Arch Linux

neverEnough

Member

Registered: 2017-04-15

Posts: 2

[SOLVED] MTU issue: Configuring an arch router, https gone

Hi all, first post and new arch user,
i'm quite unused to all the news introduced by arch compared to pre-systemd debian, glad to learn
I'm setting up a DIY router with archlinux. Everything went fine (thx to the awesome archwiki) until i noticed my laptop can't reach any https site when connected to it.
The debian laptop works perfectly with the old debian router (so this station is absolutely out of the question), but when i switch to the new wifi on new router then i can ping, visit http sites but https will keep loading forever.
Before i noticed the issue was related to https i tried to play with everything i was aware of - dnsmasq settings, comparing surf results with smartphone (pretty the same), getting crazy with systemd-networkd, routing, ipv6 where i'm not expert at all (if i did it correctly it should be disabled atm). But now i'm really surrended.
Ssl/tls thing is over my ability. I really can't understand what is involved into this issue. A protocol related limitation looks pretty ugly to me when you are setting routes and masquerade.

I'm really lost, thx for any advice

Last edited by neverEnough (2017-04-15 14:11:17)

x33a

Forum Fellow

Registered: 2009-08-15

Posts: 4,587

Re: [SOLVED] MTU issue: Configuring an arch router, https gone

Please post all the relevant configuration files, firewall rules and routing table. Also, pinging https sites makes no sense, since it doesn't work at the same layer.

neverEnough

Member

Registered: 2017-04-15

Posts: 2

Re: [SOLVED] MTU issue: Configuring an arch router, https gone

Found! MTU was the issue!

On the old working router:

# ip a
[..]
8: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1456 qdisc pfifo_fast state UNKNOWN group default qlen 3
    link/ppp 
    inet ###.###.###.### peer 192.###.###.###/32 scope global ppp0
       valid_lft forever preferred_lft forever

On the faulty new router:

# ip a
[..]
15: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc fq_codel state UNKNOWN group default qlen 3
    link/ppp 
    inet ###.###.###.### peer 192.###.###.###/32 scope global ppp0
       valid_lft forever preferred_lft forever

Solution
https://wiki.archlinux.org/index.php/pp … o_not_work

Sorry but i couldn't find that before without the MTU keyword.

Also, pinging https sites makes no sense

Neither pinging http does. RFC 792 (and probably newest)

x33a

Forum Fellow

Registered: 2009-08-15

Posts: 4,587

Re: [SOLVED] MTU issue: Configuring an arch router, https gone

Also, pinging https sites makes no sense

Neither pinging http does. RFC 792 (and probably newest)

HTTP was implied in my reply. In any case, glad you got it sorted.