piled with downvotes, to find it with a significant positive score!  At which point, I noticed that the answer had been significantly improved.  So I retracted my downvote, changed it to an upvote, and immediately resumed my dearth of downvoting again.  I think I have a responsibility to downvote bad posts, despite that oh-so-painful -1 rep penalty.  But if I am also going to have the responsibility to follow up on every downvote I cast, I'm not going to bother. I don't want my downvote to leave a residual penalty on posts that were once low quality, and I am not going to trouble myself to keep checking up on every post I downvoted.  Can a downvoter have an option to be notified when a post they voted down was edited?  I wouldn't make this an automatic thing, because not all downvoters want it, and it isn't applicable to all cases of downvoting (although  that this should be part of the responsibility of a downvoter).  Personally, I would make this a universal toggle on-off option on the user profile page, not a question-by-question option, but I don't have strong feelings about it. Show that if $f(z)$ is an entire function such that it takes real values on the lines $Im(z)=0$ and $Im(z)=a$ (for some $a \in \mathbb{R}_{\neq 0})$, then $f$ is periodic with period $2 i a$.    So here is my thought process: First of all by reflection principle $f(\bar{z})=\overline{f(z)}$ so if our function $f$ is given in the strip $0 \leq Im(z) \leq a$, then its values on $-a \leq Im(z) \leq a$ follow by reflection principle. Then by imposing $f(z)=f(z+2 ia)$ we can intuitively see that this will define an entire function by looking at how the strips $na \leq Im(z) \leq 2na$ seamlessly stack on top of each other. Is this logical? And how would one prove this analytically? Difference between a gerund acting as subject and an infinitive acting as a subject? I am wondering whether there is any difference between a gerund acting as subject and an infinitive acting as a subject. I inherited a project using SQL Server 2005.  Recently there were some performance problems and I started looking at the indexes, and found  _dta_index_survey_25_135059617__K1_K10_K19:     id ASC, sent_date ASC, group_id ASC   and  _dta_index_survey_21_364632442__K18_K1_K2_K9:     group_id ASC, id ASC, campaign_id ASC, sent_date ASC   which appears to be generated by some kind of automatic performance tuning tool.  I think SQL Server comes with something like that but I'm not familiar with it.  Anyway, id is the primary key, and what I'm trying to understand here is how it could possibly be beneficial to include the primary key within a secondary index... because you have to have the leftmost pieces of information to use an index and if you know id then you've got the row anyway.  Can someone explain why a tool would have generated these indexes and if there's any point in keeping them?  Just because the indexes are getting used doesn't mean they're a good design.  SQL Server is using the wrong indexes lately, and I'm trying to determine why. More specifically, queries against this table that ran in milliseconds a month ago are now taking multiple seconds.  The table is huge (4M rows), and growing steadily, but at the same pace it's been going at for years.  Almost every query joins across group_id or campaign_id.  Often both.  The application almost never specifically selects or sorts by the PK, but I could see how ID could be useful when comparing or merging lists of IDs within the database engine.  ... But id is also an identity column, and an index holds lists of row ids, so it still seems redundant to have the ID in the key when it's also in the index "buckets".  And the additional fields could still be covered by the index without being part of the key.  I discovered that (id, sent_date, group_id) hardly ever gets read.  Meanwhile (group_id, id, campaign_id, sent_date) is one of the hottest indexes.  Next I found that an index which I thought was pretty reasonable (campaign_id, sent_date, group_id, id) also has a index_columns_include of every other column in the table, and occupies more space than the primary clustered index on id!  (but it's also pretty hot...)  Surely I can replace it with a simple (campaign_id, sent_date, group_id)?