# dhcpcd-5.2.8 sets MTU = 576

## e3k

it started with my kvpnc being able to connect. i was able to ping pcs but not able to ssh them.

then i noticed this error:

Jan  5 15:09:29 localhost vpnc[9962]: esp sendto: Message too long

so i checked with ifconfig the mtu of eth0 and it was 576.

until now i fixed this with using dhclient where i get MTU = 1500 by editing:

```
/etc/conf.d/net

modules=( "dhclient" )

config_eth0=( "dhclient" )

```

my question is if this is a dhcpcd bug. or does the ISP send me the small MTU number??

---

ok i did find now on my wifes pc same issue on arch linux.

did fix it now by commenting out this:

# Respect the network MTU.

#option interface_mtu

in /etc/dhcpcd.conf

now it seems that it is the ISP.

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## g.e.n.t.u.x.

hello e3k.

if that issue occurs at your router than the isp is the one. if you dhcp to a router then prepare your dhcpd.conf.

greetz gentux

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## e3k

except that i have no router but a switch.

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## Jaglover

 *e3k wrote:*   

> except that i have no router but a switch.

 

Your ISP is giving you public IP addresses? What type of connection is this, PPTP?

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## e3k

yes they give me a dynamic and public ip.

i dont get it with PPTP, its a connection to a cisco vpn...

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## g.e.n.t.u.x.

and how u establish your ppp connection?

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## e3k

its not ppp its regular cable internet.

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## Jaglover

Not clear. ISP gives you one public address for every computer? (BTW, some ISP's use PPTP)

Define regular cable internet please? I have cable internet with cable modem for instance, is that what you have? Since I've given only one public address I have to use a NAT router.

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## e3k

yes we have 2 different ip addresses for each PC (checked on both pcs via http://www.whatismyip.com/). you have to register your MAC though at the ISP to be able to use the internet.

i have no idea what it is. its not optic. there is a coaxial cable attached to the modem and on the other side is normal LAN cable. i put this one into a switch and further to the 2 PCs.

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## g.e.n.t.u.x.

maybe over television cable?

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## e3k

exactly thats it. kind of dumb from me   :Embarassed: 

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## g.e.n.t.u.x.

just/like me in other things  :Wink: .

then u have a direct connection. And you should contact your isp for this question. because for example the german telekom set up the MTU to 1496 cause of for bytes for the dsl-header. if i set this up to 1500 then no connection can be established.

maybe your connection is fast enough for this mtu or it is misseted what can occure sometimes.

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## e3k

did already. lets wait a few days or weeks maybe somebody will answer  :Wink: 

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## UberLord

 *e3k wrote:*   

> now it seems that it is the ISP.

 

Correct it is the ISPs issue.

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## e3k

until now the ISP just thinks its my router (which i do not have) lets see what will be in the next mail.

---

well now they told me thats a default setting and they do not plan to change it. so much for upc chello slovakia...

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