# Lots of "No route to host" in Nginx error log **URL:** \ **Category:** NGINX\ **Created:** [January 6, 2010, 3:04am UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136 "2010-01-06T03:04:59Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [January 6, 2010, 3:04am UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/1 "2010-01-06T03:04:59Z")
Hi All, We got lots of “No route to host” in Nginx error log. ’ 2010/01/05 22:28:01 [error] 29366#0: \*26063920 connect() failed (113: No route to host) while connecting to upstream, client: 60.217.152.205, server: [test.com](http://test.com), request: GET /herundong/index.php HTTP/1.1, upstream: [http://x.y.z.a:80/herundong/index.php](http://x.y.z.a:80/herundong/index.php), host: [events.test.com](http://events.test.com) ’ Using curl on the Nginx proxy server like curl -v -H “Host: [events.test.com](http://events.test.com)” [http://x.y.z.a/herundong/index.php](http://x.y.z.a/herundong/index.php) works as expected. I searched in Nginx source code, and find even no ‘No route to host’ in its source code. Nginx version: 0.7.63 Backend are Apache servers. Current Nginx connections ~2k; Current Apache Connections ~800(counting all active and inactive connections) I saw on some connections of apache, there was a high Send-Q on established nginx-apache connections. Current Apache load average is under 1; Any suggestions? Thanks in advance. 2010-01-06 xufengnju ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [January 6, 2010, 3:36am UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/2 "2010-01-06T03:36:35Z")
xufengnju at 2010-1-6 10:04 wrote: > Hi All, > > We got lots of “No route to host” in Nginx error log. > ’ > 2010/01/05 22:28:01 [error] 29366#0: \*26063920 connect() failed (113: No route to host) while connecting to upstream, client: 60.217.152.205, server: [test.com](http://test.com), request: GET /herundong/index.php HTTP/1.1, upstream: [http://x.y.z.a:80/herundong/index.php](http://x.y.z.a:80/herundong/index.php), host: [events.test.com](http://events.test.com) > ’ > “No route to host” is the error string of system call connect. It’s > error value is 113. It means the server can’t find the route to > the backend server. This’s the network problem, not nginx. – Weibin Y. ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [January 7, 2010, 11:09am UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/3 "2010-01-07T11:09:04Z")
sometimes caused by upstreams’ firewall. 2010/1/6 Weibin Y. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [mailman.nginx.org archive](http://nginx.org/mailman/listinfo/nginx) – Ren Xiaolei ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [March 23, 2010, 1:27pm UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/4 "2010-03-23T13:27:51Z")
I find that error to , My Configuration is 4 upstreams, three upstreams is 1 cpu、2G memory,one is 2cpu、4Gmemory,the 2cpu’s doesn’t have this error,but the three 1cpus have this error,those server all in the same LAN ,anyone have the suggestion? Posted at Nginx Forum: > **[Re: Lots of "No route to host" in Nginx error log](https://forum.nginx.org/read.php?2,37426,66936#msg-66936)** > > Hi All, We got lots of "No route to host" in Nginx error log. ' 2010/01/05 22:28:01 \[error\] 29366#0: \*26063920 connect() failed (113: No route to host) while connecting to upstream, client: 60.217.152.205, server: test.com, request: GET... ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [March 23, 2010, 4:48pm UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/5 "2010-03-23T16:48:04Z")
On Tue, 2010-03-23 at 08:26 -0400, zhangyun112112 wrote: > I find that error to , My Configuration is 4 upstreams, three > upstreams is 1 cpu、2G memory,one is 2cpu、4Gmemory,the 2cpu’s doesn’t > have this error,but the three 1cpus have this error,those server all > in the same LAN ,anyone have the suggestion? As 崔玉松 said, this is a network issue, not a Nginx issue. You should check the proper function and configuration of both your LAN and the machines attached to it. Regards, Cliff ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [February 1, 2010, 9:41pm UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/6 "2010-02-01T21:41:07Z")
Hi, “No route to host” is not nginx error, if you use linux, please man route for detail information please make sure that the firewall does not block the port to your backend 2010/1/6 xufengnju [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [March 25, 2010, 12:22am UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/7 "2010-03-25T00:22:13Z")
Hi, We have that problem for awhile at our site. During the last two days, I investigated it and I pretty sure that it is cause by the netfilter firewall. Our backend servers are running RHEL5 and the 'iptables, rule that accept new connections from the proxy looks like: -A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp -s iii.jjj.kkk.lll --dport 9005 -j ACCEPT iii.jjj.kkk.lll is the IP address of the proxy server. And the last rule of the chain ‘RH-Firewall-1-INPUT’ is: -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited Yesterday I inserted a new rule in between in order to log incoming packets from the proxy that are going to be rejected. The rule looks like: -A RH-Firewall-1-INPUT -s iii.jjj.kkk.lll -j LOG The result was that for each ‘No route to host’ error logged in the error\_log file on the proxy server, there is a corresponding rejected packet logged on one of the backend servers. That means that our ‘iptables’ rules need a little bit of tuning. I thought of two solutions: 1. Remove the ‘state match’ test in the ACCEPT rule so the new rule looks like: -A RH-Firewall-1-INPUT -m tcp -p tcp -s iii.jjj.kkk.lll --dport 9005 -j ACCEPT 1. Add a new rule to ‘iptables’ which issues a REJECT with options ‘tcp-reset’ for the problematics packets. I hope that the proxy will reissue the request while receiving the RST flag from the backend. The rule should be inserted just before the last one and it should look like: -m tcp -p tcp -s iii.jjj.kkk.lll --dport 9005 -j REJECT --reject-with tcp-reset Tonight I will try the solution number 2. If the proxy react as I think it will, That will be a better solution than the number 1 which I will try eventually if the solution number 2 won’t work. Hope that this message will help you. Sorry for the poor english. Paul Posted at Nginx Forum: > **[Re: Lots of "No route to host" in Nginx error log](https://forum.nginx.org/read.php?2,37426,67536#msg-67536)** > > Hi All, We got lots of "No route to host" in Nginx error log. ' 2010/01/05 22:28:01 \[error\] 29366#0: \*26063920 connect() failed (113: No route to host) while connecting to upstream, client: 60.217.152.205, server: test.com, request: GET... ---
**Author:** ![xufengnju](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/e68b1a/32.png) [@xufengnju](https://www.ruby-forum.com/u/xufengnju)\ **Post date:** [March 25, 2010, 8:06pm UTC](https://www.ruby-forum.com/t/lots-of-no-route-to-host-in-nginx-error-log/181136/8 "2010-03-25T20:06:30Z")
## pacudes Wrote: > -p tcp -s iii.jjj.kkk.lll --dport 9005 -j ACCEPT > Yesterday I inserted a new rule in between in > tuning. > REJECT with options ‘tcp-reset’ for the > better solution than the number 1 which I will try > eventually if the solution number 2 won’t work. > > Hope that this message will help you. > > Sorry for the poor english. > > Paul Hi again, Finally the solution #2 solves the problem. I just made a last minute modification ( I restrict the rule to the -SYN packet) to the rule in ‘iptables’. The right rule looks like this: -A RH-Firewall-1-INPUT -m tcp -p tcp -s iii.jjj.kkk.lll --dport 9005 –syn -j REJECT --reject-with tcp-reset Don’t forget to adjust the source IP and destination port (-dport) according to your installation. Regards Paul Posted at Nginx Forum: [http://forum.nginx.org/read.php?2,37426,67798#msg-67798](http://forum.nginx.org/read.php?2,37426,67798#msg-67798)